1.
Right ascension
–
Right ascension is the angular distance measured eastward along the celestial equator from the vernal equinox to the hour circle of the point in question. When combined with declination, these astronomical coordinates specify the direction of a point on the sphere in the equatorial coordinate system. Right ascension is the equivalent of terrestrial longitude. Both right ascension and longitude measure an angle from a direction on an equator. Right ascension is measured continuously in a circle from that equinox towards the east. Any units of measure could have been chosen for right ascension, but it is customarily measured in hours, minutes. Astronomers have chosen this unit to measure right ascension because they measure a stars location by timing its passage through the highest point in the sky as the Earth rotates. The highest point in the sky, called meridian, is the projection of a line onto the celestial sphere. A full circle, measured in units, contains 24 × 60 × 60 = 86 400s, or 24 × 60 = 1 440m. Because right ascensions are measured in hours, they can be used to time the positions of objects in the sky. For example, if a star with RA = 01h 30m 00s is on the meridian, sidereal hour angle, used in celestial navigation, is similar to right ascension, but increases westward rather than eastward. Usually measured in degrees, it is the complement of right ascension with respect to 24h and it is important not to confuse sidereal hour angle with the astronomical concept of hour angle, which measures angular distance of an object westward from the local meridian. The Earths axis rotates slowly westward about the poles of the ecliptic and this effect, known as precession, causes the coordinates of stationary celestial objects to change continuously, if rather slowly. Therefore, equatorial coordinates are inherently relative to the year of their observation, coordinates from different epochs must be mathematically rotated to match each other, or to match a standard epoch. The right ascension of Polaris is increasing quickly, the North Ecliptic Pole in Draco and the South Ecliptic Pole in Dorado are always at right ascension 18h and 6h respectively. The currently used standard epoch is J2000.0, which is January 1,2000 at 12,00 TT, the prefix J indicates that it is a Julian epoch. Prior to J2000.0, astronomers used the successive Besselian Epochs B1875.0, B1900.0, the concept of right ascension has been known at least as far back as Hipparchus who measured stars in equatorial coordinates in the 2nd century BC. But Hipparchus and his successors made their star catalogs in ecliptic coordinates, the easiest way to do that is to use an equatorial mount, which allows the telescope to be aligned with one of its two pivots parallel to the Earths axis
Right ascension
–
Right ascension (blue) and
declination (green) as seen from outside the
celestial sphere.
2.
Declination
–
In astronomy, declination is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declinations angle is measured north or south of the celestial equator, the root of the word declination means a bending away or a bending down. It comes from the root as the words incline and recline. Declination in astronomy is comparable to geographic latitude, projected onto the celestial sphere, points north of the celestial equator have positive declinations, while those south have negative declinations. Any units of measure can be used for declination, but it is customarily measured in the degrees, minutes. Declinations with magnitudes greater than 90° do not occur, because the poles are the northernmost and southernmost points of the celestial sphere, the Earths axis rotates slowly westward about the poles of the ecliptic, completing one circuit in about 26,000 years. This effect, known as precession, causes the coordinates of stationary celestial objects to change continuously, therefore, equatorial coordinates are inherently relative to the year of their observation, and astronomers specify them with reference to a particular year, known as an epoch. Coordinates from different epochs must be rotated to match each other. The currently used standard epoch is J2000.0, which is January 1,2000 at 12,00 TT, the prefix J indicates that it is a Julian epoch. Prior to J2000.0, astronomers used the successive Besselian Epochs B1875.0, B1900.0, the declinations of Solar System objects change very rapidly compared to those of stars, due to orbital motion and close proximity. This similarly occurs in the Southern Hemisphere for objects with less than −90° − φ. An extreme example is the star which has a declination near to +90°. Circumpolar stars never dip below the horizon, conversely, there are other stars that never rise above the horizon, as seen from any given point on the Earths surface. Generally, if a star whose declination is δ is circumpolar for some observer, then a star whose declination is −δ never rises above the horizon, as seen by the same observer. Likewise, if a star is circumpolar for an observer at latitude φ, neglecting atmospheric refraction, declination is always 0° at east and west points of the horizon. At the north point, it is 90° − |φ|, and at the south point, from the poles, declination is uniform around the entire horizon, approximately 0°. Non-circumpolar stars are visible only during certain days or seasons of the year, the Suns declination varies with the seasons. As seen from arctic or antarctic latitudes, the Sun is circumpolar near the summer solstice, leading to the phenomenon of it being above the horizon at midnight
Declination
–
Right ascension (blue) and declination (green) as seen from outside the
celestial sphere.
3.
88 modern constellations by area
–
The table below ranks the 88 modern constellations by the solid angle that they subtend in the sky, measured in square degrees and millisteradians. Before Delportes work, there was no standard list of the boundaries of each constellation and this skew will increase over the years and centuries to come. However, this does not change the angle of any constellation
88 modern constellations by area
–
Hydra is the largest constellation.
4.
Constellation
–
A constellation is formally defined as a region of the celestial sphere, with boundaries laid down by the International Astronomical Union. The constellation areas mostly had their origins in Western-traditional patterns of stars from which the constellations take their names, in 1922, the International Astronomical Union officially recognized the 88 modern constellations, which cover the entire sky. They began as the 48 classical Greek constellations laid down by Ptolemy in the Almagest, Constellations in the far southern sky are late 16th- and mid 18th-century constructions. 12 of the 88 constellations compose the zodiac signs, though the positions of the constellations only loosely match the dates assigned to them in astrology. The term constellation can refer to the stars within the boundaries of that constellation. Notable groupings of stars that do not form a constellation are called asterisms, when astronomers say something is “in” a given constellation they mean it is within those official boundaries. Any given point in a coordinate system can unambiguously be assigned to a single constellation. Many astronomical naming systems give the constellation in which an object is found along with a designation in order to convey a rough idea in which part of the sky it is located. For example, the Flamsteed designation for bright stars consists of a number, the word constellation seems to come from the Late Latin term cōnstellātiō, which can be translated as set of stars, and came into use in English during the 14th century. It also denotes 88 named groups of stars in the shape of stellar-patterns, the Ancient Greek word for constellation was ἄστρον. Colloquial usage does not draw a distinction between constellation in the sense of an asterism and constellation in the sense of an area surrounding an asterism. The modern system of constellations used in astronomy employs the latter concept, the term circumpolar constellation is used for any constellation that, from a particular latitude on Earth, never sets below the horizon. From the North Pole or South Pole, all constellations south or north of the equator are circumpolar constellations. In the equatorial or temperate latitudes, the term equatorial constellation has sometimes been used for constellations that lie to the opposite the circumpolar constellations. They generally include all constellations that intersect the celestial equator or part of the zodiac, usually the only thing the stars in a constellation have in common is that they appear near each other in the sky when viewed from the Earth. In galactic space, the stars of a constellation usually lie at a variety of distances, since stars also travel on their own orbits through the Milky Way, the star patterns of the constellations change slowly over time. After tens to hundreds of thousands of years, their familiar outlines will become unrecognisable, the terms chosen for the constellation themselves, together with the appearance of a constellation, may reveal where and when its constellation makers lived. The earliest direct evidence for the constellations comes from inscribed stones and it seems that the bulk of the Mesopotamian constellations were created within a relatively short interval from around 1300 to 1000 BC
Constellation
Constellation
Constellation
–
Babylonian tablet recording
Halley's comet in 164 BC.
Constellation
–
Chinese star map with a cylindrical projection (
Su Song)
5.
Bayer designation
–
A Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellations Latin name. The original list of Bayer designations contained 1,564 stars, most of the brighter stars were assigned their first systematic names by the German astronomer Johann Bayer in 1603, in his star atlas Uranometria. Bayer assigned a lower-case Greek letter, such as alpha, beta, gamma, for example, Aldebaran is designated α Tauri, which means Alpha of the constellation Taurus. A single constellation may contain fifty or more stars, but the Greek alphabet has only twenty-four letters, when these ran out, Bayer began using Latin letters, upper case A, followed by lower case b through z, for a total of another 24 letters. Bayer never went beyond z, but later added more designations using both upper and lower case Latin letters, the upper case letters following the lower case ones in general. Examples include s Carinae, d Centauri, G Scorpii, and N Velorum, the last upper-case letter used in this way was Q. Bayer catalogued only a few stars too far south to be seen from Germany, in most constellations, Bayer assigned Greek and Latin letters to stars within a constellation in rough order of apparent brightness, from brightest to dimmest. Since the brightest star in a majority of constellations is designated Alpha, in Bayers day, however, stellar brightness could not be measured precisely. Within each magnitude class, Bayer made no attempt to arrange stars by relative brightness, as a result, the brightest star in each class did not always get listed first in Bayers order. Occasionally the order looks quite arbitrary, of the 88 modern constellations, there are at least 30 in which Alpha is not the brightest star, and four of those lack an alpha star altogether. Orion provides an example of Bayers method. Bayer first designated Betelgeuse and Rigel, the two 1st-magnitude stars, as Alpha and Beta from north to south, with Betelgeuse coming ahead of Rigel, Bayer then repeated the procedure for the stars of the 2nd magnitude, labeling them from gamma through zeta in top-down order. The First to Rise in the East order is used in a number of instances, Castor and Pollux of Gemini may be an example of this, Pollux is brighter than Castor, but the latter rises earlier and was assigned alpha. In this case, Bayer may also have influenced by the traditional order of the mythological names Castor and Pollux. Although the brightest star in Draco is Eltanin, Thuban was assigned alpha by Bayer because, due to precession, sometimes there is no apparent order, as exemplified by the stars in Sagittarius, where Bayers designations appear almost random to the modern eye. Alpha and Beta Sagittarii are perhaps the most anomalously designated stars in the sky, the order of the letters assigned in Sagittarius does correspond to the magnitudes as illustrated on Bayers chart, but the latter do not agree with modern determinations of the magnitudes. Bayer designations added by later astronomers generally were ordered by magnitude, in Libra, for example, the new designations sigma, tau, and upsilon were chosen to avoid conflict with Bayers earlier designations, even though several stars with earlier letters are not as bright. In Cygnus, for example, Bayers fixed stars run through g, Bayer did not intend such labels as catalog designations, but some have survived to refer to astronomical objects, P Cygni for example is still used as a designation for Nova Cyg 1600
Bayer designation
–
Orion constellation map
6.
Exoplanet
–
An exoplanet or extrasolar planet is a planet that orbits a star other than the Sun. The first scientific detection of an exoplanet was in 1988, HARPS has discovered about a hundred exoplanets while the Kepler space telescope has found more than two thousand. Kepler has also detected a few thousand candidate planets, of which about 11% may be false positives, on average, there is at least one planet per star, with a percentage having multiple planets. About 1 in 5 Sun-like stars have an Earth-sized planet in the habitable zone, the least massive planet known is Draugr, which is about twice the mass of the Moon. There are planets that are so near to their star that they take only a few hours to orbit, some are so far out that it is difficult to tell whether they are gravitationally bound to the star. Almost all of the planets detected so far are within the Milky Way, the nearest exoplanet is Proxima Centauri b, located 4.2 light-years from Earth and orbiting Proxima Centauri, the closest star to the Sun. The discovery of exoplanets has intensified interest in the search for extraterrestrial life, there is special interest in planets that orbit in a stars habitable zone, where it is possible for liquid water, a prerequisite for life on Earth, to exist on the surface. The study of planetary habitability also considers a range of other factors in determining the suitability of a planet for hosting life. The rogue planets in the Milky Way possibly number in the billions, the convention for designating exoplanets is an extension of the system used for designating multiple-star systems as adopted by the International Astronomical Union. For exoplanets orbiting a star, the designation is normally formed by taking the name or, more commonly, designation of its parent star. The first planet discovered in a system is given the designation b, if several planets in the same system are discovered at the same time, the closest one to the star gets the next letter, followed by the other planets in order of orbital size. A provisional IAU-sanctioned standard exists to accommodate the designation of circumbinary planets, a limited number of exoplanets have IAU-sanctioned proper names. Various detection claims made in the century were rejected by astronomers. The first scientific detection of an exoplanet began in 1988, However, the first confirmed detection came in 1992, with the discovery of several terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a star was made in 1995. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method, in the eighteenth century the same possibility was mentioned by Isaac Newton in the General Scholium that concludes his Principia. Claims of exoplanet detections have been made since the nineteenth century, some of the earliest involve the binary star 70 Ophiuchi. In 1855 William Stephen Jacob at the East India Companys Madras Observatory reported that orbital anomalies made it highly probable that there was a body in this system
Exoplanet
–
Artist's view gives an impression of how commonly
planets orbit the
stars in the
Milky Way.
Exoplanet
–
The three known planets of the star
HR8799, as imaged by the
Hale Telescope. The light from the central star was blanked out by a
vector vortex coronagraph.
Exoplanet
–
2MASS J044144 is a
brown dwarf with a companion about 5–10 times the mass of Jupiter. It is not clear whether this companion object is a
sub-brown dwarf or a planet.
Exoplanet
–
Coronagraphic image of
AB Pictoris showing a companion (bottom left), which is either a brown dwarf or a massive planet. The data was obtained on 16 March 2003 with
NACO on the
VLT, using a 1.4 arcsec occulting mask on top of AB Pictoris.
7.
Polaris
–
Polaris, designated Alpha Ursae Minoris, commonly the North Star or Pole Star, is the brightest star in the constellation of Ursa Minor. It is very close to the celestial pole, making it the current northern pole star. The revised Hipparcos parallax gives a distance to Polaris of about 433 light-years, Polaris is a multiple star, comprising the main star in orbit with a smaller companion, the pair in orbit with Polaris B. There were once thought to be two more distant components—Polaris C and Polaris D—but these have been not to be physically associated with the Polaris system. Polaris Aa is a 4.5 solar mass F7 yellow supergiant of spectral type Ib and this is the first classical Cepheid to have a mass determined from its orbit. William Herschel discovered the star in 1780 while using a hand-built reflecting telescope, in 1929 it was discovered, by examining the spectrum of Polaris A, that it was a very close binary, with the secondary being a dwarf, which had been theorized in earlier observations. In January 2006, NASA released images, from the Hubble telescope, that showed the three members of the Polaris ternary system. The nearest dwarf star is in an orbit of only 18.5 au from Polaris A, about the distance between the Sun and Uranus), which explains why its light is swamped by its close and much brighter companion. Polaris A, the supergiant primary component, is a low-amplitude Population I classical Cepheid variable, cepheids constitute an important standard candle for determining distance, so Polaris, as the closest such star, is heavily studied. The variability of Polaris had been suspected since 1852, this variation was confirmed by Ejnar Hertzsprung in 1911, the range of brightness of Polaris during its pulsations is given as 1. 86–2.13, but the amplitude has changed since discovery. Prior to 1963, the amplitude was over 0.1 magnitude and was gradually decreasing. After 1966 it very rapidly decreased until it was less than 0.05 magnitude, since then and it has been reported that the amplitude is now increasing again, a reversal not seen in any other Cepheid. The period, roughly 4 days, has changed over time. It has steadily increased by around 4.5 seconds per year except for a hiatus in 1963–1965 and this was originally thought to be due to secular redward evolution across the Cepheid instability strip, but it may be due to interference between the primary and the first-overtone pulsation modes. Authors disagree on whether Polaris is a fundamental or first-overtone pulsator, the temperature of Polaris varies by only a small amount during its pulsations, but the amount of this variation is variable and unpredictable. The erratic changes of temperature and the amplitude of changes during each cycle, from less than 50 K to at least 170 K. Research reported in Science suggests that Polaris is 2.5 times brighter today than when Ptolemy observed it, because of its importance in celestial navigation, Polaris is known by numerous names. It became known as Polaris during the Renaissance, its derived from the Latin polaris of/near the pole
Polaris
–
Polaris as seen by the Hubble Space Telescope.
Polaris
–
This artist's concept shows three class F stars: supergiant Polaris A, dwarf Polaris Ab, and its distant dwarf companion, Polaris B
Polaris
–
A typical Northern Hemisphere star trail with Polaris in the center
Polaris
–
Ursa Major and Ursa Minor in relation to Polaris
8.
Meteor shower
–
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of debris called meteoroids entering Earths atmosphere at extremely high speeds on parallel trajectories. Most meteors are smaller than a grain of sand, so almost all of them disintegrate, intense or unusual meteor showers are known as meteor outbursts and meteor storms, which may produce greater than 1000 meteors an hour. The Meteor Data Centre lists about 600 suspected meteor showers of which about 100 are well established, the first great storm in modern times was the Leonids of November 1833. American Denison Olmsted explained the event most accurately, after spending the last weeks of 1833 collecting information he presented his findings in January 1834 to the American Journal of Science and Arts, published in January–April 1834, and January 1836. Work continued, however, coming to understand the nature of showers though the occurrences of storms perplexed researchers. In the 1890s, Irish astronomer George Johnstone Stoney and British astronomer Arthur Matthew Weld Downing, were the first to attempt to calculate the position of the dust at Earths orbit. They studied the dust ejected in 1866 by comet 55P/Tempel-Tuttle in advance of the anticipated Leonid shower return of 1898 and 1899, Meteor storms were anticipated, but the final calculations showed that most of the dust would be far inside of Earths orbit. The same results were independently arrived at by Adolf Berberich of the Königliches Astronomisches Rechen Institut in Berlin, although the absence of meteor storms that season confirmed the calculations, the advance of much better computing tools was needed to arrive at reliable predictions. In 1981 Donald K. Yeomans of the Jet Propulsion Laboratory reviewed the history of showers for the Leonids. A graph from it was adapted and re-published in Sky and Telescope and it showed relative positions of the Earth and Tempel-Tuttle and marks where Earth encountered dense dust. In 1985, E. D. Kondrateva and E. A. Reznikov of Kazan State University first correctly identified the years when dust was released which was responsible for several past Leonid meteor storms, in 1995, Peter Jenniskens predicted the 1995 Alpha Monocerotids outburst from dust trails. In anticipation of the 1999 Leonid storm, Robert H. McNaught, David Asher, in 2006 Jenniskens has published predictions for future dust trail encounters covering the next 50 years. Jérémie Vaubaillon continues to update predictions based on each year for the Institut de Mécanique Céleste et de Calcul des Éphémérides. Because meteor shower particles are all traveling in parallel paths, and at the same velocity and this radiant point is caused by the effect of perspective, similar to parallel railroad tracks converging at a single vanishing point on the horizon when viewed from the middle of the tracks. Meteor showers are almost always named after the constellation from which the appear to originate. This fixed point slowly moves across the sky during the due to the Earth turning on its axis. The radiant also moves slightly from night to night against the stars due to the Earth moving in its orbit around the sun
Meteor shower
–
Four-hour time lapse exposure of sky
Meteor shower
–
Leonids from space
Meteor shower
–
Diagram from 1872
Meteor shower
–
Meteor shower on chart
9.
Ursids
–
The Ursids meteor activity begins annually around December 17 and runs for a week plus, until the 25th or 26th. This meteor shower is named for its radiant point which is located near the star Beta Ursae Minoris in the constellation Ursa Minor, the Ursids were probably discovered by William F. Denning who observed them for several years around the start of the 20th century. While there were sporadic observations after, the first coordinated studies of shower didnt begin until Dr. A. Bečvář observed an outburst of 169 per hour in 1945, further observations in the 1970s and ongoing to current have established a relationship with comet 8P/Tuttle. Peter Jenniskens and Esko Lyytinen discovered that outbursts could happen when comet Tuttle was at aphelion because some meteorids get trapped in the 7/6 orbital resonance with Jupiter. Earlier observations described an average radiant of RA=217 deg, DEC=+76 deg, with maximum occurring at a longitude of 270.66 deg. The Ursids have a narrow stream, prompting veteran meteor observer, Norman W. McLeod. You have to be within 12 hours of maximum to see much, gary Kronks Meteor Showers Online - Ursids International Meteor Organisation Calendar - Fall 2005 NASA Ursid Airborne Campaign 2011 Ursids Radio results Ursids at Constellation Guide
Ursids
–
Radiant of the Ursids meteors circled
10.
Draco (constellation)
–
Draco is a constellation in the far northern sky. Its name is Latin for dragon and it was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations today. The north pole of the ecliptic is in Draco, Draco is circumpolar, and can be seen all year from northern latitudes. Thuban was the pole star from 3942 BC, when it moved farther north than Theta Boötis. The Egyptian Pyramids were designed to have one side facing north, with an entrance passage geometrically aligned so that Thuban would be visible at night, due to the effects of precession, it will again be the pole star around the year AD21000. It is a giant star of magnitude 3.7,309 light-years from Earth. The traditional name of Alpha Draconis, Thuban, means head of the serpent, there are two other stars under magnitude 3 in Draco. The brighter of the two, and the brightest star in Draco, is Gamma Draconis, traditionally called Etamin or Eltanin and it is an orange giant star of magnitude 2.2,148 light-years from Earth. The aberration of starlight was discovered in 1728 when James Bradley observed Gamma Draconis, beta Draconis, traditionally called Rastaban, is a yellow giant star of magnitude 2.8,362 light-years from Earth. Its name shares a meaning with Thuban, head of the serpent, Draco is home to several double stars and binary stars. η Draconis is a star with a yellow-hued primary of magnitude 2.8. The two are separated by 4.8 arcseconds, mu Draconis, traditionally called Alrakis, is a binary star with two white components. Magnitude 5.6 and 5.7, the two orbit each other every 670 years. The Alrakis system is 88 light-years from Earth, nu Draconis is a similar binary star with two white components,100 light-years from Earth. Both components are of magnitude 4.9 and can be distinguished in an amateur telescope or a pair of binoculars. Omicron Draconis is a double star divisible in small telescopes, the primary is an orange giant of magnitude 4.6,322 light-years from Earth. The secondary is of magnitude 7.8, psi Draconis is a binary star divisible in binoculars and small amateur telescopes,72 light-years from Earth. The primary is a star of magnitude 4.6
Draco (constellation)
–
The constellation Draco as it can be seen by the naked eye.
Draco (constellation)
–
List of stars in Draco
Draco (constellation)
–
PGC 39058, a dwarf galaxy found within the Draco constellation – picture taken by ESA/Hubble & NASA.
Draco (constellation)
–
Draco coils around the north celestial pole, as depicted in Urania's Mirror, a set of constellation cards published in London c.1825
11.
Camelopardalis
–
Camelopardalis /kəˌmɛləˈpɑːrdəlᵻs/ or the Giraffe constellation is a large, faint grouping of stars in the northern sky. The constellation was introduced in 1612 by Petrus Plancius, some older astronomy books give an alternative spelling of the name, Camelopardalus, Camelopardi as well as Camelopardus. Although Camelopardalis is the 18th largest constellation, it is not a bright constellation. In fact, it contains four stars below magnitude 5.0. α Cam is a supergiant star of magnitude 4.3,5000 light-years from Earth. It is one of the most distant stars easily visible with the naked eye, β Cam is the brightest star in Camelopardalis with an apparent magnitude of 4.03. This star is a star, with components of magnitudes 4.0 and 8.6. The primary is a yellow-hued supergiant 1000 light-years from Earth,11 Cam is a star of magnitude 5.2,650 light-years from Earth. It is very close to magnitude 6.112 Cam, also 650 light-years from Earth, Σ1694 is a binary star 300 light-years from Earth. Both components have a hue, the primary is of magnitude 5.4. CS Cam is the second brightest star, though it has neither a Bayer nor a Flamsteed designation and it is of magnitude 4.21 and is slightly variable. Z Cam is frequently observed as part of a program of AAVSO and it is the prototype of Z Camelopardalis variable stars. Other variable stars are U Camelopardalis, VZ Camelopardalis, and Mira variables T Camelopardalis, X Camelopardalis, RU Camelopardalis is one of the brighter Type II Cepheids visible in the night sky. In 2011 a supernova was discovered in the constellation, Camelopardalis is in the part of the celestial sphere facing away from the galactic plane. Accordingly, many distant galaxies are visible within its borders, NGC2403 is a galaxy in the M81 group of galaxies, located approximately 12 million light-years from Earth with a redshift of 0.00043. It is classified as being between an elliptical and a spiral galaxy because it has faint arms and a central bulge. NGC2403 was first discovered by the 18th century astronomer William Herschel and it has an integrated magnitude of 8.0 and is approximately 0. 25° long. NGC1502 is a magnitude 6.9 open cluster about 3,000 light years from Earth and it has about 45 bright members, and features a double star of magnitude 7.0 at its center
Camelopardalis
–
The constellation Camelopardalis as it can be seen by the naked eye.
Camelopardalis
–
List of stars in Camelopardalis
Camelopardalis
–
Camelopardalis as depicted in
Urania's Mirror, a set of constellation cards published in London c.1825. Above it are shown the now-abandoned constellations of
Tarandus and
Custos Messium.
12.
Big Dipper
–
The Big Dipper or Plough is an asterism consisting of the seven brightest stars of the constellation Ursa Major, six of them are of second magnitude and one, Megrez, of third magnitude. Four define a bowl or body and three define a handle or head and it is recognized as a distinct grouping in many cultures. The North Star, the current northern pole star and the tip of the handle of the Little Dipper and this makes it useful in celestial navigation. The constellation of Ursa Major has been seen as a bear by many distinct civilizations and this may stem from a common oral tradition stretching back for thousands of years. Using statistical and phylogenetic tools, Julien dHuy reconstructs the following Palaeolithic state of the story, There is an animal that is a horned herbivore, the hunt proceeds to the sky. The animal is alive when it is transformed into a constellation-- It forms the Big Dipper. In Canada and the United States, the asterism is known as the Big Dipper because the stars can be seen to follow the rough outline of a spoon or dipper. There are seven stars in the Dipper, proceeding from the handle to the bowl, Alkaid, Mizar, Alioth, Megrez, Phecda, Merak, a widespread Native American figuration had the bowl as a bear. Some groups considered the handle to be three cubs following their mother, while others pictured three hunters tracking the bear, the Anishinaabe or Ojibway First Nation know the Big Dipper as the Fisher Star after the small mammal known as the fisher. In both Ireland and the United Kingdom, this pattern is known as the Plough, the symbol of the Starry Plough has been used as a political symbol by Irish Republican and left wing movements. Another former name was the Great Wain, in northern England, it is occasionally still known as the Butchers Cleaver, and in the northeast, as Charlies Wagon. This derives from the earlier Charless Wain and Charles his Wain, a folk etymology holds that this derived from Charlemagne, but the name is common to all the Germanic languages and intended the churls wagon, in contrast with the womens wagon. An older Odins Wain may have preceded these Nordic designations, in German, it is known as the Great Wagon and, less often, the Great Bear. In Scandinavia, it is known by variations of Charless Wagon, in Dutch, its official name is the Great Bear, but it is popularly known as the Saucepan. In Italian, too, it is called the Great Wagon, in Finnish, the figure is known as the Salmon Net and widely used as a cultural symbol. The brown bear in Finnish actually became known as otava, Book XVIII of Homers Iliad mentions it as the Bear, which men also call the Wain. In Latin, these seven stars were known as the Seven Oxen, triōnēs is a hapax legomenon, occurring only in a single passage by Varro, where he glosses it as meaning plough oxen. The derivation is acceptable but the meaning, if Varro is right that it derives from terō, is surely threshing oxen, the seven stars wheel around the pole star like oxen on a threshing floor
Big Dipper
–
The Big Dipper seen from
Kauai.
Big Dipper
–
The
asterism of the Big Dipper (shown in this star map in green) lies within the constellation of
Ursa Major.
Big Dipper
–
The "Great Wain" seen from
Berlin (2011)
Big Dipper
–
The Big Dipper seen from Spain
13.
Ptolemy
–
Claudius Ptolemy was a Greek writer, known as a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in the city of Alexandria in the Roman province of Egypt, wrote in Koine Greek, beyond that, few reliable details of his life are known. His birthplace has been given as Ptolemais Hermiou in the Thebaid in a statement by the 14th-century astronomer Theodore Meliteniotes. This is a very late attestation, however, and there is no reason to suppose that he ever lived elsewhere than Alexandria. Ptolemy wrote several treatises, three of which were of importance to later Byzantine, Islamic and European science. The first is the astronomical treatise now known as the Almagest, although it was entitled the Mathematical Treatise. The second is the Geography, which is a discussion of the geographic knowledge of the Greco-Roman world. The third is the treatise in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day. This is sometimes known as the Apotelesmatika but more known as the Tetrabiblos from the Greek meaning Four Books or by the Latin Quadripartitum. The name Claudius is a Roman nomen, the fact that Ptolemy bore it indicates he lived under the Roman rule of Egypt with the privileges and political rights of Roman citizenship. It would have suited custom if the first of Ptolemys family to become a citizen took the nomen from a Roman called Claudius who was responsible for granting citizenship, if, as was common, this was the emperor, citizenship would have been granted between AD41 and 68. The astronomer would also have had a praenomen, which remains unknown and it occurs once in Greek mythology, and is of Homeric form. All the kings after him, until Egypt became a Roman province in 30 BC, were also Ptolemies, abu Mashar recorded a belief that a different member of this royal line composed the book on astrology and attributed it to Ptolemy. The correct answer is not known”, Ptolemy wrote in Greek and can be shown to have utilized Babylonian astronomical data. He was a Roman citizen, but most scholars conclude that Ptolemy was ethnically Greek and he was often known in later Arabic sources as the Upper Egyptian, suggesting he may have had origins in southern Egypt. Later Arabic astronomers, geographers and physicists referred to him by his name in Arabic, Ptolemys Almagest is the only surviving comprehensive ancient treatise on astronomy. Ptolemy presented his models in convenient tables, which could be used to compute the future or past position of the planets. The Almagest also contains a catalogue, which is a version of a catalogue created by Hipparchus
Ptolemy
–
Engraving of a crowned Ptolemy being guided by the muse Astronomy, from Margarita Philosophica by
Gregor Reisch, 1508. Although
Abu Ma'shar believed Ptolemy to be one of the
Ptolemies who ruled Egypt after the conquest of
Alexander the title ‘King Ptolemy’ is generally viewed as a mark of respect for Ptolemy's elevated standing in science.
Ptolemy
–
Early
Baroque artist's rendition
Ptolemy
–
A 15th-century manuscript copy of the
Ptolemy world map, reconstituted from Ptolemy's Geography (circa 150), indicating the countries of "
Serica " and "Sinae" (
China) at the extreme east, beyond the island of "Taprobane" (
Sri Lanka, oversized) and the "Aurea Chersonesus" (
Malay Peninsula).
Ptolemy
–
Prima Europe tabula. A C15th copy of Ptolemy's map of Britain
14.
88 modern constellations
–
In modern astronomy, the sky is divided into 88 regions called constellations, generally based on the asterisms of Greek and Roman mythology. Those along the ecliptic are the constellations of the zodiac, the ancient Sumerians, and later the Greeks, established most of the northern constellations in international use today. Not all of these proposals caught on, but in 1922, after this, Eugène Joseph Delporte drew up precise boundaries for each constellation, so that every point in the sky belonged to exactly one constellation. Some constellations are no longer recognized by the International Astronomical Union, most notable is Argo Navis, which was one of Ptolemys original 48 constellations. The 88 constellations depict 42 animals,29 inanimate objects and 17 humans or mythological characters, each of the IAU constellations has an official 3 letter abbreviation. They are actually abbreviations of the form of the constellation names. The majority of the abbreviations are just the first three letters of the constellation, with the first character capitalised, Ori for Orion, Ara for Ara/Arae, Com for Coma Berenices. When letters are taken from the word of a two-word name. The abbreviations are unambiguous, with two exceptions, Leo for the constellation Leo could be mistaken for Leo Minor, and Tri for Triangulum could be mistaken for Triangulum Australe. For help with the literary English pronunciations, see the pronunciation key, there is considerable diversity in how Latinate names are pronounced in English. For traditions closer to the original, see Latin spelling and pronunciation, the Family column refers to the constellation families introduced by Donald Menzel in 1975. Various other unofficial patterns have existed alongside the constellations, examples include the Big Dipper/Plough and the Northern Cross. Some ancient asterisms, for example Coma Berenices, Serpens, http, //www. ianridpath. com/startales/contents. htm – Ian Ridpaths Star Tales. Http, //cdsarc. u-strasbg. fr/viz-bin/Cat. cat=VI/49 – CDSs archive of constellation boundaries, the text file constbnd. dat gives the 1875.0 coordinates of the vertices of the constellation regions, together with the constellations adjacent to each boundary segment
88 modern constellations
–
Equirectangular plot of declination vs right ascension of the modern constellations with a dotted line denoting the ecliptic. Constellations are colour-coded by family and year established. (detailed view)
15.
Navigation
–
Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four categories, land navigation, marine navigation, aeronautic navigation. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks, all navigational techniques involve locating the navigators position compared to known locations or patterns. Navigation, in a sense, can refer to any skill or study that involves the determination of position and direction. In this sense, navigation includes orienteering and pedestrian navigation, for information about different navigation strategies that people use, visit human navigation. In the European medieval period, navigation was considered part of the set of seven mechanical arts, early Pacific Polynesians used the motion of stars, weather, the position of certain wildlife species, or the size of waves to find the path from one island to another. Maritime navigation using scientific instruments such as the mariners astrolabe first occurred in the Mediterranean during the Middle Ages, the perfecting of this navigation instrument is attributed to Portuguese navigators during early Portuguese discoveries in the Age of Discovery. Open-seas navigation using the astrolabe and the compass started during the Age of Discovery in the 15th century, the Portuguese began systematically exploring the Atlantic coast of Africa from 1418, under the sponsorship of Prince Henry. In 1488 Bartolomeu Dias reached the Indian Ocean by this route, in 1492 the Spanish monarchs funded Christopher Columbuss expedition to sail west to reach the Indies by crossing the Atlantic, which resulted in the Discovery of America. In 1498, a Portuguese expedition commanded by Vasco da Gama reached India by sailing around Africa, soon, the Portuguese sailed further eastward, to the Spice Islands in 1512, landing in China one year later. The fleet of seven ships sailed from Sanlúcar de Barrameda in Southern Spain in 1519, crossed the Atlantic Ocean, some ships were lost, but the remaining fleet continued across the Pacific making a number of discoveries including Guam and the Philippines. By then, only two galleons were left from the original seven, the Victoria led by Elcano sailed across the Indian Ocean and north along the coast of Africa, to finally arrive in Spain in 1522, three years after its departure. The Trinidad sailed east from the Philippines, trying to find a path back to the Americas. He arrived in Acapulco on October 8,1565, the term stems from 1530s, from Latin navigationem, from navigatus, pp. of navigare to sail, sail over, go by sea, steer a ship, from navis ship and the root of agere to drive. Roughly, the latitude of a place on Earth is its angular distance north or south of the equator, latitude is usually expressed in degrees ranging from 0° at the Equator to 90° at the North and South poles. The height of Polaris in degrees above the horizon is the latitude of the observer, similar to latitude, the longitude of a place on Earth is the angular distance east or west of the prime meridian or Greenwich meridian. Longitude is usually expressed in degrees ranging from 0° at the Greenwich meridian to 180° east and west, sydney, for example, has a longitude of about 151° east. New York City has a longitude of 74° west, for most of history, mariners struggled to determine longitude
Navigation
–
Table of geography, hydrography, and navigation, from the 1728
Cyclopaedia
Navigation
–
Dead reckoning or DR, in which one advances a prior position using the ship's course and speed. The new position is called a DR position. It is generally accepted that only course and speed determine the DR position. Correcting the DR position for
leeway, current effects, and steering error result in an estimated position or EP. An
inertial navigator develops an extremely accurate EP.
Navigation
–
Pilotage involves navigating in restricted waters with frequent determination of position relative to geographic and hydrographic features.
Navigation
–
Celestial navigation involves reducing celestial measurements to lines of position using tables,
spherical trigonometry, and
almanacs.
16.
North Star
–
Polaris, designated Alpha Ursae Minoris, commonly the North Star or Pole Star, is the brightest star in the constellation of Ursa Minor. It is very close to the celestial pole, making it the current northern pole star. The revised Hipparcos parallax gives a distance to Polaris of about 433 light-years, Polaris is a multiple star, comprising the main star in orbit with a smaller companion, the pair in orbit with Polaris B. There were once thought to be two more distant components—Polaris C and Polaris D—but these have been not to be physically associated with the Polaris system. Polaris Aa is a 4.5 solar mass F7 yellow supergiant of spectral type Ib and this is the first classical Cepheid to have a mass determined from its orbit. William Herschel discovered the star in 1780 while using a hand-built reflecting telescope, in 1929 it was discovered, by examining the spectrum of Polaris A, that it was a very close binary, with the secondary being a dwarf, which had been theorized in earlier observations. In January 2006, NASA released images, from the Hubble telescope, that showed the three members of the Polaris ternary system. The nearest dwarf star is in an orbit of only 18.5 au from Polaris A, about the distance between the Sun and Uranus), which explains why its light is swamped by its close and much brighter companion. Polaris A, the supergiant primary component, is a low-amplitude Population I classical Cepheid variable, cepheids constitute an important standard candle for determining distance, so Polaris, as the closest such star, is heavily studied. The variability of Polaris had been suspected since 1852, this variation was confirmed by Ejnar Hertzsprung in 1911, the range of brightness of Polaris during its pulsations is given as 1. 86–2.13, but the amplitude has changed since discovery. Prior to 1963, the amplitude was over 0.1 magnitude and was gradually decreasing. After 1966 it very rapidly decreased until it was less than 0.05 magnitude, since then and it has been reported that the amplitude is now increasing again, a reversal not seen in any other Cepheid. The period, roughly 4 days, has changed over time. It has steadily increased by around 4.5 seconds per year except for a hiatus in 1963–1965 and this was originally thought to be due to secular redward evolution across the Cepheid instability strip, but it may be due to interference between the primary and the first-overtone pulsation modes. Authors disagree on whether Polaris is a fundamental or first-overtone pulsator, the temperature of Polaris varies by only a small amount during its pulsations, but the amount of this variation is variable and unpredictable. The erratic changes of temperature and the amplitude of changes during each cycle, from less than 50 K to at least 170 K. Research reported in Science suggests that Polaris is 2.5 times brighter today than when Ptolemy observed it, because of its importance in celestial navigation, Polaris is known by numerous names. It became known as Polaris during the Renaissance, its derived from the Latin polaris of/near the pole
North Star
–
A French "navisphere": a type of celestial globe formerly used for navigation at sea
North Star
–
A
long exposure (45 min.) photo of Polaris and
neighbouring stars, taken at Ehrenbürg (
Franconia), 2001.
17.
Star
–
It is primarily present in steroid-producing cells, including theca cells and luteal cells in the ovary, Leydig cells in the testis and cell types in the adrenal cortex. The aqueous phase between two membranes cannot be crossed by the lipophilic cholesterol, unless certain proteins assist in this process. It is now clear that this process is mediated by the action of StAR. The mechanism by which StAR causes cholesterol movement remains unclear as it appears to act from the outside of the mitochondria, some involve StAR transferring cholesterol itself like a shuttle. Another notion is that it causes cholesterol to be kicked out of the membrane to the inner. StAR may also promote the formation of contact sites between the outer and inner mitochondrial membranes to allow cholesterol influx, another suggests that StAR acts in conjunction with PBR, causing the movement of Cl− out of the mitochondria to facilitate contact site formation. However, evidence for an interaction between StAR and PBR remains elusive, in humans, the gene for StAR is located on chromosome 8p11.2 and the protein has 285 amino acids. The signal sequence of StAR that targets it to the mitochondria is clipped off in two steps with import into the mitochondria, phosphorylation at the serine at position 195 increases its activity. The domain of StAR important for promoting cholesterol transfer is the StAR-related transfer domain, StAR is the prototypic member of the START domain family of proteins and is thus also known as STARD1 for START domain-containing protein 1. It is hypothesized that the START domain forms a pocket in StAR that binds single cholesterol molecules for delivery to P450scc, the closest homolog to StAR is MLN64. Together they comprise the StarD1/D3 subfamily of START domain-containing proteins, StAR is a mitochondrial protein that is rapidly synthesized in response to stimulation of the cell to produce steroid. Hormones that stimulate its production depend on the type and include luteinizing hormone, ACTH. At the cellular level, StAR is synthesized typically in response to activation of the second messenger system. StAR has thus far found in all tissues that can produce steroids, including the adrenal cortex, the gonads, the brain. One known exception is the human placenta, mutations in the gene for StAR cause lipoid congenital adrenal hyperplasia, in which patients produce little steroid and can die shortly after birth. Mutations that less severely affect the function of StAR result in nonclassic lipoid CAH or familial glucocorticoid deficiency type 3, all known mutations disrupt StAR function by altering its START domain. In the case of StAR mutation, the phenotype does not present until birth since human placental steroidogenesis is independent of StAR. At the cellular level, the lack of StAR results in an accumulation of lipid within cells
Star
18.
Callimachus
–
Callimachus was a native of the Greek colony of Cyrene, Libya. He was a poet, critic and scholar at the Library of Alexandria and enjoyed the patronage of the Egyptian–Greek Pharaohs Ptolemy II Philadelphus. Although he was never made chief librarian, he was responsible for producing a survey based upon the contents of the Library. This, his Pinakes,120 volumes long, provided the foundation for work on the history of Greek literature. As one of the earliest critic-poets, he typifies Hellenistic scholarship, Callimachus was of Libyan Greek origin. He was named after his grandfather, an elder Callimachus, who was regarded by the Cyrenaean citizens and had served as a general. Callimachus married the daughter of a Greek man called Euphrates who came from Syracuse, however, it is unknown if they had children. In later years, he was educated in Athens, when he returned to North Africa, he moved to Alexandria. Elitist and erudite, claiming to abhor all common things, Callimachus is best known for his poems and epigrams. During the Hellenistic period, a trend in Greek-language poetry was to reject epics modelled after Homer. Big book, big evil is another saying attributed to him, often thought to be attacking long, Callimachus also wrote poems in praise of his royal patrons, and a wide variety of other poetic styles, as well as prose and criticism. Some classicists, including Peter Green, speculate that this contributed to the long feud. Though Callimachus was an opponent of big books, the Suda puts his number of works at 800, suggesting that he found large quantities of small works more acceptable. In the first three books at least, the formula appears to ask a question of the Muse, of the form, Why, on Paros, why, at Argos is a month named for lambs. Why, at Leucas, does the image of Artemis have a mortar on its head, a series of questions can be reconstituted from the fragments. One passage of the Aetia, the so-called Coma Berenices, has been reconstructed from papyrus remains, the extant hymns are extremely learned, and written in a style that some have criticised as labored and artificial. The epigrams are more widely respected, and several have been incorporated into the Greek Anthology, according to Quintilian he was the chief of the elegiac poets, his elegies were highly esteemed by the Romans, and imitated by Ovid, Catullus, and especially Sextus Propertius. Many modern classicists hold Callimachus in high regard for his influence on Latin poetry
Callimachus
–
A papyrus of Callimachus' Aetia (Pfeiffer fr. 178 =
P.Oxy. XI 1362 fr. 1 col. i, 1st century AD)
19.
Homer
–
Homer is the name ascribed by the ancient Greeks to the semi-legendary author of the Iliad and the Odyssey, two epic poems which are the central works of Greek literature. The Odyssey focuses on the home of Odysseus, king of Ithaca. Many accounts of Homers life circulated in classical antiquity, the most widespread being that he was a bard from Ionia. The modern scholarly consensus is that these traditions do not have any historical value, the Homeric question - by whom, when, where and under what circumstances were the Iliad and Odyssey composed - continues to be debated. Broadly speaking, modern scholarly opinion on the authorship question falls into two camps, one group holds that most of the Iliad and the Odyssey is the work of a single poet of genius. The other considers the Homeric poems to be the crystallization of a process of working and re-working by many contributors and it is generally accepted that the poems were composed at some point around the late eighth or early seventh century B. C. Most researchers believe that the poems were transmitted orally. The Homeric epics were the greatest influence on ancient Greek culture and education, to Plato, the chronological period of Homer depends on the meaning to be assigned to the word Homer. Was Homer a single person, an imaginary person representing a group of poets and this information is often called the world of Homer. The Homeric period would in that cover a number of historical periods, especially the Mycenaean Age. Considered word-for-word, the texts as we know them are the product of the scholars of the last three centuries. Each edition of the Iliad or Odyssey is a different, as the editors rely on different manuscripts and fragments. The term accuracy reveals a belief in an original uniform text. The manuscripts of the work currently available date to no earlier than the 10th century. These are at the end of a missing thousand-year chain of copies made as each generation of manuscripts disintegrated or were lost or destroyed and these numerous manuscripts are so similar that a single original can be postulated. The time gap in the chain is bridged by the scholia, or notes, on the existing manuscripts, librarian of the Library of Alexandria, he had noticed a wide divergence in the works attributed to Homer, and was trying to restore a more authentic copy. He had collected several manuscripts, which he named, the Sinopic, the one he selected for correction was the koine, which Murray translates as the Vulgate. Aristarchus was known for his selection of material
Homer
–
Idealized portrayal of Homer dating to the
Hellenistic period.
British Museum.
Homer
–
Part of an 11th-century manuscript, "the Townley Homer". The writing on the top and right side are
scholia.
Homer
–
Homer and His Guide, by
William-Adolphe Bouguereau (1825–1905), portraying Homer on
Mount Ida, beset by dogs and guided by the goatherder Glaucus (as told in
Pseudo-Herodotus)
Homer
–
Raphael 's inspired Homer on
Mount Parnassus.
20.
Thales
–
Thales of Miletus was a pre-Socratic Greek/Phoenician philosopher, mathematician and astronomer from Miletus in Asia Minor. He was one of the Seven Sages of Greece, Thales is recognized for breaking from the use of mythology to explain the world and the universe, and instead explaining natural objects and phenomena by theories and hypothesis, i. e. science. Aristotle reported Thales hypothesis that the principle of nature and the nature of matter was a single material substance. In mathematics, Thales used geometry to calculate the heights of pyramids and he is the first known individual to use deductive reasoning applied to geometry, by deriving four corollaries to Thales theorem. He is the first known individual to whom a mathematical discovery has been attributed, the ancient source, Apollodorus of Athens, writing during the 2nd century BCE, thought Thales was born about the year 625 BCE. The dates of Thales life are not exactly known, but are roughly established by a few events mentioned in the sources. According to Herodotus Thales predicted the eclipse of May 28,585 BC. Diogenes Laërtius quotes the chronicle of Apollodorus of Athens as saying that Thales died at the age of 78 during the 58th Olympiad and attributes his death to heat stroke while watching the games. Plutarch had earlier told this version, Solon visited Thales and asked him why he remained single, nevertheless, several years later, anxious for family, he adopted his nephew Cybisthus. Thales involved himself in many activities, taking the role of an innovator, some say that he left no writings, others say that he wrote On the Solstice and On the Equinox. Diogenes Laërtius quotes two letters from Thales, one to Pherecydes of Syros, offering to review his book on religion, Thales identifies the Milesians as Athenian colonists. He was aware of the existence of the lodestone, and was the first to be connected to knowledge of this in history, according to Aristotle, Thales thought lodestones had souls, because iron is attracted to them. According to Hieronymus, historically quoted by Diogenes Laertius, Thales found the height of pyramids by comparison between the lengths of the shadows cast by a person and by the pyramids, several anecdotes suggest Thales was not just a philosopher, but also a businessman. A story, with different versions, recounts how Thales achieved riches from an olive harvest by prediction of the weather, in one version, he bought all the olive presses in Miletus after predicting the weather and a good harvest for a particular year. Thales’ political life had mainly to do with the involvement of the Ionians in the defense of Anatolia against the power of the Persians. In neighbouring Lydia, a king had come to power, Croesus and he had conquered most of the states of coastal Anatolia, including the cities of the Ionians. The story is told in Herodotus, the war endured for five years, but in the sixth an eclipse of the Sun spontaneously halted a battle in progress. It seems that Thales had predicted this solar eclipse, the Seven Sages were most likely already in existence, as Croesus was also heavily influenced by Solon of Athens, another sage
Thales
–
Thales of Miletus
Thales
–
An olive mill and an olive press dating from Roman times in
Capernaum, Israel.
Thales
–
Total
eclipse of the
Sun
Thales
–
The Ionic Stoa on the Sacred Way in Miletus
21.
Classical antiquity
–
It is the period in which Greek and Roman society flourished and wielded great influence throughout Europe, North Africa and Southwestern Asia. Conventionally, it is taken to begin with the earliest-recorded Epic Greek poetry of Homer, and continues through the emergence of Christianity and it ends with the dissolution of classical culture at the close of Late Antiquity, blending into the Early Middle Ages. Such a wide sampling of history and territory covers many disparate cultures, Classical antiquity may refer also to an idealised vision among later people of what was, in Edgar Allan Poes words, the glory that was Greece, and the grandeur that was Rome. The culture of the ancient Greeks, together with influences from the ancient Near East, was the basis of art, philosophy, society. The earliest period of classical antiquity takes place before the background of gradual re-appearance of historical sources following the Bronze Age collapse, the 8th and 7th centuries BC are still largely proto-historical, with the earliest Greek alphabetic inscriptions appearing in the first half of the 8th century. Homer is usually assumed to have lived in the 8th or 7th century BC, in the same period falls the traditional date for the establishment of the Ancient Olympic Games, in 776 BC. The Phoenicians originally expanded from Canaan ports, by the 8th century dominating trade in the Mediterranean, carthage was founded in 814 BC, and the Carthaginians by 700 BC had firmly established strongholds in Sicily, Italy and Sardinia, which created conflicts of interest with Etruria. The Etruscans had established control in the region by the late 7th century BC, forming the aristocratic. According to legend, Rome was founded on April 21,753 BC by twin descendants of the Trojan prince Aeneas, Romulus and Remus. As the city was bereft of women, legend says that the Latins invited the Sabines to a festival and stole their unmarried maidens, leading to the integration of the Latins and the Sabines. Archaeological evidence indeed shows first traces of settlement at the Roman Forum in the mid-8th century BC, the seventh and final king of Rome was Tarquinius Superbus. As the son of Tarquinius Priscus and the son-in-law of Servius Tullius, Superbus was of Etruscan birth and it was during his reign that the Etruscans reached their apex of power. Superbus removed and destroyed all the Sabine shrines and altars from the Tarpeian Rock, the people came to object to his rule when he failed to recognize the rape of Lucretia, a patrician Roman, at the hands of his own son. Lucretias kinsman, Lucius Junius Brutus, summoned the Senate and had Superbus, after Superbus expulsion, the Senate voted to never again allow the rule of a king and reformed Rome into a republican government in 509 BC. In fact the Latin word Rex meaning King became a dirty and hated throughout the Republic. In 510, Spartan troops helped the Athenians overthrow the tyrant Hippias, cleomenes I, king of Sparta, put in place a pro-Spartan oligarchy conducted by Isagoras. Greece entered the 4th century under Spartan hegemony, but by 395 BC the Spartan rulers removed Lysander from office, and Sparta lost her naval supremacy. Athens, Argos, Thebes and Corinth, the two of which were formerly Spartan allies, challenged Spartan dominance in the Corinthian War, which ended inconclusively in 387 BC
Classical antiquity
–
The
Parthenon is one of the most iconic symbols of the classical era, exemplifying ancient Greek culture
22.
Celestial pole
–
The north and south celestial poles are the two imaginary points in the sky where the Earths axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently directly overhead to an observer at the Earths North Pole and South Pole respectively. As the Earth spins on its axis, the two celestial poles remain fixed in the sky, and all other points appear to rotate around them, completing one circuit per day. The celestial poles are also the poles of the equatorial coordinate system, meaning they have declinations of +90 degrees. The celestial poles do not remain permanently fixed against the background of the stars, because of a phenomenon known as the precession of the equinoxes, the poles trace out circles on the celestial sphere, with a period of about 25,700 years. The Earths axis is subject to other complex motions which cause the celestial poles to shift slightly over cycles of varying lengths, see nutation, polar motion. Finally, over long periods the positions of the stars themselves change. An analogous concept applies to other planets, a planets celestial poles are the points in the sky where the projection of the axis of rotation intersects the celestial sphere. These points vary because different planets axes are oriented differently, Celestial bodies other than Earth also have similarly defined celestial poles. The north celestial pole currently is within a degree of the bright star Polaris, Polaris can, of course, only be seen from locations in the northern hemisphere. Polaris is near the pole for only a small fraction of the 25. It will remain a good approximation for about 1,000 years, to find Polaris, face north and locate the Big Dipper and Little Dipper asterisms. Looking at the cup part of the Big Dipper, imagine that the two stars at the edge of the cup form a line pointing upward out of the cup. This line points directly at the star at the tip of the Little Dippers handle and that star is Polaris, the North Star. The south celestial pole is only from the southern hemisphere. It lies in the dim constellation Octans, the Octant, sigma Octantis is identified as the south pole star, over a degree away from the pole, but with a magnitude of 5.5 it is barely visible on a clear night. The south celestial pole can be located from the Southern Cross, draw an imaginary line from γ Crucis to α Crucis—the two stars at the extreme ends of the long axis of the cross—and follow this line through the sky. This point is 5 or 6 degrees from the celestial pole
Celestial pole
–
Over the course of an evening, stars appear to rotate about the north celestial pole. Polaris, within a degree of the pole, is the single nearly-stationary star just to the right of the center of this image.
Celestial pole
–
The north and south celestial poles and their relation to
axis of rotation,
plane of orbit and
axial tilt.
Celestial pole
–
Celestial South Pole over the
Very Large Telescope.
Celestial pole
–
Locating the south celestial pole
23.
North star
–
Polaris, designated Alpha Ursae Minoris, commonly the North Star or Pole Star, is the brightest star in the constellation of Ursa Minor. It is very close to the celestial pole, making it the current northern pole star. The revised Hipparcos parallax gives a distance to Polaris of about 433 light-years, Polaris is a multiple star, comprising the main star in orbit with a smaller companion, the pair in orbit with Polaris B. There were once thought to be two more distant components—Polaris C and Polaris D—but these have been not to be physically associated with the Polaris system. Polaris Aa is a 4.5 solar mass F7 yellow supergiant of spectral type Ib and this is the first classical Cepheid to have a mass determined from its orbit. William Herschel discovered the star in 1780 while using a hand-built reflecting telescope, in 1929 it was discovered, by examining the spectrum of Polaris A, that it was a very close binary, with the secondary being a dwarf, which had been theorized in earlier observations. In January 2006, NASA released images, from the Hubble telescope, that showed the three members of the Polaris ternary system. The nearest dwarf star is in an orbit of only 18.5 au from Polaris A, about the distance between the Sun and Uranus), which explains why its light is swamped by its close and much brighter companion. Polaris A, the supergiant primary component, is a low-amplitude Population I classical Cepheid variable, cepheids constitute an important standard candle for determining distance, so Polaris, as the closest such star, is heavily studied. The variability of Polaris had been suspected since 1852, this variation was confirmed by Ejnar Hertzsprung in 1911, the range of brightness of Polaris during its pulsations is given as 1. 86–2.13, but the amplitude has changed since discovery. Prior to 1963, the amplitude was over 0.1 magnitude and was gradually decreasing. After 1966 it very rapidly decreased until it was less than 0.05 magnitude, since then and it has been reported that the amplitude is now increasing again, a reversal not seen in any other Cepheid. The period, roughly 4 days, has changed over time. It has steadily increased by around 4.5 seconds per year except for a hiatus in 1963–1965 and this was originally thought to be due to secular redward evolution across the Cepheid instability strip, but it may be due to interference between the primary and the first-overtone pulsation modes. Authors disagree on whether Polaris is a fundamental or first-overtone pulsator, the temperature of Polaris varies by only a small amount during its pulsations, but the amount of this variation is variable and unpredictable. The erratic changes of temperature and the amplitude of changes during each cycle, from less than 50 K to at least 170 K. Research reported in Science suggests that Polaris is 2.5 times brighter today than when Ptolemy observed it, because of its importance in celestial navigation, Polaris is known by numerous names. It became known as Polaris during the Renaissance, its derived from the Latin polaris of/near the pole
North star
–
A French "navisphere": a type of celestial globe formerly used for navigation at sea
North star
–
A
long exposure (45 min.) photo of Polaris and
neighbouring stars, taken at Ehrenbürg (
Franconia), 2001.
24.
Nymph
–
A nymph in Greek mythology and in Latin mythology is a minor female nature deity typically associated with a particular location or landform. They are beloved by many and dwell in mountainous regions and forests by lakes, charybdis and Scylla were once nymphs. Other nymphs, always in the shape of young maidens, were part of the retinue of a god, such as Dionysus, Hermes, or Pan, or a goddess, nymphs were the frequent target of satyrs. The Greek word νύμφη has bride and veiled among its meanings, other readers refer the word to a root expressing the idea of swelling. The mythologies of classicizing Roman poets were unlikely to have affected the rites and cult of individual nymphs venerated by people in the springs. Among the Roman literate class, their sphere of influence was restricted, the ancient Greek belief in nymphs survived in many parts of the country into the early years of the twentieth century, when they were usually known as nereids. At that time, John Cuthbert Lawson wrote and they might appear in a whirlwind. Such encounters could be dangerous, bringing dumbness, besotted infatuation, when parents believed their child to be nereid-struck, they would pray to Saint Artemidos. Due to widespread use of the term among lay persons and stereotypes attached, professionals nowadays prefer the term hypersexuality, the word nymphet is used to identify a sexually precocious girl. The term was made famous in the novel Lolita by Vladimir Nabokov, the main character, Humbert Humbert, uses the term many times, usually in reference to the title character. Thus the classes of nymphs tend to overlap, which complicates the task of precise classification, rose mentions dryads and hamadryads as nymphs of trees generally, meliai as nymphs of ash trees, and naiads as nymphs of water, but no others specifically. She is the consort of Acheron, and the mother of Ascalaphus, leuce, lover of Hades Minthe, lover of Hades, rival of Persephone Melinoe Orphic nymph, daughter of Persephone and Zeus disguised as Pluto. Her name is an epithet of Hecate. Nymphs in such groupings could belong to any of the mentioned above. For lists of Naiads, Oceanids, Dryades etc and this motif supposedly came from an Italian report of a Roman sculpture of a nymph at a fountain above the River Danube
Nymph
–
In this 1896 painting by
John William Waterhouse,
Hylas is abducted by the
Naiads, i.e. fresh water nymphs
Nymph
–
Nymph with morning glory flowers
Nymph
–
Nymphe by Gaston Bussière
Nymph
–
Cave of the Storm Nymphs by
Sir Edward John Poynter
25.
Callisto (mythology)
–
In Greek mythology, Callisto or Kallisto was a nymph, or the daughter of King Lycaon, based on conflicting accounts of the myth. Transformed into a bear and set among the stars, she was the bear-mother of the Arcadians, the fourth Galilean moon of Jupiter is named after Callisto. Artemis Kalliste was worshipped in Athens in a shrine which lay outside the Dipylon gate, W. S. Ferguson suggested that Artemis Soteira and Artemis Kalliste were joined in a common cult administered by a single priest. The bearlike character of Artemis herself was a feature of the Brauronia, the constellation Boötes, was explicitly identified in the Hesiodic Astronomia as Arcas, the Bear-warden, He is Arkas the son of Kallisto and Zeus, and he lived in the country about Lykaion. After Zeus had seduced Kallisto, Lykaon, pretending not to know of the matter, entertained Zeus, as Hesiod says, according to Julien dHuy, who used phylogenetic and statistical tools, the story could be a recent transformation of a Palaeolithic myth. As a follower of Artemis, Callisto, who Hesiod said was the daughter of Lycaon, king of Arcadia, took a vow to remain a virgin, but to have sex with her, Zeus disguised himself as Artemis herself, in order to lure her into his embrace. Callisto was then turned into a bear, as Hesiod had told it. but afterwards, upon this, the goddess was enraged and changed her into a beast. Thus she became a bear and gave birth to a son called Arcas, in every case, Zeus placed them both in the sky as the constellations Ursa Major, called Arktos, the Bear, by Greeks, and Ursa Minor. According to Ovid, it was Jupiter who took the form of Diana so that he might evade his wife Juno’s detection, forcing himself upon Callisto while she was separated from Diana and the other nymphs. Callistos subsequent pregnancy was discovered months later while she was bathing with Diana. Diana became enraged when she saw that Callisto was pregnant and expelled her from the group, Callisto later gave birth to Arcas. Juno then took the opportunity to avenge her wounded pride and transformed the nymph into a bear, sixteen years later Callisto, still a bear, encountered her son Arcas hunting in the forest. Just as Arcas was about to kill his own mother with his javelin, Jupiter averted the tragedy by placing mother and son amongst the stars as Ursa Major and Minor, respectively. Juno, enraged that her attempt at revenge had been frustrated, appealed to Oceanus that the two never meet his waters, thus providing a poetic explanation for their circumpolar positions. The stars of Ursa Major were all circumpolar in Athens of 400 BCE, in the television series Hercules, The Legendary Journeys and its spinoff Xena, Warrior Princess, Callisto is portrayed by Hudson Leick. In the video game Persona 2, Eternal Punishment, Callisto is the initial Persona of supporting character Ulala Serizawa. In the video game God of War, Ghost of Sparta Callisto is portrayed as the mother of protagonist Kratos, in the video game The Secret World Callisto is the nickname of a quest giving the Non-Playing Character, NPC, and the myth related to a puzzle/investigation quest. In music, the song Like Callisto to a Star in Heaven by American heavy metal band Trivium dramatically retells the myth of Callistos rape, pregnancy, poeticon astronomicon, II.1, the Great Bear
Callisto (mythology)
–
In
Jupiter and Callisto by
François Boucher,
Zeus /
Jupiter takes the form of
Artemis /
Diana (
Nelson-Atkins Museum of Art,
Kansas City)
Callisto (mythology)
–
Titian 's
Diana and Callisto (1559) portrays the moment when Callisto's pregnancy is discovered (
National Gallery of Scotland).
26.
Lycosura
–
Lycosura was a city of Arcadia said by Pausanias to be the oldest city in the world, though there is no evidence for its existence before the fourth century BCE. The dates of both the temple and the group have occasioned some dispute. Remains of a stoa, altars and other structures have also been found, the Sanctuary of Despoina at Lycosoura is located 9 km WSW of Megalopolis,6.9 km SSE of Mount Lykaion, and 160 km SW of Athens. Her real name could not be revealed to anyone except those initiated to her mysteries at Lycosura and he relates that Lycosura was founded by Lycaon the son of Pelasgus, and that it was the oldest city in the world. He notes that Cleitor, the grandson of Arcas, dwelled in Lycosura, in 368/7 BCE, when many cities in the region were unified into the city of Megalopolis through persuasion or force, the citizens of Lycosura, Trapezus, Lycaea, and Tricoloni refused to relocate. The citizens of Trapezus were massacred or driven into exile by the Arcadians, but the citizens of Lycosura were spared due to reverence for the Sanctuary of Despoina, many of the cities of the region were thus abandoned in favor of Megalopolis and their sanctuaries fell out of use. Pausanias states that the Sanctuary of Despoina was 40 stades from Megalopolis, in the 2nd century CE a statue of the emperor Hadrian was dedicated in the temple. Coins from Megalopolis of the Severan period in the early 3rd century appear to depict the cult statue group, despite its significance to the Arcadians and occasional notice from the wider Mediterranean world, the cult of Despoina appears to have remained tied to this one sanctuary at Lycosura. The site of Lycosura occupies a hill of 632 m in the wooded, the Sanctuary of Despoina is sited in a declivity on the north-eastern face of the hill occupied by the city. The temple and considerable remains of the statuary group were discovered in 1889 CE by the Greek Archaeological Society. Dating of the finds and structures thus remains problematic, although later excavations, traces of the temenos wall have been detected on the north and the east sides of the sanctuary, the southern and western limits of the sacred area are thus unknown. The Temple of Despoina is prostyle-hexastyle in plan and in the Doric order - i. e. it had six Doric columns across the front façade only. In plan, the stylobate of the temple measures 11.15 by 21.35 m and is divided between a pronaos and a cella, the six columns of the façade are in marble, as is the entablature. A curious feature of temple is the doorway in the south wall facing the theater-like area. Although uncommon, side doorways are known from other temples in Arkadia, i. e. Athena Alea at Tegea, and Apollo Epikourios at Bassai. Rather than extending as steps along the four sides of the temple, the architecture also deviates from the standard Doric schema in that its Doric frieze is 1. 5x the height of the architrave. At the rear of the cella is a massive, c, 1m high stone podium designed to hold the cult statuary group, in front of which is a mosaic decorating the floor. General consensus holds that the first construction of this dates to the 4th century BCE
Lycosura
–
View SE toward the Temple of Despoina at Lycosoura.
Lycosura
–
Area shaded purple approximates the sacred precinct.
27.
Cronus
–
In Greek mythology, Cronus, or Kronos, was the leader and youngest of the first generation of Titans, the divine descendants of Uranus, the sky, and Gaia, the earth. He overthrew his father and ruled during the mythological Golden Age, until he was overthrown by his own son Zeus, Cronus was usually depicted with a harpe, scythe or a sickle, which was the instrument he used to castrate and depose Uranus, his father. Cronus was also identified in antiquity with the Roman deity Saturn. In an ancient myth recorded by Hesiods Theogony, Cronus envied the power of his father, Gaia created a great stone sickle and gathered together Cronus and his brothers to persuade them to castrate Uranus. Only Cronus was willing to do the deed, so Gaia gave him the sickle, when Uranus met with Gaia, Cronus attacked him with the sickle, castrating him and casting his testicles into the sea. From the blood spilled out from Uranus and fell upon the earth, the Gigantes, Erinyes. The testicles produced a white foam from which the goddess Aphrodite emerged, for this, Uranus threatened vengeance and called his sons Titenes for overstepping their boundaries and daring to commit such an act. After dispatching Uranus, Cronus re-imprisoned the Hecatonchires, and the Cyclopes and he and his sister Rhea took the throne of the world as king and queen. The period in which Cronus ruled was called the Golden Age, as the people of the time had no need for laws or rules, everyone did the right thing, and immorality was absent. Cronus learned from Gaia and Uranus that he was destined to be overcome by his own sons, just as he had overthrown his father. As a result, although he sired the gods Demeter, Hestia, Hera, Hades and Poseidon by Rhea, he devoured them all as soon as they were born to prevent the prophecy. When the sixth child, Zeus, was born Rhea sought Gaia to devise a plan to them and to eventually get retribution on Cronus for his acts against his father. Rhea secretly gave birth to Zeus in Crete, and handed Cronus a stone wrapped in swaddling clothes, also known as the Omphalos Stone, Rhea kept Zeus hidden in a cave on Mount Ida, Crete. Still other versions of the say that Zeus was raised by his grandmother. In other versions of the tale, Metis gave Cronus an emetic to force him to disgorge the children, after freeing his siblings, Zeus released the Hecatonchires, and the Cyclopes who forged for him his thunderbolts, Poseidons trident and Hades helmet of darkness. In a vast war called the Titanomachy, Zeus and his brothers and sisters, with the help of the Hecatonchires, and Cyclopes, overthrew Cronus and the other Titans. Afterwards, many of the Titans were confined in Tartarus, however, Atlas, Epimetheus, Helios, Gaia bore the monster Typhon to claim revenge for the imprisoned Titans. Accounts of the fate of Cronus after the Titanomachy differ, in Homeric and other texts he is imprisoned with the other Titans in Tartarus
Cronus
–
Giorgio Vasari: The Mutilation of Uranus by Saturn (Cronus)
Cronus
–
Cronus
Cronus
–
Painting by
Peter Paul Rubens of Cronus devouring one of his children
Cronus
–
4th-century Temple of
Saturn in the
Roman Forum.
28.
Inuit
–
Inuit are a group of culturally similar indigenous peoples inhabiting the Arctic regions of Greenland, Canada and Alaska. Inuit is a noun, the singular is Inuk. The Inuit languages are part of the Eskimo-Aleut family, Inuit Sign Language is a critically endangered language isolate spoken in Nunavut. In the United States and Canada, the term Eskimo was commonly used to describe the Inuit and Alaskas Yupik, however, Inuit is not accepted as a term for the Yupik, and Eskimo is the only term that includes Yupik, Iñupiat and Inuit. However, aboriginal peoples in Canada and Greenlandic Inuit view Eskimo as pejorative, in Canada, sections 25 and 35 of the Constitution Act of 1982 classified the Inuit as a distinctive group of Aboriginal Canadians who are not included under either the First Nations or the Métis. These areas are known in Inuktitut as the Inuit Nunangat, in the United States, the Iñupiat live primarily on the Alaska North Slope and on Little Diomede Island. The Greenlandic Inuit are descendants of migrations from Canada. In the 21st century they are citizens of Denmark, although not of the European Union, Inuit are the descendants of what anthropologists call the Thule culture, who emerged from western Alaska around 1000 CE. They had split from the related Aleut group about 4,000 years ago and from northeastern Siberian migrants, possibly related to the Chukchi language group and they spread eastwards across the Arctic. They displaced the related Dorset culture, the last major Paleo-Eskimo culture, Inuit legends speak of the Tuniit as giants, people who were taller and stronger than the Inuit. Less frequently, the legends refer to the Dorset as dwarfs, researchers believe that the Dorset culture lacked the dogs, larger weapons and other technologies of the Inuit society, which gave the latter an advantage. By 1300, Inuit migrants had reached west Greenland, where they settled, faced with population pressures from the Thule and other surrounding groups, such as the Algonquian and Siouan to the south, the Tuniit gradually receded. They were thought to have become extinct as a people by about 1400 or 1500. But, in the mid-1950s, researcher Henry B. Collins determined that, based on the ruins found at Native Point, the Sadlermiut population survived up until winter 1902–03, when exposure to new infectious diseases brought by contact with Europeans led to their extinction as a people. In the early 21st century, mitochondrial DNA research has supported the theory of continuity between the Tuniit and the Sadlermiut peoples and it also provided evidence that a population displacement did not occur within the Aleutian Islands between the Dorset and Thule transition. In contrast to other Tuniit populations, the Aleut and Sadlermiut benefited from both geographical isolation and their ability to adopt certain Thule technologies, in Canada and Greenland, Inuit circulated almost exclusively north of the Arctic tree line, the effective southern border of Inuit society. The most southern officially recognized Inuit community in the world is Rigolet in Nunatsiavut, south of Nunatsiavut, the descendants of the southern Labrador Inuit in NunatuKavut continued their traditional transhumant semi-nomadic way of life until the mid-1900s. The Nunatukavummuit people usually moved among islands and bays on a seasonal basis and they did not establish stationary communities
Inuit
–
Traditional qamutik (sled),
Cape Dorset,
Nunavut
Inuit
–
Aboriginal peoples
in Canada
Inuit
–
Hudson's Bay Company Ships bartering with Inuit off the Upper Savage Islands,
Hudson Strait, 1819
Inuit
–
Inupiat in a kayak, Noatak, Alaska, c. 1929 (photo by
Edward S. Curtis)
29.
Zeta Ursae Minoris
–
Zeta Ursae Minoris is a star in the constellation Ursa Minor. It has the traditional name Akhfa al Farkadain, from the Arabic أخفى الفرقدين aḫfa al-farqadayn the dimmer of the two calves, as opposed to Anwar al Farkadain the brighter of the two calves. These names were applied to Pherkad and Kochab, respectively. Zeta Ursae Minoris is a stellar class A-type main sequence star with an apparent magnitude of +4.28. It is approximately 380 light years from Earth, despite its classification as a main sequence dwarf star, Zeta UMi is 3.4 times the mass of the sun and its luminosity is about 200 solar luminosities. At a surface temperature of 8,700 kelvins, this star is actually on the verge of becoming a giant star, Zeta UMi may also be a variable of the Delta Scuti type
Zeta Ursae Minoris
–
Location of ζ Ursae Minoris.
30.
Alpha Ursae Majoris
–
Alpha Ursae Majoris, also named Dubhe, is the second-brightest star in the constellation of Ursa Major. Alpha Ursae Majoris forms part of the Big Dipper, and is the northern of the pointers, Dubhe is about 123 light years from the Sun and is a giant star that has evolved away from the main sequence after consuming the hydrogen at its core. It is a binary with a main sequence companion α UMa B that has a stellar classification of F0V. The companion star orbits at a separation of about 23 astronomical units. There is another spectroscopic binary 8 arc minutes distant, a 7th magnitude pair showing an F8 spectral type and it is sometimes referred to as Alpha Ursae majoris C, but is separately catalogued as HD95638. α Ursae Majoris has been reported to vary in brightness by about a thousandth of a magnitude, ten radial oscillation modes have been detected, with periods between 6.4 hours and 6.4 days. Although it is part of the constellation of Ursa Major, it does not form part of the Ursa Major Moving Group of stars that have a motion through space. α Ursae Majoris is the stars Bayer designation and it bore the traditional names Dubhe and Ak. Dubhe derives from the Arabic for bear, dubb, from the phrase ظهر الدب الاكبر żahr ad-dubb al-akbar the back of the Greater Bear, the rarer Ak means The Eye. In 2016, the International Astronomical Union organized a Working Group on Star Names to catalog, the WGSNs first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included Dubhe for this star. The Hindus refer to the star as Kratu, one of the Seven Rishis, consequently, Alpha Ursae Majoris itself is known as 北斗一 Běi Dǒu yī, and 天樞 Tiān Shū. Dubhe is the star of the State of Utah. Dubhe was a ship in the United States Navy, the Danish National Home Guard Navy ship MHV806 is also named Dubhe
Alpha Ursae Majoris
–
Dubhe "A" and faint companion binaries
Alpha Ursae Majoris
31.
Beta Ursae Majoris
–
Beta Ursae Majoris, also named Merak, is a star in the northern circumpolar constellation of Ursa Major. The apparent visual magnitude of this star is +2.37, extending an imaginary straight line from this star through the nearby Alpha Ursae Majoris extends to Polaris, the north star. Based upon parallax measurements of star, it is located at a distance of 79.7 light-years from the Sun. The spectrum shows this to have a classification of A1 V. The effective temperature of the envelope is about 9,225 K. It is larger than the Sun, with about 2.7 times the mass and 2.84 times the Solar radius. If they were viewed from the distance, Beta Ursae Majoris would appear much brighter than the Sun. The dust has a mass of about 0. 27% the mass of the Earth. This group has an age of about million years. As the members of this group share an origin and motion through space. β Ursae Majoris is the stars Bayer designation and it bore the traditional name Merak derived from the Arabic المراق al-maraqq the loins. In 2016, the International Astronomical Union organized a Working Group on Star Names to catalog, the WGSNs first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included Merak for this star. The Hindus called the star Pulaha, one of the Seven Rishis, consequently, Beta Ursae Majoris itself is known as 北斗二 and 天璇. USS Merak and USS Merak, both of United States navy ship, in the original Star Trek series episode The Cloud Minders, the planet Merak II is said to be suffering from a botanical plague that can only be treated by the use of the mineral zenite. The video game Devil Survivor 2 features Merak, alongside the other stars of the Big Digger, as the Septentrione, Merak features on the 2nd day in Osaka, Japan. In the anime Saint Seiya, also known as Knights of the Zodiac, hagen is the name of the God Warrior representing the star Beta Merak
Beta Ursae Majoris
32.
International Astronomical Union
–
The International Astronomical Union is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy. Among other activities, it acts as the recognized authority for assigning designations to celestial bodies. The IAU is a member of the International Council for Science and its main objective is to promote and safeguard the science of astronomy in all its aspects through international cooperation. The IAU maintains friendly relations with organizations that include amateur astronomers in their membership, the IAU has its head office on the second floor of the Institut dAstrophysique de Paris in the 14th arrondissement of Paris. The IAU is also responsible for the system of astronomical telegrams which are produced and distributed on its behalf by the Central Bureau for Astronomical Telegrams, the Minor Planet Center also operates under the IAU, and is a clearinghouse for all non-planetary or non-moon bodies in the Solar System. The Working Group for Meteor Shower Nomenclature and the Meteor Data Center coordinate the nomenclature of meteor showers, the IAU was founded on July 28,1919, at the Constitutive Assembly of the International Research Council held in Brussels, Belgium. The 7 initial member states were Belgium, Canada, France, Great Britain, Greece, Japan, the first executive committee consisted of Benjamin Baillaud, Alfred Fowler, and four vice presidents, William Campbell, Frank Dyson, Georges Lecointe, and Annibale Riccò. Thirty-two Commissions were appointed at the Brussels meeting and focused on topics ranging from relativity to minor planets, the reports of these 32 Commissions formed the main substance of the first General Assembly, which took place in Rome, Italy, May 2–10,1922. By the end of the first General Assembly, ten nations had joined the Union. Although the Union was officially formed eight months after the end of World War I, the first 50 years of the Unions history are well documented. Subsequent history is recorded in the form of reminiscences of past IAU Presidents, twelve of the fourteen past General Secretaries in the period 1964-2006 contributed their recollections of the Unions history in IAU Information Bulletin No.100. Six past IAU Presidents in the period 1976–2003 also contributed their recollections in IAU Information Bulletin No.104, the IAU includes a total of 12,664 individual members who are professional astronomers from 96 countries worldwide. 83% of all members are male, while 17% are female, among them the unions current president. Membership also includes 79 national members, professional astronomical communities representing their countrys affiliation with the IAU, the sovereign body of the IAU is its General Assembly, which comprises all members. The Assembly determines IAU policy, approves the Statutes and By-Laws of the Union, the right to vote on matters brought before the Assembly varies according to the type of business under discussion. On budget matters, votes are weighted according to the subscription levels of the national members. A second category vote requires a turnout of at least two-thirds of national members in order to be valid, an absolute majority is sufficient for approval in any vote, except for Statute revision which requires a two-thirds majority. An equality of votes is resolved by the vote of the President of the Union, since 1922, the IAU General Assembly meets every three years, with the exception of the period between 1938 and 1948, due to World War II
International Astronomical Union
–
International Astronomical Union
33.
Equatorial coordinate system
–
The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects. The origin at the center of the Earth means the coordinates are geocentric, a right-handed convention means that coordinates are positive toward the north and toward the east in the fundamental plane. This description of the orientation of the frame is somewhat simplified. A slow motion of Earths axis, precession, causes a slow, continuous turning of the system westward about the poles of the ecliptic. Superimposed on this is a motion of the ecliptic. In order to fix the primary direction, these motions necessitate the specification of the equinox of a particular date, known as an epoch. The three most commonly used are, Mean equinox of an epoch is a fixed standard direction. Mean equinox of date is the intersection of the ecliptic of date with the mean equator, commonly used in planetary orbit calculation. True equinox of date is the intersection of the ecliptic of date with the true equator and this is the actual intersection of the two planes at any particular moment, with all motions accounted for. A position in the coordinate system is thus typically specified true equinox and equator of date, mean equinox and equator of J2000.0. Note that there is no mean ecliptic, as the ecliptic is not subject to small periodic oscillations, a stars spherical coordinates are often expressed as a pair, right ascension and declination, without a distance coordinate. The direction of distant objects is the same for all observers. Telescopes equipped with equatorial mounts and setting circles employ the equatorial coordinate system to find objects, setting circles in conjunction with a star chart or ephemeris allow the telescope to be easily pointed at known objects on the celestial sphere. The declination symbol δ, measures the distance of an object perpendicular to the celestial equator, positive to the north. For example, the celestial pole has a declination of +90°. The origin for declination is the equator, which is the projection of the Earths equator onto the celestial sphere. Declination is analogous to terrestrial latitude, the right ascension symbol α, measures the angular distance of an object eastward along the celestial equator from the vernal equinox to the hour circle passing through the object. The vernal equinox point is one of the two where the ecliptic intersects the celestial equator, there are = 15° in one hour of right ascension, 24h of right ascension around the entire celestial equator
Equatorial coordinate system
–
As seen from above the
Earth 's
north pole, a star's
local hour angle (LHA) for an observer near New York (red). Also depicted are the star's
right ascension and Greenwich hour angle (GHA), the
local mean sidereal time (LMST) and
Greenwich mean sidereal time (GMST). The symbol ʏ identifies the
vernal equinox direction.
34.
Theta
–
Theta is the eighth letter of the Greek alphabet, derived from the Phoenician letter Teth. In the system of Greek numerals it has a value of 9, in Ancient Greek, θ represented the aspirated voiceless dental plosive /t̪ʰ/, but in Modern Greek it represents the voiceless dental fricative /θ/. In its archaic form, θ was written as a cross within a circle, archaic crossed forms of theta are seen in the wheel letters of Linear A and Linear B. The cursive form ϑ was retained by Unicode as U+03D1 ϑ GREEK THETA SYMBOL, for the purpose of writing Greek text, the two can be font variants of a single character, but θ and ϑ are also used as distinct symbols in technical and mathematical contexts. In the Latin script used for the Gaulish language, theta developed into the tau gallicum, conventionally transliterated as Ð, the phonetic value of the tau gallicum is thought to have been. The early Cyrillic letter fita developed from θ and this letter existed in the Russian alphabet until the 1918 Russian orthography reform. In the International Phonetic Alphabet, represents the voiceless dental fricative and it does not represent the consonant in the, which is the voiced dental fricative. The lower-case letter θ is used as a symbol for, A plane angle in geometry, a Variable in trigonometry A special function of several complex variables. One of the Chebyshev functions in prime number theory, the score of a test taker in item response theory. Theta Type Replication, a type of bacterial DNA replication specific to circular chromosomes, threshold value of an artificial neuron. A Bayer designation letter applied to a star in a constellation, usually the star so labelled. The parameter frequently used in writing the likelihood function, the Watterson estimator for the population mutation rate in population genetics. Indicates a minimum optimum integration level determined by the intersection of GG, the GG-LL schedules are a tool used in analyzing the potential benefits of a country pegging their domestic currency to a foreign currency. The reserve ratio of banks in economic models, the ordinal collapsing function developed by Solomon Feferman The upper-case letter Θ is used as a symbol for, Quantity or temperature, by SI standard. An asymptotically tight bound in the analysis of algorithms, a certain ordinal number in set theory. Pentaquarks, exotic baryons in particle physics, a brain signal frequency ranging from 4–8 Hz. One of the known as Greeks in finance, representing time decay of options or the change in the intrinsic value of an option divided by the number of days until the option expires. A variable indicating temperature difference in heat transfer, according to Porphyry of Tyros, the Egyptians used an X within a circle as a symbol of the soul, having a value of nine, it was used as a symbol for Ennead
Theta
–
The alphabet on a
black figure vessel, with a point-and-circle theta.
Theta
–
The name ARAÐÐOVNA on a Gaulish tombstone.
Theta
–
θ (θάνατος, death) in a mosaic
35.
Jupiter
–
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, Jupiter and Saturn are gas giants, the other two giant planets, Uranus and Neptune are ice giants. Jupiter has been known to astronomers since antiquity, the Romans named it after their god Jupiter. Jupiter is primarily composed of hydrogen with a quarter of its mass being helium and it may also have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rotation, the planets shape is that of an oblate spheroid. The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence, a prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere, Jupiter has at least 67 moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. Ganymede, the largest of these, has a greater than that of the planet Mercury. Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. In late February 2007, Jupiter was visited by the New Horizons probe, the latest probe to visit the planet is Juno, which entered into orbit around Jupiter on July 4,2016. Future targets for exploration in the Jupiter system include the probable ice-covered liquid ocean of its moon Europa, Earth and its neighbor planets may have formed from fragments of planets after collisions with Jupiter destroyed those super-Earths near the Sun. Astronomers have discovered nearly 500 planetary systems with multiple planets, Jupiter moving out of the inner Solar System would have allowed the formation of inner planets, including Earth. Jupiter is composed primarily of gaseous and liquid matter and it is the largest of the four giant planets in the Solar System and hence its largest planet. It has a diameter of 142,984 km at its equator, the average density of Jupiter,1.326 g/cm3, is the second highest of the giant planets, but lower than those of the four terrestrial planets. Jupiters upper atmosphere is about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules, a helium atom has about four times as much mass as a hydrogen atom, so the composition changes when described as the proportion of mass contributed by different atoms. Thus, Jupiters atmosphere is approximately 75% hydrogen and 24% helium by mass, the atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, the outermost layer of the atmosphere contains crystals of frozen ammonia. The interior contains denser materials - by mass it is roughly 71% hydrogen, 24% helium, through infrared and ultraviolet measurements, trace amounts of benzene and other hydrocarbons have also been found
Jupiter
–
Jupiter in natural color, photographed by the
Cassini spacecraft in 2001
Jupiter
Jupiter
–
Jupiter's diameter is one
order of magnitude smaller (×0.10045) than the Sun, and one order of magnitude larger (×10.9733) than the Earth. The Great Red Spot is roughly the same size as the Earth.
Jupiter
–
This view of Jupiter's Great Red Spot and its surroundings was obtained by
Voyager 1 on February 25, 1979, when the spacecraft was 9.2 million km (5.7 million mi) from Jupiter. The white oval storm directly below the Great Red Spot is approximately the same diameter as Earth.
36.
Asteroseismology
–
Asteroseismology is the study of oscillations in stars. Asteroseismology is closely related to helioseismology, the study of stellar oscillations specifically in the Sun, though both are based on the same underlying physics, more and qualitatively different information is available for the Sun because its surface can be resolved. In non-rotating stars, modes with the same angular degree must all have the same frequency because there is no preferred axis. The angular degree indicates the number of lines on the stellar surface, so for large values of ℓ. As a consequence, modes can only be detected up to a degree of about 3 in intensity. The last two are defined by N2 = g and S ℓ2 = ℓ c s 2 r 2 respectively. By analogy with the behaviour of simple harmonic oscillators, this implies that oscillating solutions exist when the frequency is greater or less than both S ℓ and N. We identify the former case as high-frequency pressure modes and the latter as low-frequency gravity modes and this basic separation allows us to determine where we expect what kind of mode to resonate in a star. By plotting the curves ω = N and ω = S ℓ, κ -mechanism Under fairly specific conditions, some stars have regions where heat is transported by radiation and the opacity is a sharply decreasing function of temperature. This opacity bump can drive oscillations through the κ -mechanism, suppose that, at the beginning of an oscillation cycle, the stellar envelope has contracted. By expanding and cooling slightly, the layer in the opacity bump becomes more opaque, absorbs more radiation and this heating causes expansion, further cooling and the layer becomes even more opaque. This continues until the material opacity stops increasing so rapidly, at point the radiation trapped in the layer can escape. The star contracts and the cycle prepares to commence again, in this sense, the opacity acts like a valve that traps heat in the stars envelope. Pulsations driven by the κ -mechanism are coherent and have relatively large amplitudes and it drives the pulsations in many of the longest-known variable stars, including the Cepheid and RR Lyrae variables. In stars with surface convection zones, turbulent fluids motions near the surface simultaneously excite, because the modes are intrinsically stable, they have low amplitudes and are relatively short-lived. This is the mechanism in all solar-like oscillators. This mechanism is known as blocking and is believed to drive pulsations in the γ Doradus variables. Observations from the Kepler satellite revealed eccentric binary systems in which oscillations are excited during the closest approach and these systems are known as heartbeat stars because of the characteristic shape of the lightcurves
Asteroseismology
–
Different oscillation modes penetrate to different depths inside a star.
37.
Stellar classification
–
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with absorption lines, each line indicates an ion of a certain chemical element, with the line strength indicating the abundance of that ion. The relative abundance of the different ions varies with the temperature of the photosphere, the spectral class of a star is a short code summarizing the ionization state, giving an objective measure of the photospheres temperature and density. Most stars are classified under the Morgan–Keenan system using the letters O, B, A, F, G, K, and M. Each letter class is subdivided using a numeric digit with 0 being hottest and 9 being coolest. The sequence has been expanded with classes for other stars and star-like objects that do not fit in the system, such as class D for white dwarfs. In the MK system, a luminosity class is added to the class using Roman numerals. This is based on the width of absorption lines in the stars spectrum. The full spectral class for the Sun is then G2V, indicating a main-sequence star with a temperature around 5,800 K, the conventional color description takes into account only the peak of the stellar spectrum. This means that the assignment of colors of the spectrum can be misleading. There are no green, indigo, or violet stars, likewise, the brown dwarfs do not literally appear brown. The modern classification system is known as the Morgan–Keenan classification, each star is assigned a spectral class from the older Harvard spectral classification and a luminosity class using Roman numerals as explained below, forming the stars spectral type. The spectral classes O through M, as well as more specialized classes discussed later, are subdivided by Arabic numerals. For example, A0 denotes the hottest stars in the A class, fractional numbers are allowed, for example, the star Mu Normae is classified as O9.7. The Sun is classified as G2, the conventional color descriptions are traditional in astronomy, and represent colors relative to the mean color of an A-class star, which is considered to be white. The apparent color descriptions are what the observer would see if trying to describe the stars under a dark sky without aid to the eye, or with binoculars. However, most stars in the sky, except the brightest ones, red supergiants are cooler and redder than dwarfs of the same spectral type, and stars with particular spectral features such as carbon stars may be far redder than any black body. O-, B-, and A-type stars are called early type
Stellar classification
–
Secchi spectral types (152 Schjellerup is
Y Canum Venaticorum)
Stellar classification
–
Hertzsprung–Russell diagram
Stellar classification
–
Artist's impression of
Aludra, a B5 supergiant
Stellar classification
–
Fomalhaut, an A3 main-sequence star
38.
Red giant
–
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large, the appearance of the red giant is from yellow-orange to red, including the spectral types K and M, but also class S stars and most carbon stars. The most common red giants are stars on the red-giant branch that are still fusing hydrogen into helium in a shell surrounding an inert helium core. Red giants are stars that have exhausted the supply of hydrogen in their cores and have begun thermonuclear fusion of hydrogen in a shell surrounding the core and they have radii tens to hundreds of times larger than that of the Sun. However, their outer envelope is lower in temperature, giving them a reddish-orange hue, despite the lower energy density of their envelope, red giants are many times more luminous than the Sun because of their great size. Among the asymptotic-giant-branch stars belong the carbon stars of type C-N and late C-R, produced when carbon, the first dredge-up occurs during hydrogen shell burning on the red-giant branch, but does not produce a large carbon abundance at the surface. The second, and sometimes third, dredge up occurs during helium shell burning on the asymptotic-giant branch, the stellar limb of a red giant is not sharply-defined, contrary to their depiction in many illustrations. Rather, due to the low mass density of the envelope, such stars lack a well-defined photosphere. The coolest red giants have complex spectra, with lines, emission features. Red giants are evolved from main-sequence stars with masses in the range from about 0.3 M☉ to around 8 M☉, when a star initially forms from a collapsing molecular cloud in the interstellar medium, it contains primarily hydrogen and helium, with trace amounts of metals. These elements are all uniformly mixed throughout the star, the star reaches the main sequence when the core reaches a temperature high enough to begin fusing hydrogen and establishes hydrostatic equilibrium. Over its main sequence life, the star slowly converts the hydrogen in the core into helium, for the Sun, the main-sequence lifetime is approximately 10 billion years. More-massive stars burn disproportionately faster and so have a lifetime than less massive stars. When the star exhausts the hydrogen fuel in its core, nuclear reactions can no longer continue and this brings additional hydrogen into a zone where the temperature and pressure are adequate to cause fusion to resume in a shell around the core. The higher temperatures lead to increasing rates, enough to increase the stars luminosity by a factor of 1. The outer layers of the star then expand greatly, thus beginning the red-giant phase of the stars life, in actuality, though, the color usually is orange. At this time, the star is said to be ascending the red-giant branch of the Hertzsprung–Russell diagram, the outer layers carry the energy evolved from fusion to the surface by way of convection. This causes material exposed to nuclear burning in the interior to be brought to the stars surface for the first time in its history
Red giant
–
Mira, a red giant
Red giant
–
Hertzsprung–Russell diagram
Red giant
–
This image tracks the life of a
Sun -like star, from its
birth on the left side of the frame to its
evolution into a red giant on the right after billions of years.
Red giant
–
Mira A is an old star, already shedding its outer layers into space.
39.
Helium flash
–
A helium flash is a very brief thermal runaway nuclear fusion of large quantities of helium into carbon through the triple-alpha process in the core of low mass stars during their red giant phase. A much rarer runaway helium fusion process can occur on the surface of accreting white dwarf stars. Low mass stars do not produce enough pressure to initiate normal helium fusion. This increases the density and temperature of the core until it reaches approximately 100 million kelvin, in main sequence stars, thermal expansion regulates the core temperature, but in degenerate cores this does not occur. Helium fusion increases the temperature, which increases the fusion rate and this produces a flash of very intense helium fusion that lasts only a few minutes, but briefly emits energy at a rate comparable to the entire Milky Way galaxy. Thus the helium flash is mostly undetectable to observation, and is described solely by astrophysical models, after the cores expansion and cooling, the stars surface rapidly cools and contracts until it is roughly 2% of its former radius and luminosity. It is estimated that the helium core weighs about 40% of the star mass. During the red giant phase of evolution in stars with less than 2.0 M☉ the nuclear fusion of hydrogen ceases in the core as it is depleted. Thus the thermal pressure from fusion is no longer sufficient to counter the gravitational collapse and this causes the star to start contracting and increasing in temperature until it eventually becomes compressed enough for the helium core to become degenerate matter. The explosive nature of the helium flash arises from its place in degenerate matter. However, since degeneracy pressure is dominating thermal pressure, the pressure is only weakly dependent on temperature. Thus, the increase in temperature only causes a slight increase in pressure. The core can then expand and cool down and a burning of helium will continue. A star with mass greater than about 2.25 M☉ starts to burn helium without its core becoming degenerate, in a very low-mass star, the core is never hot enough to ignite helium. The degenerate helium core will keep on contracting, and finally becomes a white dwarf. The helium flash is not directly observable on the surface by electromagnetic radiation, the flash occurs in the core deep inside the star, and the net effect will be that all released energy is absorbed by the entire core, leaving the degenerate state to become nondegenerate. Earlier computations indicated that a mass loss would be possible in some cases. This hydrogen can build up to form a shell near the surface of the star, when the mass of hydrogen becomes sufficiently large, runaway fusion causes a nova
Helium flash
–
Small white
dwarf star undergoing a helium flash.
Helium flash
–
Fusion of helium in the core of low mass stars.
40.
R Coronae Borealis variable
–
An R Coronae Borealis variable is an eruptive variable star that varies in luminosity in two modes, one low amplitude pulsation, and one irregular unpredictably sudden fading by 1 to 9 magnitudes. The prototype star R Coronae Borealis was discovered by the English amateur astronomer Edward Pigott in 1795, since then, only about 100 RCB variables have been identified, making this class a very rare kind of star. The fading is caused by condensation of carbon to soot, making the star fade in visible light while measurements in infrared light exhibit no real luminosity decrease. R Coronae Borealis variables are typically supergiant stars in the spectral classes F and G, with typical C2 and CN molecular bands, there is a considerable variation in spectrum between various RCB specimens. Most of the stars with known spectrum are either F to G class supergiants, three of the stars are however of the blue B type, for example VZ Sagittarii. Four stars are unusually and inexplicably poor in iron absorption lines in the spectrum, the constant features are prominent Carbon lines, strong atmospheric Hydrogen deficiencies, and obviously the intermittent fadings. The DY Persei variables have been considered a sub-class of R CrB variable, although they are less luminous carbon-rich AGB stars, the 20 radii model requires a large and thereby long-time buildup of the obstructing dust cloud, making the fast light decline hard to comprehend. The formation of the stars themselves is also unclear, standard stellar evolution models do not produce large luminous stars with essentially zero hydrogen. The two main theories to explain these stars are both somewhat exotic, perhaps befitting such rare stars, in one, a merger occurs between two white dwarf stars, one a Helium white dwarf and the other a carbon-oxygen white dwarf. White dwarfs are naturally lacking in hydrogen and the resultant star would also lack that element and it is possible that the diversity of R CrB stars is caused by a diversity of formation mechanisms, relating them to extreme helium stars and hydrogen-deficient carbon stars. This list contains all the R CrB stars listed in the GCVS, DY Persei is not included although it may be a related type of variable. Clayton, from SAO/NASA Astrophysics Data System Variable Star of the Month, January,2000, R Coronae Borealis, at the AAVSO website
R Coronae Borealis variable
–
An
AAVSO light curve of fadings by
R Coronae Borealis, the prototype star
41.
Astrophysical X-ray source
–
Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays. Some solar system bodies emit X-rays, the most notable being the Moon, a combination of many unresolved X-ray sources is thought to produce the observed X-ray background. Furthermore, celestial entities in space are discussed as celestial X-ray sources, the origin of all observed astronomical X-ray sources is in, near to, or associated with a coronal cloud or gas at coronal cloud temperatures for however long or brief a period. Clusters of galaxies are formed by the merger of smaller units of matter, the infalling material gains kinetic energy as it falls into the clusters gravitational potential well. The infalling gas collides with gas already in the cluster and is heated to between 107 and 108 K depending on the size of the cluster. This very hot gas emits X-rays by thermal emission. The galaxies and dark matter are collisionless and quickly become virialised, a quasi-stellar radio source is a very energetic and distant galaxy with an active galactic nucleus. QSO 0836+7107 is a Quasi-Stellar Object that emits baffling amounts of radio energy and this radio emission is caused by electrons spiraling along magnetic fields producing cyclotron or synchrotron radiation. These electrons can interact with visible light emitted by the disk around the AGN or the black hole at its center. These photons accelerate the electrons, which then emit X- and gamma-radiation via Compton, on board the Compton Gamma Ray Observatory is the Burst and Transient Source Experiment which detects in the 20 keV to 8 MeV range. QSO 0836+7107 or 4C71.07 was detected by BATSE as a source of gamma rays. What BATSE has discovered is that it can be a soft gamma-ray source, QSO 0836+7107 is the faintest and most distant object to be observed in soft gamma rays. It has already observed in gamma rays by the Energetic Gamma Ray Experiment Telescope also aboard the Compton Gamma Ray Observatory. Seyfert galaxies are a class of galaxies with nuclei that produce spectral line emission from highly ionized gas and they are a subclass of active galactic nuclei, and are thought to contain supermassive black holes. The following early-type galaxies have been observed to be X-ray bright due to hot gaseous coronae,315,1316,1332,1395,2563,4374,4382,4406,4472,4594,4636,4649, and 5128. The X-ray emission can be explained as thermal bremsstrahlung from hot gas, ultraluminous X-ray sources are pointlike, nonnuclear X-ray sources with luminosities above the Eddington limit of 3 ×1032 W for a 20 M☉ black hole. Many ULXs show strong variability and may be black hole binaries, to fall into the class of intermediate-mass black holes, their luminosities, thermal disk emissions, variation timescales, and surrounding emission-line nebulae must suggest this. However, when the emission is beamed or exceeds the Eddington limit, the nearby spiral galaxy NGC1313 has two compact ULXs, X-1 and X-2
Astrophysical X-ray source
–
X-rays start at ~0.008 nm and extend across the electromagnetic spectrum to ~8 nm, over which Earth's atmosphere is
opaque.
Astrophysical X-ray source
–
X-ray photo by Chandra X-ray Observatory of the
Bullet Cluster. Exposure time was 140 hours. The scale is shown in mega
parsecs.
Redshift (z) = 0.3, meaning its light has wavelengths stretched by a factor of 1.3.
Astrophysical X-ray source
–
A view of 4C 71.07 from observations by the Burst and Transient Source Experiment. This helped convince scientists that they were studying data from the quasar and not some other source in the neighborhood.
Astrophysical X-ray source
–
Chandra image of
Cygnus X-1, which was the first strong black hole candidate to be discovered.
42.
ROSAT
–
ROSAT was a German Aerospace Center-led satellite X-ray telescope, with instruments built by West Germany, the United Kingdom and the United States. It was launched on 1 June 1990, on a Delta II rocket from Cape Canaveral, on what was designed as an 18-month mission. ROSAT actually operated for eight years, finally shutting down on 12 February 1999. Parts as heavy as 400 kg could impact the surface intact, ROSAT eventually re-entered the Earths atmosphere on 23 October 2011. According to NASA, the Roentgensatellit was a joint German, U. S. ROSAT carried a German-built imaging X-ray Telescope with three focal plane instruments, two German Position Sensitive Proportional Counters and the US-supplied High Resolution Imager. The X-ray mirror assembly was a grazing incidence four-fold nested Wolter I telescope with an 84-cm diameter aperture, the angular resolution was less than 5 arcsecond at half energy width. The XRT assembly was sensitive to X-rays between 0.1 and 2 keV, in addition, a British-supplied extreme ultraviolet telescope, the Wide Field Camera, was coaligned with the XRT and covered the energy band from 0.042 to 0.21 keV. ROSATs unique strengths were high resolution, low-background, soft X-ray imaging for the study of the structure of low surface brightness features. ROSAT was capable of fast slews which makes it possible to observe two targets on opposite hemispheres during each orbit, the pointing accuracy was 1 arcminute with stability less than 5 arcsec per sec and jitter radius of ~10 arcsec. Two CCD star sensors were used for position sensing of guide stars. The post facto attitude determination accuracy was 6 arcsec, the survey was carried out in the scan mode. The second phase consists of the remainder of the mission and was devoted to pointed observations of selected astrophysical sources, in ROSATs pointed phase, observing time was allocated to Guest Investigators from all three participating countries through peer review of submitted proposals. ROSAT had a life of 18 months, but was expected to operate beyond its nominal lifetime. The main assembly was a German-built imaging X-ray Telescope with three focal plane instruments, two German Position Sensitive Proportional Counters and the US-supplied High Resolution Imager. The X-ray mirror assembly was a grazing incidence four-fold nested Wolter I telescope with an 84 cm diameter aperture and 240 cm focal length, the angular resolution was less than 5 arcsec at half energy width. The XRT assembly was sensitive to X-rays between 0.1 and 2 keV, each Position Sensitive Proportional Counter is a thin-window gas counter. Each incoming X-ray photon produces an electron cloud whose position and charge are detected using two wire grids, the photon position is determined with an accuracy of about 120 micrometers. The electron clouds charge corresponds to the photon energy, the US supplied High Resolution Imager used a crossed grid detector with a position accuracy to 25 micrometers
ROSAT
–
Launch of the ROSAT in
Cape Canaveral,
Florida.
ROSAT
–
ROSAT: one of the last images of ROSAT before reentry
43.
Neutron star
–
A neutron star is the collapsed core of a large star. Neutron stars are the smallest and densest stars known to exist, though neutron stars typically have a radius on the order of 10 km, they can have masses of about twice that of the Sun. They result from the explosion of a massive star, combined with gravitational collapse. They are supported against further collapse by neutron degeneracy pressure, a described by the Pauli exclusion principle. If the remnant has too great a density, something which occurs in excess of a limit of the size of neutron stars at 2–3 solar masses. Neutron stars that can be observed are very hot and typically have a temperature around 6×105 K. They are so dense that a normal-sized matchbox containing neutron-star material would have a mass of approximately 3 billion tonnes and their magnetic fields are between 108 and 1015 times as strong as that of the Earth. The gravitational field at the stars surface is about 2×1011 times that of the Earth. As the stars core collapses, its rotation rate increases as a result of conservation of angular momentum, some neutron stars emit beams of electromagnetic radiation that make them detectable as pulsars. Indeed, the discovery of pulsars in 1967 was the first observational suggestion that stars exist. The radiation from pulsars is thought to be emitted from regions near their magnetic poles. The fastest-spinning neutron star known is PSR J1748-2446ad, rotating at a rate of 716 times a second or 43,000 revolutions per minute, giving a linear speed at the surface on the order of 0.24 c. There are thought to be around 100 million neutron stars in the Milky Way, however, most are old and cold, and neutron stars can only be easily detected in certain instances, such as if they are a pulsar or part of a binary system. Soft gamma repeaters are conjectured to be a type of neutron star with strong magnetic fields, known as magnetars, or alternatively. Additionally, such accretion can recycle old pulsars and potentially cause them to mass and spin-up to very fast rotation rates. The merger of binary stars may be the source of short-duration gamma-ray bursts and are likely strong sources of gravitational waves. Any main-sequence star with a mass of above 8 times the mass of the sun has the potential to produce a neutron star. As the star evolves away from the sequence, subsequent nuclear burning produces an iron-rich core
Neutron star
–
Radiation from the
pulsar PSR B1509-58, a rapidly spinning neutron star, makes nearby gas glow in
X-rays (gold, from
Chandra) and illuminates the rest of the
nebula, here seen in
infrared (blue and red, from
WISE).
Neutron star
–
The first direct observation of a neutron star in visible light. The neutron star is
RX J185635-3754.
Neutron star
–
NASA artist's conception of a "
starquake ", or "stellar quake".
Neutron star
–
Circinus X-1: X-ray light rings from a binary neutron star (24 June 2015;
Chandra X-ray Observatory).
44.
Lowell Observatory
–
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, in 2011, the Observatory was named one of The Worlds 100 Most Important Places by TIME. It was at the Lowell Observatory that the dwarf planet Pluto was discovered in 1930 by Clyde Tombaugh, the Observatorys original 61-centimeter Alvan Clark & Sons Telescope is still in use today for public education. It was founded by astronomer Percival Lowell of Bostons well-known Lowell family and is overseen by a sole trustee, the first trustee was Lowells third cousin Guy Lowell. Percivals nephew Roger Putnam served from 1927–1967, followed by Rogers son Michael, Michaels brother William Lowell Putnam III, the observatory operates several telescopes at three locations in the Flagstaff area. The telescope, built in 1896 for $20,000, was assembled in Boston by Alvan Clark & Sons, also located on the Mars Hill campus is the 33-centimeter Pluto Discovery Telescope, used by Clyde Tombaugh in 1930 to discover the dwarf planet Pluto. Lowell is a partner with the United States Naval Observatory and Naval Research Laboratory in the Navy Precision Optical Interferometer also located at that site, the Observatory also operates smaller research telescopes at its historic site on Mars Hill and in Australia and Chile. Past Anderson Mesa, on the peak of Happy Jack, Lowell Observatory has also built and is commissioning the 4. 28-meter Discovery Channel Telescope in partnership with Discovery Communications, Inc. Aside from the array of research and discoveries listed below. When Harold L. Johnson took over as the director in 1952, in 1953, the current 53 cm telescope was erected. Beginning in 1954, this telescope began monitoring the brightness of two planets, and comparing these measurements with a reference set of sunlike stars. Lowell Observatory is building a major new reflecting telescope in partnership with Discovery Communications, located near Happy Jack, the primary mirror of the Discovery Channel Telescope will be 4.28 m in diameter. It will be notable for its uncommon meniscus design for such a large mirror. This mirror was ground and polished into its parabolic shape at the Optical Fabrication, Lowell Observatorys astronomers conduct research on a wide range of solar system and astrophysical topics using ground-based, airborne, and space-based telescopes. In addition, the Observatory staff designs and builds custom instrumentation for use on Lowells telescopes, for example, Lowell staff built a sophisticated high-speed camera for use on the Stratospheric Observatory for Infrared Astronomy. SOFIA is a joint project of the United States and German space agencies, Lowell, Percival, Pickering, W. H. and the founding of the Lowell Observatory. National Historic Landmarks Program, Lowell Observatory+ Historic American Buildings Survey No, aZ-206, Lowell Observatory,1400 West Mars Hill Road, Flagstaff, Coconino County, AZ HABS No. AZ-206-A, Lowell Observatory, Slipher Building HABS No, aZ-206-B, Lowell Observatory, Clark Dome HABS No
Lowell Observatory
–
The
Clark Telescope Dome on Mars Hill
Lowell Observatory
–
Discovery Channel Telescope
Lowell Observatory
–
Percival Lowell in the observer's chair of the Alvan Clark 61 cm (24-inch) refractor
Lowell Observatory
–
Alvan Clark refractor telescope, the first permanent telescope at Lowell Observatory
45.
Hubble Space Telescope
–
The Hubble Space Telescope is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. Although not the first space telescope, Hubble is one of the largest and most versatile, with a 2. 4-meter mirror, Hubbles four main instruments observe in the near ultraviolet, visible, and near infrared spectra. Hubbles orbit outside the distortion of Earths atmosphere allows it to take extremely high-resolution images, Hubble has recorded some of the most detailed visible light images ever, allowing a deep view into space and time. Many Hubble observations have led to breakthroughs in astrophysics, such as determining the rate of expansion of the universe. The HST was built by the United States space agency NASA, the Space Telescope Science Institute selects Hubbles targets and processes the resulting data, while the Goddard Space Flight Center controls the spacecraft. Space telescopes were proposed as early as 1923, Hubble was funded in the 1970s, with a proposed launch in 1983, but the project was beset by technical delays, budget problems, and the Challenger disaster. When finally launched in 1990, Hubbles main mirror was found to have been ground incorrectly, the optics were corrected to their intended quality by a servicing mission in 1993. Hubble is the telescope designed to be serviced in space by astronauts. After launch by Space Shuttle Discovery in 1990, five subsequent Space Shuttle missions repaired, upgraded, the fifth mission was canceled on safety grounds following the Columbia disaster. However, after spirited public discussion, NASA administrator Mike Griffin approved the fifth servicing mission, the telescope is operating as of 2017, and could last until 2030–2040. Its scientific successor, the James Webb Space Telescope, is scheduled for launch in 2018, the history of the Hubble Space Telescope can be traced back as far as 1946, to the astronomer Lyman Spitzers paper Astronomical advantages of an extraterrestrial observatory. In it, he discussed the two advantages that a space-based observatory would have over ground-based telescopes. First, the resolution would be limited only by diffraction, rather than by the turbulence in the atmosphere. Second, a telescope could observe infrared and ultraviolet light. Spitzer devoted much of his career to pushing for the development of a space telescope, space-based astronomy had begun on a very small scale following World War II, as scientists made use of developments that had taken place in rocket technology. An orbiting solar telescope was launched in 1962 by the United Kingdom as part of the Ariel space program, oAO-1s battery failed after three days, terminating the mission. It was followed by OAO-2, which carried out observations of stars and galaxies from its launch in 1968 until 1972. The continuing success of the OAO program encouraged increasingly strong consensus within the community that the LST should be a major goal
Hubble Space Telescope
–
The Hubble Space Telescope as seen from the departing
Space Shuttle Atlantis, flying Servicing Mission 4 (
STS-125), the fifth and final human spaceflight to it.
Hubble Space Telescope
–
Grinding of Hubble's primary mirror at Perkin-Elmer, March 1979
Hubble Space Telescope
–
The backup mirror, by Kodak; its inner support structure can be seen because it is not coated with a reflective surface.
Hubble Space Telescope
–
The OTA, metering truss, and secondary baffle are visible in this image of Hubble during early construction.
46.
Star formation
–
Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as stellar nurseries or star-forming regions, fuse to form stars. It is closely related to formation, another branch of astronomy. Star formation theory, as well as accounting for the formation of a star, must also account for the statistics of binary stars. In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z =6.60, a spiral galaxy like the Milky Way contains stars, stellar remnants, and a diffuse interstellar medium of gas and dust. The interstellar medium consists of 10−4 to 106 particles per cm3 and is composed of roughly 70% hydrogen by mass. This medium has been enriched by trace amounts of heavier elements that were ejected from stars as they passed beyond the end of their main sequence lifetime. Higher density regions of the interstellar medium form clouds, or diffuse nebulae, in the dense nebulae where stars are produced, much of the hydrogen is in the molecular form, so these nebulae are called molecular clouds. These giant molecular clouds have densities of 100 particles per cm3, diameters of 100 light-years, masses of up to 6 million solar masses. About half the mass of the galactic ISM is found in molecular clouds and in the Milky Way there are an estimated 6,000 molecular clouds. The nearest nebula to the Sun where massive stars are being formed is the Orion nebula,1,300 ly away, however, lower mass star formation is occurring about 400–450 light years distant in the ρ Ophiuchi cloud complex. A more compact site of formation is the opaque clouds of dense gas and dust known as Bok globules. These can form in association with collapsing molecular clouds or possibly independently, the Bok globules are typically up to a light year across and contain a few solar masses. They can be observed as dark clouds silhouetted against bright emission nebulae or background stars, over half the known Bok globules have been found to contain newly forming stars. An interstellar cloud of gas will remain in equilibrium as long as the kinetic energy of the gas pressure is in balance with the potential energy of the internal gravitational force. Mathematically this is expressed using the theorem, which states that, to maintain equilibrium. If a cloud is massive enough that the gas pressure is insufficient to support it, the mass above which a cloud will undergo such collapse is called the Jeans mass. The Jeans mass depends on the temperature and density of the cloud and this coincides with the typical mass of an open cluster of stars, which is the end product of a collapsing cloud. In triggered star formation, one of several events occur to compress a molecular cloud
Star formation
–
Star formation
Star formation
–
Hubble telescope image known as
Pillars of Creation, where stars are forming in the
Eagle Nebula.
Star formation
–
Assembly of galaxy in early Universe.
Star formation
–
Stellar cluster and
star-forming region M 17.
47.
NGC 6217
–
NGC6217 is a barred spiral galaxy located some 67 million light years away, in the constellation Ursa Minor. It can be located with a 10 cm or larger telescope as an 11th magnitude object about 2. 5° east-northeast of the star Zeta Ursae Minoris, the galaxy is inclined by an angle of 33° to the line of sight along a position angle of 162°. The nucleus is spherical in shape, showing no indication of oblateness, the prominent bar spans an angular distance of 48″ across the galaxy along a position angle of 35. 97° ±0. 35°. At 10″ southeast of the nucleus is a prominent region of star formation, the inner ring is about 43″.5 across. NGC6217 has been characterized as a starburst galaxy, which means it is undergoing a high rate of formation compared to a typical galaxy. As a result, the spectrum is dominated by stellar photoionization from young and this component is less than 10 million years old, producing a blue-hued spectral continuum with absorption weak lines from elements other than hydrogen and helium. At the core of the galaxy is a low-luminosity active galactic nucleus which has formed an H II region
NGC 6217
–
NGC 6217 photographed by the
Hubble Space Telescope
48.
Starburst galaxy
–
As such, the starburst nature of a galaxy is a phase, and one that typically occupies a brief period of a galaxys evolution. The majority of starburst galaxies are in the midst of a merger or close encounter with another galaxy, Starburst galaxies include M82, NGC 4038/NGC4039, and IC10. Starburst galaxies are defined by three interrelated factors, The rate at which the galaxy is currently converting gas into stars. The available quantity of gas from which stars can be formed, a comparison of the timescale on which star formation will consume the available gas with the age or rotation period of the galaxy. Commonly used definitions include, Continued star-formation where the current SFR would exhaust the available gas reservoir in much less than the age of the Universe, Continued star-formation where the current SFR would exhaust the available gas reservoir in much less than the dynamical timescale of the galaxy. The current SFR, normalised by the past-averaged SFR, is greater than unity. This ratio is referred to as the birthrate parameter, Starburst galaxies feature a large amount of cool molecular gas in a small volume. Galaxies in the midst of a starburst also frequently show tidal tails, classifying types of starburst galaxies is difficult since starburst galaxies do not represent a specific type in and of themselves. Starbursts can occur in disk galaxies, and irregular galaxies often exhibit knots of starburst spread throughout the irregular galaxy, nevertheless, astronomers typically classify starburst galaxies based on their most distinct observational characteristics. Some of the include, Blue compact galaxies. These galaxies are often low mass, low metallicity, dust-free objects, because they are dust-free and contain a large number of hot, young stars, they are often blue in optical and ultraviolet colours. It was initially thought that BCGs were genuinely young galaxies in the process of forming their first generation of stars, however, old stellar populations have been found in most BCGs, and it is thought that efficient mixing may explain the apparent lack of dust and metals. Most BCGs show signs of recent mergers and/or close interactions, well-studied BCGs include IZw18, ESO338-IG04 and Haro11. Blue compact dwarf galaxies are small compact galaxies, green Pea galaxies are small compact galaxies resembling primordial starbursts. They were found by citizen scientists taking part in the Galaxy Zoo project and these galaxies are generally extremely dusty objects. The ultraviolet radiation produced by the obscured star-formation is absorbed by the dust and this explains the extreme red colours associated with ULIRGs. It is not known for sure that the UV radiation is produced purely by star-formation, Wolf-Rayet galaxies, galaxies where a large portion of the bright stars are Wolf-Rayet stars. The Wolf-Rayet phases is a relatively short-lived phase in the life of stars, typically 10% of the total life-time of these stars
Starburst galaxy
–
The
Antennae Galaxies are an example of a starburst galaxy occurring from the collision of NGC 4038/NGC 4039. Credit:
NASA /
ESA.
Starburst galaxy
–
Light and dust in a nearby starburst galaxy
Starburst galaxy
–
Artist's impression of a galaxy undergoing a starburst.
Starburst galaxy
–
Messier 82 is the prototype nearby starburst galaxy about 12 million light-years away in the constellation
Ursa Major.
49.
NGC 6251
–
NGC6251 is an active supergiant elliptical radio galaxy in the constellation Ursa Minor, and is more than 340 million light-years away from Earth. The galaxy has a Seyfert 2 active galactic nucleus, and is one of the most extreme examples of a Seyfert galaxy and this galaxy may be associated with gamma-ray source 3EG J1621+8203, which has high-energy gamma-ray emission. It is also noted for its one-sided radio jet—one of the brightest known—discovered in 1977, www. jb. man. ac. uk/atlas/ Wikisky image of NGC6251 Hubble Finds a Bare Black Hole Pouring Out Light
NGC 6251
–
Hubble image of the heart of the
active galaxy NGC 6251
50.
Radio galaxy
–
Radio galaxies and their relatives, radio-loud quasars and blazars, are types of active galaxy that are very luminous at radio wavelengths, with luminosities up to 1039 W between 10 MHz and 100 GHz. The radio emission is due to the synchrotron process, the observed structure in radio emission is determined by the interaction between twin jets and the external medium, modified by the effects of relativistic beaming. The host galaxies are almost exclusively large elliptical galaxies, radio-loud active galaxies can be detected at large distances, making them valuable tools for observational cosmology. Recently, much work has been done on the effects of objects on the intergalactic medium, particularly in galaxy groups. The radio emission from radio-loud active galaxies is synchrotron emission, as inferred from its smooth, broad-band nature. This implies that the plasma contains, at least, electrons with relativistic speeds. Since the plasma must be neutral, it must also contain either protons or positrons, there is no way of determining the particle content directly from observations of synchrotron radiation. A sister process to the radiation is the inverse-Compton process, in which the relativistic electrons interact with ambient photons. This has been used to argue that many sources are actually quite near the minimum-energy condition. In the latter case the electrons must have energies in excess of 1 TeV in typical magnetic field strengths. Again, polarization and continuum spectrum are used to distinguish the synchrotron radiation from other emission processes, jets and hotspots are the usual sources of high-frequency synchrotron emission. It is hard to distinguish observationally between the synchrotron and inverse-Compton radiation, making them a subject of ongoing research, processes, collectively known as particle acceleration, produce populations of relativistic and non-thermal particles that give rise to synchrotron and inverse-Compton radiation. Fermi acceleration is one plausible particle acceleration process in radio-loud active galaxies, radio galaxies, and to a lesser extent, radio-loud quasars display a wide range of structures in radio maps. The most common structures are called lobes, these are double, often fairly symmetrical. A significant minority of low-luminosity sources exhibit structures usually known as plumes which are more elongated. Some radio galaxies show one or two long narrow features known as coming directly from the nucleus and going to the lobes. Since the 1970s, the most widely accepted model has been that the lobes or plumes are powered by beams of high-energy particles and magnetic field coming from close to the active nucleus. The jets are believed to be the manifestations of the beams
Radio galaxy
51.
Active galactic nucleus
–
Such excess non-stellar emission has been observed in the radio, microwaves, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an active galaxy, the radiation from an AGN is believed to be a result of accretion of matter by a supermassive black hole at the center of its host galaxy. Numerous subclasses of AGN have been defined based on their observed characteristics, early photographic observations of nearby galaxies detected some characteristic signatures of AGN emission, although there was not yet a physical understanding of the nature of the AGN phenomenon. Further spectroscopic studies by astronomers including Vesto Slipher, Milton Humason, in 1943, Carl Seyfert published a paper in which he described observations of nearby galaxies having bright nuclei that were sources of unusually broad emission lines. Galaxies observed as part of study included NGC1068, NGC4151, NGC3516. Active galaxies such as these are known as Seyfert galaxies in honor of Seyferts pioneering work, the development of radio astronomy was a major catalyst to understanding AGN. Some of the earliest detected radio sources are nearby active elliptical galaxies such as Messier 87, the 3C radio survey led to further progress in discovery of new radio sources as well as identifying the visible-light sources associated with the radio emission. In photographic images, some of these objects were nearly point-like or quasi-stellar in appearance, a major breakthrough was the measurement of the redshift of the quasar 3C273 by Maarten Schmidt, published in 1963. Shortly afterward, optical spectra were used to measured the redshifts of a number of quasars including 3C48. The enormous luminosities of these quasars as well as their unusual spectral properties indicated that their power source could not be ordinary stars, Accretion of gas onto a supermassive black hole was suggested as the source of quasars power in papers by Edwin Salpeter and Yakov ZelDovich in 1964. Today, AGN are a topic of astrophysical research, both observational and theoretical. For a long time it has argued that an AGN must be powered by accretion of mass onto massive black holes. AGN are both compact and persistently extremely luminous, thus AGN-like characteristics are expected whenever a supply of material for accretion comes within the sphere of influence of the central black hole. In the standard model of AGN, cold material close to a black hole forms an accretion disc, dissipative processes in the accretion disc transport matter inwards and angular momentum outwards, while causing the accretion disc to heat up. The radiation from the accretion disc excites cold atomic material close to the black hole, a large fraction of the AGNs radiation may be obscured by interstellar gas and dust close to the accretion disc, but this will be re-radiated at some other waveband, most likely the infrared. Some accretion discs produce jets of twin, highly collimated, the direction of the jet ejection is determined either by the angular momentum axis of the accretion disc or the spin axis of the black hole. The jet production mechanism and indeed the jet composition on very small scales are not understood at present due to the resolution of astronomical instruments being too low, there exists a class of radiatively inefficient solutions to the equations that govern accretion. The most widely known of these is the Advection Dominated Accretion Flow, radiatively inefficient AGN would be expected to lack many of the characteristic features of standard AGN with an accretion disc
Active galactic nucleus
–
Image taken by the
Hubble Space Telescope of a 5000
light-year long jet ejected from the active
galaxy M87. The blue
synchrotron radiation contrasts with the yellow starlight from the host galaxy.
Active galactic nucleus
–
Unification by viewing angle. From bottom to top: down the jet -
Blazar, at an angle to the jet -
Quasar /
Seyfert 1 Galaxy, at 90 degrees from the jet -
Radio galaxy /
Seyfert 2 Galaxy
52.
Seyfert galaxy
–
Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars. They have quasar-like nuclei with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines and these galaxies have supermassive black holes at their centers which are surrounded by accretion discs of in-falling material. The accretion discs are believed to be the source of the ultraviolet radiation. Ultraviolet emission and absorption lines provide the best diagnostics for the composition of the surrounding material, Seyfert galaxies are named after Carl Seyfert, who first described this class in 1943. They noticed that NGC1068 showed six bright emission lines, which was considered unusual as most objects observed showed a spectrum corresponding to stars. In 1926, Edwin Hubble looked at the lines of NGC1068. In 1943, Carl Keenan Seyfert discovered more galaxies similar to NGC1068, in 1944 Cygnus A was detected at 160 MHz, and detection was confirmed in 1948 when it was established that it was a discrete source. Its double radio structure became apparent with the use of interferometry, in the next few years, other radio sources such as supernova remnants were discovered. In the 1960-1970s, research to understand the properties of Seyfert galaxies was carried out. Controversy existed over whether Seyfert redshifts were of cosmological origin, in the same time period, research had been undertaken to survey, identify and catalogue galaxies, including Seyferts. At the time, it was believed that 1% of spiral galaxies are Seyferts, by 1977, it was found that very few Seyfert galaxies are ellipticals, most of them being normal or barred spiral galaxies. During the same period, efforts have been made to gather spectrophotometric data for Seyfert galaxies. It became obvious that not all spectra from Seyfert galaxies look the same, a simple division into types I and II has been devised, with the classes depending on the relative width of their emission lines. It has been noticed that some Seyfert nuclei show intermediate properties. Early surveys for Seyfert galaxies were biased in counting only the brightest representatives of this group, Seyfert galaxies form a substantial fraction of the galaxies appearing in the Markarian catalog, a list of galaxies displaying an ultraviolet excess in their nuclei. An active galactic nucleus is a region at the center of a galaxy that has a higher than normal luminosity over portions of the electromagnetic spectrum. A galaxy having a nucleus is called an active galaxy. Active galactic nuclei are the most luminous sources of radiation in the Universe
Seyfert galaxy
–
The
Circinus Galaxy, a Type II Seyfert galaxy
Seyfert galaxy
–
NGC 1068 (Messier 77), one of the first Seyfert galaxies classified
Seyfert galaxy
–
NGC 5793 is a Seyfert galaxy located over 150 million light-years away in the constellation of Libra.
Seyfert galaxy
–
Optical and ultraviolet images of the black hole in the center of NGC 4151, a Seyfert Galaxy
53.
Astrophysical jet
–
An astrophysical jet is an astronomical phenomenon where outflows of ionised matter are emitted as an extended beam along the axis of rotation. When this greatly accelerated matter in the approaches the speed of light. One possible explanation is that magnetic fields aim two diametrically opposing beams away from the central source by angles only several degrees wide. According to another hypothesis, the jets are due to an effect in general relativity known as frame-dragging, most of the largest and most active jets are created by supermassive black holes in the centre of active galaxies such as quasars and radio galaxies or within galaxy clusters. Such jets can exceed millions of parsecs in length, other astronomical objects that contain jets include cataclysmic variable stars, X-ray binaries and Gamma ray bursters. Others are associated with star forming regions including T Tauri stars and Herbig–Haro objects, bipolar outflows or jets may also be associated with protostars, or with evolved post-AGB stars, planetary nebulae and bipolar nebulae. Relativistic jets are beams of ionised matter accelerated close to the speed of light, most have been observationally associated with central black holes of some active galaxies, radio galaxies or quasars, and also by galactic stellar black holes, neutron stars or pulsars. Beam lengths may extend several thousand, hundreds of thousands or millions of parsecs. Jet velocities when approaching the speed of light show significant effects of the Special Theory of Relativity, for example, massive central black holes in galaxies have the most powerful jets, but their structure and behaviours are similar to those of smaller galactic neutron stars and black holes. These SMBH systems are often called microquasars and show a range of velocities. SS433 jet, for example, has a velocity of 0. 23c, relativistic jet formation may also explain observed gamma-ray bursts. Notably, even weaker and less relativistic jets may be associated with many binary systems, because of the enormous amount of energy needed to launch a relativistic jet, some jets are thought to be powered by spinning black holes. There are two theories for how energy is transferred from a black hole to a jet. This theory explains the extraction of energy from magnetic fields around an accretion disk, relativistic material is then feasibly launched by the tightening of the field lines. Jets may also be observed from spinning neutron stars, an example is pulsar IGR J11014-6103, which has the largest jet so far observed in the Milky Way Galaxy whose velocity is estimated at 80% the speed of light. X-ray observations have been obtained but there is no detected radio signature nor accretion disk, initially, this pulsar was presumed to be rapidly spinning but later measurements indicate the spin rate is only 15.9 Hz. Hubble Video Shows Shock Collision inside Black Hole Jet
Astrophysical jet
–
Relativistic jet. The environment around the
AGN where the
relativistic plasma is collimated into jets which escape along the pole of the
supermassive black hole.
Astrophysical jet
–
Elliptical galaxy M87 emitting a relativistic jet, as seen by the
Hubble Space Telescope.
Astrophysical jet
–
Centaurus A in x-rays showing the relativistic jet
Astrophysical jet
–
The M87 jet seen by the
Very Large Array in
radio frequency (the viewing field is larger and rotated with respect to the above image.)
54.
8P/Tuttle
–
8P/Tuttle is a periodic comet in the Solar System. It fits the definition of a Jupiter-family comet with an orbital period of less than 20 years. Perihelion was late January 2008, and as of February was visible telescopically to Southern Hemisphere observers in the constellation Eridanus, on December 30,2007 it was in close conjunction with spiral galaxy M33. On January 1,2008 it passed Earth at a distance of 0.25282 AU, Comet 8P/Tuttle is responsible for the Ursid meteor shower in late December. Radar observations of Comet Tuttle in January 2008 by the Arecibo Observatory show it to be a contact binary. The comet nucleus is estimated at about 4.5 km in diameter, orbital simulation from JPL / Horizons Ephemeris 8P/Tuttle – Seiichi Yoshida @ aerith. net 8P at Kronks Cometography 8P/Tuttle time sequence Comet Tuttle Seen To Be Returning Comet 8P/Tuttle
8P/Tuttle
–
8P/Tuttle
8P/Tuttle
–
Tuttle on December 3, 2007 from
Mount Laguna,
California
8P/Tuttle
–
Tuttle on Feb 2, 2008 from the
Red Sea coast of
Egypt.
8P/Tuttle
–
Features
55.
Vega
–
It is relatively close at only 25 light-years from the Sun, and, together with Arcturus and Sirius, one of the most luminous stars in the Suns neighborhood. Vega has been studied by astronomers, leading it to be termed “arguably the next most important star in the sky after the Sun. ”Vega was the northern pole star around 12,000 BC. Vega was the first star other than the Sun to be photographed and it was one of the first stars whose distance was estimated through parallax measurements. Vega has served as the baseline for calibrating the photometric brightness scale, Vega has an unusually low abundance of the elements with a higher atomic number than that of helium. Vega is also a star that varies slightly in brightness. It is rotating rapidly with a velocity of 274 km/s at the equator and this is causing the equator to bulge outward because of centrifugal effects, and, as a result, there is a variation of temperature across the stars photosphere that reaches a maximum at the poles. From Earth, Vega is being observed from the direction of one of these poles, based on an observed excess emission of infrared radiation, Vega appears to have a circumstellar disk of dust. This dust is likely to be the result of collisions between objects in a debris disk, which is analogous to the Kuiper belt in the Solar System. Stars that display an infrared excess because of dust emission are termed Vega-like stars, α Lyrae is the stars Bayer designation. The traditional name Vega comes from a transliteration of the Arabic word wāqi‘ meaning falling or landing, via the phrase an-nasr al-wāqi‘. In 2016, the International Astronomical Union organized a Working Group on Star Names to catalog, the WGSNs first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included Vega for this star. It is now so entered in the IAU Catalog of Star Names, astrophotography, the photography of celestial objects, began in 1840 when John William Draper took an image of the Moon using the daguerreotype process. On July 17,1850, Vega became the first star to be photographed, when it was imaged by William Bond and John Adams Whipple at the Harvard College Observatory, also with a daguerreotype. Henry Draper took the first photograph of a spectrum in August 1872 when he took an image of Vega. Similar lines had already identified in the spectrum of the Sun. In 1879, William Huggins used photographs of the spectra of Vega and these were later identified as lines from the Hydrogen Balmer series. Since 1943, the spectrum of this star has served as one of the anchor points by which other stars are classified. The distance to Vega can be determined by measuring its parallax shift against the stars as the Earth orbits the Sun
Vega
–
A mid-infrared (24 μm) image of the
debris disk around Vega
Vega
–
Location of Vega in the constellation
Lyra
Vega
–
Vega through Celestron CGEM DX 1100 @ F6.3, Canon T3i, Televue 4X Powermate, ISO 800, 60 sec exposure
Vega
–
Artist's concept of a recent massive collision of
dwarf planet -sized objects that may have contributed to the dust ring around the
star Vega.
56.
JSTOR
–
JSTOR is a digital library founded in 1995. Originally containing digitized back issues of journals, it now also includes books and primary sources. It provides full-text searches of almost 2,000 journals, more than 8,000 institutions in more than 160 countries have access to JSTOR, most access is by subscription, but some older public domain content is freely available to anyone. William G. Bowen, president of Princeton University from 1972 to 1988, JSTOR originally was conceived as a solution to one of the problems faced by libraries, especially research and university libraries, due to the increasing number of academic journals in existence. Most libraries found it prohibitively expensive in terms of cost and space to maintain a collection of journals. By digitizing many journal titles, JSTOR allowed libraries to outsource the storage of journals with the confidence that they would remain available long-term, online access and full-text search ability improved access dramatically. Bowen initially considered using CD-ROMs for distribution, JSTOR was initiated in 1995 at seven different library sites, and originally encompassed ten economics and history journals. JSTOR access improved based on feedback from its sites. Special software was put in place to make pictures and graphs clear, with the success of this limited project, Bowen and Kevin Guthrie, then-president of JSTOR, wanted to expand the number of participating journals. They met with representatives of the Royal Society of London and an agreement was made to digitize the Philosophical Transactions of the Royal Society dating from its beginning in 1665, the work of adding these volumes to JSTOR was completed by December 2000. The Andrew W. Mellon Foundation funded JSTOR initially, until January 2009 JSTOR operated as an independent, self-sustaining nonprofit organization with offices in New York City and in Ann Arbor, Michigan. JSTOR content is provided by more than 900 publishers, the database contains more than 1,900 journal titles, in more than 50 disciplines. Each object is identified by an integer value, starting at 1. In addition to the site, the JSTOR labs group operates an open service that allows access to the contents of the archives for the purposes of corpus analysis at its Data for Research service. This site offers a facility with graphical indication of the article coverage. Users may create focused sets of articles and then request a dataset containing word and n-gram frequencies and they are notified when the dataset is ready and may download it in either XML or CSV formats. The service does not offer full-text, although academics may request that from JSTOR, JSTOR Plant Science is available in addition to the main site. The materials on JSTOR Plant Science are contributed through the Global Plants Initiative and are only to JSTOR
JSTOR
–
The JSTOR front page
57.
Virgilius
–
Publius Vergilius Maro, usually called Virgil or Vergil /ˈvɜːrdʒᵻl/ in English, was an ancient Roman poet of the Augustan period. He wrote three of the most famous poems in Latin literature, the Eclogues, the Georgics, a number of minor poems, collected in the Appendix Vergiliana, are sometimes attributed to him. Virgil is traditionally ranked as one of Romes greatest poets and his Aeneid has been considered the national epic of ancient Rome from the time of its composition to the present day. Virgils work has had wide and deep influence on Western literature, most notably Dantes Divine Comedy, in which Virgil appears as Dantes guide through Hell, the tradition holds that Virgil was born in the village of Andes, near Mantua in Cisalpine Gaul. Analysis of his name has led to beliefs that he descended from earlier Roman colonists, modern speculation ultimately is not supported by narrative evidence either from his own writings or his later biographers. Macrobius says that Virgils father was of a background, however. He attended schools in Cremona, Mediolanum, Rome and Naples, after considering briefly a career in rhetoric and law, the young Virgil turned his talents to poetry. From Virgils admiring references to the neoteric writers Pollio and Cinna, it has been inferred that he was, for a time, according to Servius, schoolmates considered Virgil extremely shy and reserved, and he was nicknamed Parthenias or maiden because of his social aloofness. Virgil also seems to have suffered bad health throughout his life, according to the Catalepton, he began to write poetry while in the Epicurean school of Siro the Epicurean at Naples. A group of works attributed to the youthful Virgil by the commentators survive collected under the title Appendix Vergiliana. One, the Catalepton, consists of fourteen poems, some of which may be Virgils, and another. The biographical tradition asserts that Virgil began the hexameter Eclogues in 42 BC and it is thought that the collection was published around 39–38 BC, the Eclogues are a group of ten poems roughly modeled on the bucolic hexameter poetry of the Hellenistic poet Theocritus. The loss of his farm and the attempt through poetic petitions to regain his property have traditionally been seen as Virgils motives in the composition of the Eclogues. This is now thought to be an unsupported inference from interpretations of the Eclogues, the ten Eclogues present traditional pastoral themes with a fresh perspective. Eclogues 1 and 9 address the land confiscations and their effects on the Italian countryside,2 and 3 are pastoral and erotic, discussing both homosexual love and attraction toward people of any gender. Eclogue 4, addressed to Asinius Pollio, the so-called Messianic Eclogue uses the imagery of the age in connection with the birth of a child. Virgil came to many of the other leading literary figures of the time, including Horace, in whose poetry he is often mentioned, and Varius Rufus. At Maecenas insistence Virgil spent the years on the long didactic hexameter poem called the Georgics which he dedicated to Maecenas
Virgilius
–
Depiction of Virgil, 3rd century AD ("Monnus-Mosaic",
Rheinisches Landesmuseum,
Trier)
Virgilius
–
A
bust of Virgil in
Naples
Virgilius
–
Page from the Eclogues in the 5th-century Vergilius Romanus
Virgilius
–
Late 17th-century illustration of a passage from the Georgics by
Jerzy Siemiginowski-Eleuter
58.
Johann Heinrich Alsted
–
His contemporaries noted that an anagram of Alstedius was sedulitas, meaning hard work in Latin. He was educated at Herborn Academy in the state of Hesse, from 1606 he was at the University of Marburg, taught by Rudolf Goclenius, Gregorius Schönfeld and Raphaël Egli. The following year he went to Basel, where his teachers were Leonhardt Zubler for mathematics, Amandus Polanus von Polansdorf for theology, from about 1608 he returned to the Herborn Academy to teach as professor of philosophy and theology. Alsted was later in exile from the Thirty Years War in Transylvania, in 1629 he left war-torn Germany for Weißenburg. He was to found a Calvinist Academy, the context was that the Transylvanian royal family had just returned from Unitarianism to Calvinism, Alsted and Johannes Bisterfeld were German professors brought in improve standards. Among the students there was János Apáczai Csere, Alsted has been called one of the most important encyclopedists of all time. He was a writer, and his Encyclopaedia long had a high reputation. It was preceded by works, including the 1608 Encyclopaedia cursus philosophici. His major encyclopedia of 1630, the Encyclopaedia, Septem Tomis Distincta, was divided into 35 books, in its time it was praised by Bernard Lamy, and criticised for plagiarism for verbatim copying without acknowledgment by Jacob Thomasius. Augustus De Morgan later called it the parent of all the Encyclopædias, or collections of treatises. The Cambridge History of Renaissance Philosophy, p and it was reissued as a 4-volume facsimile reprint, edited by W. Schmidt-Biggemann. In 1610, Alstedius published the first edition of his Encyclopedia, in 1630, he published a second edition in a much more comprehensive form, in two large folio volumes. In the second edition, he professes to reduce the several branches of art and science then known, in this work, and his Encyclopedia Biblica, he tries to prove that the foundation and materials of the whole can be found in the Sacred Scriptures. The first four contain an exposition of the various subjects to be discussed. He devotes six books to philology, ten to speculative philosophy, then follow three on theology, jurisprudence, and medicine, three on mechanical arts, and five on history, chronologym, and miscellanies. This work exhibited an improvement on other published works that purported to be encyclopedias in the latter half of the 16th. In writing a semi-Ramist encyclopedia, he applied his conception of logic to the sum of human knowledge. To do that, he added the Lullist topical art of memory to Ramist topical logic and he had a reputation in his own time as a distinctive methodologist
Johann Heinrich Alsted
–
Johann Heinrich Alsted.
59.
William Tyler Olcott
–
William Tyler Olcott was an American lawyer and amateur astronomer. In 1909, after attending a lecture by Edward Charles Pickering, in 1911, he founded the American Association of Variable Star Observers. W. Olcott also published books to popularize the field of amateur astronomy. AAVSO Merit Award The William Tyler Olcott Award of the AAVSO, the crater Olcott on the Moon is named after him. W. T. Olcott, In Starland With A Three-Inch Telescope,1909, New York, W. T. Olcott, Variable Star Work for the Amateur Astronomer,1911, Popular Astronomy. W. T. Olcott, Star Lore of All Ages,1911, New York, G. P. Putnams Sons. Works by William Tyler Olcott at Project Gutenberg Works by William Tyler Olcott at Faded Page Works by or about William Tyler Olcott at Internet Archive Sun Lore of All Ages, at sacred-texts. com
William Tyler Olcott
–
v
60.
Henry Norris Russell
–
Henry Norris Russell was an American astronomer who, along with Ejnar Hertzsprung, developed the Hertzsprung–Russell diagram. In 1923, working with Frederick Saunders, he developed Russell–Saunders coupling which is known as LS coupling. Russell was born in 1877 in Oyster Bay, New York and he studied astronomy at Princeton University, obtaining his B. A. In 1897 and his doctorate in 1899, studying under Charles Augustus Young, from 1903 to 1905, he worked at the Cambridge Observatory with Arthur Robert Hinks as a research assistant of the Carnegie Institution and came under the strong influence of George Darwin. He returned to Princeton to become an instructor in astronomy, assistant professor, professor and he was also the director of the Princeton University Observatory from 1912 to 1947. He died in Princeton, New Jersey in 1957 at the age of 79, in November 1908 Russell married Lucy May Cole. Their youngest daughter, Margaret, married the astronomer Frank K. Edmondson in the 1930s, Russell co-wrote an influential two-volume textbook in 1927 with Raymond Smith Dugan and John Quincy Stewart, Astronomy, A Revision of Young’s Manual of Astronomy. This became the standard textbook for about two decades. There were two volumes, the first was The Solar System and the second was Astrophysics and Stellar Astronomy, the textbook popularized the idea that a stars properties were largely determined by the stars mass and chemical composition, which became known as the Vogt-Russell theorem. Since a stars chemical composition changes with age, stellar evolution results. However, he changed his mind four years later after deriving the same result by different means, after Payne was proven correct, Russell briefly credited Payne for discovering that the Sun had a different chemical composition from Earth in his paper. However the credit was given to him instead. Henry Norris Russell, Frederick Albert Saunders, New Regularities in the Spectra of the Alkaline Earths. Henry Norris Russell, Raymond Smith Dugan, John Quincy Stewart, Astronomy, A Revision of Young’s Manual of Astronomy, Vol. I, The Solar System, Vol. II, Astrophysics and Stellar Astronomy. Boston, Ginn & Co. Henry Norris Russell, on the Composition of the Suns Atmosphere
Henry Norris Russell
–
Henry Norris Russell
61.
Astrophysics and Space Science
–
Astrophysics and Space Science is a bimonthly peer-reviewed scientific journal covering astronomy, astrophysics, and space science and astrophysical aspects of astrobiology. It was established in 1968 and is published by Springer Science+Business Media, the editor-in-chief is Michael A. Dopita. The journal is abtracted and indexed in the databases, According to the Journal Citation Reports
Astrophysics and Space Science
–
Astrophysics and Space Science
62.
J. Davy Kirkpatrick
–
J. Davy Kirkpatrick is an American astronomer at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, California. Kirkpatricks research was named one of the top ten science accomplishments of the first ten years of the W. M. Keck Observatory, Kirkpatrick received a BS in mathematics and physics/astronomy from Vanderbilt University in 1986 and a PhD in astronomy from the University of Arizona in 1992. Much of Kirkpatricks research has concentrated on the discovery and characterization of the lowest mass stars, along with Neill Reid, he uncovered many objects similar to and colder than GD 165B, leading to the definition of the L dwarf spectral class. Also using 2MASS data, he and graduate student Adam Burgasser discovered brown dwarfs even colder than spectral class L, along with Adam Burgasser and Chris Gelino, Kirkpatrick maintains a listing of all known L, T, and Y dwarf discoveries at the DwarfArchives website. Kirkpatrick is credited with first using the name Tyche to refer to a heretofore unseen and he chose this term to be in direct contrast to Nemesis, an unseen Solar companion hypothesized to lie in a highly elliptical orbit and to be responsible for periodic mass extinctions on the Earth. Kirkpatricks own search using the 2MASS data set out any Solar companion more massive than 30 Jupiter masses. New Spectral Types L and T from Annual Review of Astronomy and Astrophysics,2005 M Dwarfs and L Dwarfs, Chapter 9 of Stellar Spectral Classification 2011 Wendell G
J. Davy Kirkpatrick
–
J. Davy Kirkpatrick
63.
Antlia
–
Antlia is a constellation in the Southern Celestial Hemisphere. Its name means pump in Latin, it represents an air pump, originally Antlia Pneumatica, the constellation was established by Nicolas-Louis de Lacaille in the 18th century, though its name was later abbreviated by John Herschel. Located close to the forming the old constellation of the ship Argo Navis. Antlia is a faint constellation, its brightest star is Alpha Antliae, S Antliae is an eclipsing binary star system, changing in brightness as one star passes in front of the other. Sharing a common envelope, the stars are so close they will one day merge to form a single star, two star systems with known exoplanets, HD93083 and WASP-66, lie within Antlia, as do NGC2997, a spiral galaxy, and the Antlia Dwarf Galaxy. He named all but one in honour of instruments that symbolised the Age of Enlightenment, Lacaille depicted Antlia as a single-cylinder vacuum pump used in Papins initial experiments, while German astronomer Johann Bode chose the more advanced double-cylinder version. Lacaille Latinised the name to Antlia pneumatica on his 1763 chart, english astronomer John Herschel proposed shrinking the name to one word in 1844, noting that Lacaille himself had abbreviated his constellations thus on occasion. The International Astronomical Union adopted it as one of the 88 modern constellations in 1922, although above the horizon and hence visible to the Ancient Greeks, Antlias stars were too faint to have been included in any ancient constellations. Ridpath reports that due to their faintness, the stars of Antlia did not make up part of the depiction of Argo Navis. Chinese astronomers were able to view what is modern Antlia from their latitudes, several stars in the southern part of Antlia were a portion of Dongou, which represented an area in southern China. Furthermore, Epsilon, Eta, and Theta Antliae were incorporated into the celestial temple, covering 238.9 square degrees and hence 0. 579% of the sky, Antlia ranks 62nd of the 88 modern constellations by area. Its position in the Southern Celestial Hemisphere means that the constellation is visible to observers south of 49°N. Hydra the sea runs along the length of its northern border, while Pyxis the compass, Vela the sails. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union, is Ant, the official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of twelve segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 09h 26. 5m and 11h 05. 6m, while the coordinates are between −24. 54° and −40. 42°. Lacaille gave nine stars Bayer designations, labelling them Alpha through to Theta, gould later added a tenth, Iota Antliae. Beta and Gamma Antliae ended up in the neighbouring constellation Hydra once the boundaries were delineated in 1930. Within the constellations borders, there are 42 stars brighter than or equal to apparent magnitude 6.5, the constellations two brightest stars—Alpha and Epsilon Antliae—shine with a reddish tinge
Antlia
–
Johann Bode's depiction of Antlia.
Antlia
–
List of stars in Antlia
Antlia
–
The constellation Antlia as it can be seen by the naked eye.
Antlia
–
A composite image of NGC 2997.
64.
Apus
–
Apus is a small constellation in the southern sky. It represents a bird-of-paradise, and its name means without feet in Greek because the bird-of-paradise was once believed to lack feet. First depicted on a celestial globe by Petrus Plancius in 1598, the French explorer and astronomer Nicolas Louis de Lacaille charted and gave the brighter stars their Bayer designations in 1756. The five brightest stars are all reddish in hue, shading the others at apparent magnitude 3.8 is Alpha Apodis, an orange giant that has around 48 times the diameter and 928 times the luminosity of the Sun. Marginally fainter is Gamma Apodis, another ageing giant star, Delta Apodis is a double star, the two components of which are 103 arcseconds apart and visible with the naked eye. Two star systems have found to have planets. It first appeared on a 35-cm diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius, Apis is presumably a typographical error for avis. After its introduction on Planciuss globe, the constellations first known appearance in an atlas was in German cartographer Johann Bayers Uranometria of 1603. Bayer called it Apis Indica while fellow astronomers Johannes Kepler and his son-in-law Jakob Bartsch called it Apus or Avis Indica, the name Apus is derived from the Greek apous, meaning without feet. This referred to the Western misconception that the bird-of-paradise had no feet, such specimens began to arrive in Europe in 1522, when the survivors of Ferdinand Magellans expedition brought them home. The constellation later lost some of its tail when Nicolas-Louis de Lacaille used those stars to establish Octans in the 1750s, covering 206.3 square degrees and hence 0. 5002% of the sky, Apus ranks 67th of the 88 modern constellations by area. Its position in the Southern Celestial Hemisphere means that the constellation is visible to observers south of 7°N. It is bordered by Ara, Triangulum Australe and Circinus to the north, Musca and Chamaeleon to the west, Octans to the south, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Aps. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of six segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 13h 49. 5m and 18h 27. 3m, while the coordinates are between −67. 48° and −83. 12°. Lacaille gave twelve stars Bayer designations, labelling them Alpha through to Kappa, within the constellations borders, there are 39 stars brighter than or equal to apparent magnitude 6.5. Beta, Gamma and Delta Apodis form a triangle, with Alpha Apodis lying to the east. The five brightest stars are all red-tinged, which is unusual among constellations, Alpha Apodis is an orange giant of spectral type K3III located 447 ±8 light years away from Earth, with an apparent magnitude of 3.8
Apus
–
The constellation Apus as it can be seen by the naked eye.
Apus
–
List of stars in Apus
Apus
–
Globular cluster IC 4499 taken by
Hubble Space Telescope.
65.
Ara (constellation)
–
Ara is a southern constellation situated between Scorpius and Triangulum Australe. Ara was one of the 48 Greek constellations described by the 2nd century astronomer Ptolemy, the orange supergiant Beta Arae is the brightest star in the constellation, with an apparent magnitude of 2. 85—marginally brighter than the blue-white Alpha Arae. The sunlike star Mu Arae hosts four planets, while Gliese 676 is a red dwarf system with four planets. The Milky Way crosses the northwestern part of Ara, in ancient Greek mythology, Ara was identified as the altar where the gods first made offerings and formed an alliance before defeating the Titans. The nearby Milky Way represents the rising from the offerings on the altar. It had been recorded by Aratus in 270 BCE as lying close to the horizon, professor of astronomy Bradley Schaefer has proposed that ancient observers must have been able to see as far south as Zeta Arae to define a pattern that looked like an altar. In illustrations, Ara is usually depicted as an altar with its smoke rising southward, however, depictions of Ara often vary in their details. In the early days of printing, a 1482 woodcut of Gaius Julius Hyginuss classic Poeticon Astronomicon depicts the altar as surrounded by demons, johann Bayer in 1603 depicted Ara as an altar with burning incense, the flames rise southward as in most atlases. Hyginus also depicted Ara as an altar with burning incense, though his Ara featured devils on either side of the flames. However, Willem Blaeu, a Dutch uranographer active in the 16th and 17th centuries, drew Ara as a designed for sacrifice. Unlike most depictions, the smoke from Blaeus Ara rises northward, in Chinese astronomy, the stars of the constellation Ara lie within The Azure Dragon of the East. Five stars of Ara formed Guī, a tortoise, while another three formed Chǔ, a pestle, covering 237.1 square degrees and hence 0. 575% of the sky, Ara ranks 63rd of the 88 modern constellations by area. Its position in the Southern Celestial Hemisphere means that the constellation is visible to observers south of 22°N. Scorpius runs along the length of its border, while Norma and Triangulum Australe line it to the west, Apus to the south. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union, is Ara, the official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of twelve segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 16h 36. 1m and 18h 10. 4m, while the coordinates are between −45. 49° and −67. 69°. Bayer gave eight stars Bayer designations, labelling them Alpha through to Theta, after charting the southern constellations, Lacaille recharted the stars of Ara from Alpha though to Sigma, including three pairs of stars next to each other as Epsilon, Kappa and Nu. Ara contains part of the Milky Way to the south of Scorpius and thus has rich star fields, within the constellations borders, there are 71 stars brighter than or equal to apparent magnitude 6.5
Ara (constellation)
–
The constellation Ara as it can be seen by the naked eye.
Ara (constellation)
–
List of stars in Ara
Ara (constellation)
–
Johann Elert Bode 's illustration of Ara, from his Uranographia (1801)
66.
Auriga (constellation)
–
Auriga is one of the 88 modern constellations, it was among the 48 constellations listed by the 2nd-century astronomer Ptolemy. Located north of the equator, its name is the Latin word for charioteer, associating it with various mythological charioteers. Auriga is most prominent during winter evenings in the northern Hemisphere, because of its northern declination, Auriga is only visible in its entirety as far as 34° south, for observers farther south it lies partially or fully below the horizon. A large constellation, with an area of 657 square degrees, it is half the size of the largest constellation and its brightest star, Capella, is an unusual multiple star system among the brightest stars in the night sky. Beta Aurigae is a variable star in the constellation, Epsilon Aurigae. Because of its position near the winter Milky Way, Auriga has many open clusters in its borders, including M36, M37. In addition, it has one prominent nebula, the Flaming Star Nebula, in Chinese mythology, Aurigas stars were incorporated into several constellations, including the celestial emperors chariots, made up of the modern constellations brightest stars. Auriga is home to the radiant for the Aurigids, Zeta Aurigids, Delta Aurigids, the first record of Aurigas stars was in Mesopotamia as a constellation called GAM, representing a scimitar or crook. However, this may have represented just Capella or the constellation as a whole. The crook of Auriga stood for a goat-herd or shepherd and it was formed from most of the stars of the modern constellation, all of the bright stars were included except for Elnath, traditionally assigned to both Taurus and Auriga. Later, Bedouin astronomers created constellations that were groups of animals, the stars of Auriga comprised a herd of goats, an association also present in Greek mythology. The association with goats carried into the Greek astronomical tradition, though it became associated with a charioteer along with the shepherd. In Greek mythology, Auriga is often identified as the mythological Greek hero Erichthonius of Athens and his chariot was created in the image of the Suns chariot, the reason Zeus placed him in the heavens. The Athenian hero then dedicated himself to Athena and, soon after, Zeus raised him into the sky in honor of his ingenuity. Auriga, however, is described as Myrtilus, who was Hermess son. The association of Auriga and Myrtilus is supported by depictions of the constellation, Myrtiluss chariot was destroyed in a race intended for suitors to win the heart of Oenomauss daughter Hippodamia. Myrtilus earned his position in the sky when Hippodamias successful suitor, Pelops, killed him, after his death, Myrtiluss father Hermes placed him in the sky. Yet another mythological association of Auriga is Theseuss son Hippolytus and he was ejected from Athens after he refused the romantic advances of his stepmother Phaedra, who committed suicide as a result
Auriga (constellation)
–
A painting by
Peter Paul Rubens entitled Finding of Erichthonius; Erichthonius and Auriga are often associated.
Auriga (constellation)
–
List of stars in Auriga
Auriga (constellation)
–
Auriga carrying the goat and kids as depicted in
Urania's Mirror, a set of constellation cards illustrated by Sidney Hall, London circa 1825.
Auriga (constellation)
–
The constellation Auriga as it can be seen by the naked eye.
67.
Canes Venatici
–
Canes Venatici /ˈkeɪniːz vᵻˈnætᵻsaɪ/ is one of the 88 official modern constellations. It is a northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for hunting dogs, and the constellation is depicted in illustrations as representing the dogs of Boötes the Herdsman. The stars of Canes Venatici are not bright, in classical times, they were listed by Ptolemy as unfigured stars below the constellation Ursa Major in his star catalogue. In medieval times, the identification of these stars with the dogs of Boötes arose through a mistranslation, some of Boötess stars were traditionally described as representing the club of Boötes. When the Arabic text was translated into Latin, the translator Gerard of Cremona mistook the Arabic word كلاب for kilāb, meaning dogs. In 1533, the German astronomer Peter Apian depicted Boötes as having two dogs with him and these spurious dogs floated about the astronomical literature until Hevelius decided to specify their presence in the sky by making them a separate constellation in 1687. Hevelius chose the name Asterion for the dog and Chara for the southern dog, as Canes Venatici. In his star catalogue, the Czech astronomer Bečvář assigned the names Asterion to β CVn, Canes Venatici is bordered by Ursa Major to the north and west, Coma Berenices to the south, and Boötes to the east. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is CVn, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 14 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 12h 06. 2m and 14h 07. 3m, while the coordinates are between +27. 84° and +52. 36°. Covering 465 square degrees, it ranks 38th of the 88 constellations in size, Canes Venatici contains no bright stars, α and β CVn being only of 3rd and 4th magnitude respectively. Flamsteed catalogued 25 stars in the constellation, labelling them 1 to 25 Canum Venaticorum, α CVn is the constellations brightest star, named by Sir Charles Scarborough in memory of King Charles I, the deposed king of Britain. Legend has it that α CVn was brighter than usual during the Restoration, cor Caroli is a wide double star, with a primary of magnitude 2.9 and a secondary of magnitude 5.6, the primary is 110 light-years from Earth. The primary also has an unusually strong variable magnetic field, β CVn is a yellow-hued main sequence star of magnitude 4.2,27 light-years from Earth. Its common name comes from the word for joy, Y CVn is a semiregular variable star that varies between magnitudes 5.0 and 6.5 over a period of around 158 days. It is a star and is being deep red in color. AM CVn, a blue star of magnitude 14, is the prototype of a special class of cataclysmic variable stars, in which the companion star is a white dwarf
Canes Venatici
–
Canes Venatici can be seen in the orientation they appear to the eyes in this 1825 star chart from
Urania's Mirror.
Canes Venatici
–
List of stars in Canes Venatici
Canes Venatici
–
The constellation Canes Venatici as it can be seen by the naked eye.
Canes Venatici
–
Messier 51, the Whirlpool Galaxy taken by the
Hubble Space Telescope.
68.
Canis Minor
–
Canis Minor /ˌkeɪnᵻs ˈmaɪnər/ is a small constellation in the northern celestial hemisphere. In the second century, it was included as an asterism, or pattern and its name is Latin for lesser dog, in contrast to Canis Major, the greater dog, both figures are commonly represented as following the constellation of Orion the hunter. Canis Minor contains only two stars brighter than the magnitude, Procyon, with a magnitude of 0.34. The constellations dimmer stars were noted by Johann Bayer, who named eight stars including Alpha and Beta, and John Flamsteed, Procyon is the seventh-brightest star in the night sky, as well as one of the closest. A yellow-white main sequence star, it has a white dwarf companion, Gomeisa is a blue-white main sequence star. Luytens Star is a red dwarf and the Solar Systems next closest stellar neighbour in the constellation after Procyon. The fourth-magnitude HD66141, which has evolved into an orange giant towards the end of its cycle, was discovered to have a planet in 2012. There are two faint deep sky objects within the constellations borders, the 11 Canis-Minorids are a meteor shower that can be seen in early December. Though strongly associated with the Classical Greek uranographic tradition, Canis Minor originates from ancient Mesopotamia, Procyon and Gomeisa were called MASH. TAB. BA or twins in the Three Stars Each tablets, dating to around 1100 BC. In the later MUL. APIN, this name was applied to the pairs of Pi3 and Pi4 Orionis and Zeta. The meaning of MASH. TAB. BA evolved as well, becoming the twin deities Lulal and Latarak, who are on the side of the sky from Papsukal. Canis Minor was also given the name DAR. LUGAL, which translates to the star which stands behind it, in the MUL. APIN and this name may have also referred to the constellation Lepus. DAR. LUGAL was also denoted DAR. MUŠEN and DAR. LUGAL. MUŠEN in Babylonia, Canis Minor was then called tarlugallu in Akkadian astronomy. The Ancient Greeks called the constellation προκυων/Procyon, coming before the dog, transliterated into Latin as Antecanis, Praecanis, or variations thereof, by Cicero, roman writers also appended the descriptors parvus, minor or minusculus, septentrionalis, primus or sinister to its name Canis. In Greek mythology, Canis Minor was sometimes connected with the Teumessian Fox, a beast turned into stone with its hunter, Laelaps, by Zeus, eratosthenes accompanied the Little Dog with Orion, while Hyginus linked the constellation with Maera, a dog owned by Icarius of Athens. On discovering the death, the dog and Icarius daughter Erigone took their lives. As a reward for his faithfulness, the dog was placed along the banks of the Milky Way, which the ancients believed to be a heavenly river, among the Merazig of Tunisia, shepherds note six constellations that mark the passage of the dry, hot season. One of them, called Merzem, includes the stars of Canis Minor, the ancient Egyptians thought of this constellation as Anubis, the jackal god
Canis Minor
–
Canis Minor, as depicted by
Johann Bode in his 1801 work Uranographia
Canis Minor
–
List of stars in Canis Minor
Canis Minor
–
The constellation Canis Minor can be seen alongside
Monoceros and the obsolete constellation
Atelier Typographique in this 1825 star chart from
Urania's Mirror.
Canis Minor
–
The constellation Canis Minor as it can be seen by the naked eye
69.
Cetus
–
Its name refers to Cetus, a sea monster in Greek mythology, although it is often called the whale today. Cetus is located in the region of the sky that contains other water-related constellations such as Aquarius, Pisces and this is all the more true of asteroids, since their orbits usually have a greater inclination to the ecliptic than the moon and planets. For example, the asteroid 4 Vesta was discovered in this constellation in 1807, as seen from Mars, the ecliptic passes into Cetus, with the sun appearing in Cetus for around six days shortly after the northern summer solstice. Marss orbit is tilted by 1. 85° with respect to Earths, Mira, designated Omicron Ceti, was the first variable star to be discovered and the prototype of its class. Over a period of 332 days it reaches an apparent magnitude of 3 - visible to the naked eye - and dips to a minimum magnitude of 10. Its seeming appearance and disappearance gave it its name, which means the amazing one. Mira pulsates with a size of 400 solar diameters and a maximum size of 500 solar diameters. 420 light-years from Earth, it was discovered by David Fabricius in 1596, α Ceti, traditionally called Menkar, is a red-hued giant star of magnitude 2.5,220 light-years from Earth. It is a double star, the secondary is 93 Ceti. β Ceti, also called Deneb Kaitos and Diphda, is the brightest star in Cetus and it is an orange-hued giant star of magnitude 2.0,96 light-years from Earth. The traditional name Deneb Kaitos means the whales tail, γ Ceti, Kaffaljidhma is a very close double star. The primary is a star of magnitude 3.5,82 light-years from Earth. Tau Ceti is noted for being the nearest Sun-like star at a distance of 11.9 light-years and it is a yellow-hued main-sequence star of magnitude 3.5. AA Ceti is a star system, the brightest member has a magnitude of 6.2. The primary and secondary are separated by 8.4 arcseconds at an angle of 304 degrees, the tertiary is not visible in telescopes. AA Ceti is a variable star, the tertiary star passes in front of the primary. UV Ceti is a binary variable star. 8.7 light-years from Earth, the system consists of two red dwarfs, one of the stars is a flare star, which are prone to sudden, random outbursts that last several minutes, these increase the pairs apparent brightness significantly - as high as magnitude 7
Cetus
–
The constellation Cetus as it can be seen by the naked eye.
Cetus
–
List of stars in Cetus
Cetus
–
Messier 77 spiral galaxy by HST.
Cetus
–
Cetus dominates this card from
Urania's Mirror (1825).
70.
Chamaeleon
–
Chamaeleon is a small constellation in the southern sky. It is named after the chameleon, a kind of lizard and it was first defined in the 16th century. Chamaeleon was one of twelve created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser. It first appeared on a 35-cm diameter celestial globe published in 1597 in Amsterdam by Plancius and Jodocus Hondius, johann Bayer was the first uranographer to put Chamaeleon in a celestial atlas. It was one of many created by European explorers in the 15th and 16th centuries out of unfamiliar Southern Hemisphere stars. There are four stars in Chamaeleon. Alpha Chamaeleontis is a star of magnitude 4.1,63 light-years from Earth. Beta Chamaeleontis is a blue-white hued star of magnitude 4.2,27 light-years from Earth, gamma Chamaeleontis is a red-hued giant star of magnitude 4.1,413 light-years from Earth. The other bright star in Chamaeleon is Delta Chamaeleontis, a double star. The brighter star is Delta2 Chamaeleontis, a star of magnitude 4.4,364 light-years from Earth. Delta1 Chamaeleontis, the component, is an orange-hued giant star of magnitude 5.5,354 light-years away. Chamaeleon is also the location of Cha 110913, a dwarf star or proto solar system. In 1999, a open cluster was discovered centered on the star η Chamaeleontis. The cluster, known as either the Eta Chamaeleontis cluster or Mamajek 1, is 8 million years old, the constellation contains a number of molecular clouds that are forming low-mass T Tauri stars. The cloud complex lies some 400 to 600 light years from Earth, the most prominent cluster of T Tauri stars and young B-type stars are in the Chamaeleon I cloud, and are associated with the reflection nebula IC2631. Chamaeleon contains one planetary nebula, NGC3195, which is fairly faint and it appears in a telescope at about the same apparent size as Jupiter. In Chinese astronomy, the stars that form Chamaeleon were classified as the Little Dipper among the Southern Asterisms by Xu Guangqi. W
Chamaeleon
–
The constellation Chamaeleon as it can be seen by the naked eye.
Chamaeleon
–
List of stars in Chamaeleon
71.
Circinus
–
Circinus is a small, faint constellation in the southern sky, first defined in 1756 by the French astronomer Nicolas-Louis de Lacaille. Its name is Latin for compass, referring to the tool used for drawing circles. Its brightest star is Alpha Circini, with an apparent magnitude of 3.19, slightly variable, it is the brightest rapidly oscillating Ap star in the night sky. AX Circini is a Cepheid variable visible with the unaided eye, two sun-like stars have planetary systems, HD134060 has two small planets, and HD129445 has a Jupiter-like planet. Supernova SN185 appeared in Circinus in 185 AD and was recorded by Chinese observers, two novae have been observed more recently, in the 20th century. The Milky Way runs through the constellation, featuring prominent objects such as the open cluster NGC5823, Circinus hosts a spiral galaxy, the Circinus Galaxy, which was discovered in 1977 and is the closest Seyfert galaxy to the Milky Way. The Alpha Circinids, a meteor shower also discovered in 1977, Circinus was given its current name in 1763, when Lacaille published an updated sky map with Latin names for the constellations he introduced. Bordered by Centaurus, Musca, Apus, Triangulum Australe, Norma and Lupus, Circinus lies adjacent to the Alpha, as it is at declination −50° to −70°, the whole constellation is only visible south of latitude 30° N. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 14 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 13h 38. 4m and 15h 30. 2m, and the coordinates are between −55. 43° and −70. 62°. Circinus culminates each year at 9 p. m. on 30 July, the recommended three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Cir. Circinus is a faint constellation, with one star brighter than fourth magnitude. Alpha Circini, a main sequence star with an apparent magnitude of 3.19, is 54 light-years away. Not only the brightest star in the constellation, it is also the brightest example of a rapidly oscillating Ap star in the night sky and it has the unusual spectral type A7 Vp SrCrE, showing increased emissions of strontium, chromium and europium. Stars of this type have oddly localised magnetic fields and are slightly variable, Alpha Circini forms a binary star system with an orange dwarf companion of spectral type K5 and magnitude 8.5, which with a separation of 5.7 arcseconds is only discernible with a telescope. The distance between the two stars is 260 AU and they take 2600 years to rotate around a centre of gravity. The second brightest star is Beta Circini, a main sequence star of spectral type A3Va. It has around 1.8 times the diameter of the Sun, gamma Circini is a binary star 450 light-years away, whose components need a telescope of 150 mm to be seen, as they are only 0.8 arcseconds apart
Circinus
–
The constellation Circinus as it can be seen by the naked eye
Circinus
–
List of stars in Circinus
Circinus
–
An astrophotograph of
NGC 5823, showing its backwards S shape
Circinus
–
Hubble Space Telescope 's view of NGC 5315, showing its intricate structure and central star
72.
Coma Berenices
–
Coma Berenices is an ancient asterism in the northern sky which has been defined as one of the 88 modern constellations. It is located in the fourth quadrant, between Leo and Bootes, and is visible in both hemispheres. It was introduced to Western astronomy during the third century BC by Conon of Samos and its name means Berenices Hair in Latin and refers to Queen Berenice II of Egypt, who sacrificed her long hair as a votive offering. Coma Berenices is the modern constellation named for an historic figure. It was further corroborated as a constellation by Gerardus Mercator and Tycho Brahe, three of the constellations stars are visible to the naked eye, Alpha Comae Berenices, Beta Comae Berenices and Gamma Comae Berenices. They form a 45-degree triangle, from which Berenices imaginary tresses hang, the constellations brightest star is Beta Comae Berenices, a 4. 2-magnitude main sequence star similar to the Sun. Coma Berenices contains the North Galactic Pole and one of the richest known galaxy clusters, Galaxy Malin 1, in the constellation, is the first known giant low-surface-brightness galaxy. Supernova SN 2005ap discovered in Coma Berenices is the brightest known, the star FK Comae Berenices is the prototype of an eponymous class of variable stars. The constellation is the radiant of one meteor shower, Coma Berenicids, Coma Berenices has been recognized as an asterism since the Hellenistic period, and is the only modern constellation named for an historic figure. It was introduced to Western astronomy during the third century BC by Conon of Samos, Berenice vowed to sacrifice her long hair as a votive offering if Ptolemy returned safely from battle during the Third Syrian War. In Callimachus poem, Aetia, Berenice dedicated her tresses to all the gods, in the Latin translation of the poem by the Roman poet Catullus and in Hyginus De astronomica, she dedicated her tresses to Aphrodite and placed them in the temple of Arsinoe II at Zephyrium. According to De astronomica, by the morning the tresses had disappeared. Conon proposed that Aphrodite had placed the tresses in the sky as an acknowledgement of Berenices sacrifice, Callimachus called the asterism plokamos Berenikēs or bostrukhon Berenikēs in Greek, translated into Latin as Coma Berenices by Catullus. Eratosthenes called it Berenices Hair and Ariadnes Hair, considering it part of the constellation Leo, the astronomer Geminus recognized it as a distinct constellation. Astronomer Ptolemy considered it part of Leo, and called it Plokamos, Coma Berenices became popular during the 16th century. In 1515, a set of gores by Johannes Schöner labelled the asterism Trica, in 1536 it appeared on a celestial globe by Caspar Vopel, who is credited with the asterisms designation as a constellation. That year, it appeared on a celestial map by Petrus Apianus as Crines Berenices. In 1551, Coma Berenices appeared on a celestial globe by Gerardus Mercator with five Latin and Greek names, Cincinnus, caesaries, πλόκαμος, Berenicis crinis, mercators reputation as a cartographer ensured the constellations inclusion on Dutch sky globes beginning in 1589
Coma Berenices
–
Queen Berenice II of Egypt
Coma Berenices
–
List of stars in Coma Berenices
Coma Berenices
–
Plate by
Sidney Hall and Richard Rouse Bloxam from
Urania's Mirror. Coma Berenices can be seen on the right.
Coma Berenices
–
The constellation Coma Berenices as it can be seen by the naked eye.
73.
Corona Australis
–
Corona Australis or Corona Austrina is a constellation in the Southern Celestial Hemisphere. Its Latin name means southern crown, and it is the counterpart of Corona Borealis. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, the Ancient Greeks saw Corona Australis as a wreath rather than a crown and associated it with Sagittarius or Centaurus. Other cultures have likened the pattern to a turtle, ostrich nest, although fainter than its namesake, the oval- or horseshoe-shaped pattern of its brighter stars renders it distinctive. Alpha and Beta Coronae Australis are the two brightest stars with an apparent magnitude of around 4.1, Epsilon Coronae Australis is the brightest example of a W Ursae Majoris variable in the southern sky. Within it are stars at the earliest stages of their lifespan, the variable stars R and TY Coronae Australis light up parts of the nebula, which varies in brightness accordingly. The name of the constellation was entered as Corona Australis when the International Astronomical Union established the 88 modern constellations in 1922, in 1932, the name was instead recorded as Corona Austrina when the IAUs commission on notation approved a list of four-letter abbreviations for the constellations. Although the four-letter abbreviations were repealed in 1955, this name has persisted alongside the original. The IAU presently uses Corona Australis exclusively, Corona Australis is a small constellation bordered by Sagittarius to the north, Scorpius to the west, Telescopium to the south, and Ara to the southwest. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is CrA, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of four segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 17h 58. 3m and 19h 19. 0m, while the coordinates are between −36. 77° and −45. 52°. Covering 128 square degrees, Corona Australis culminates at midnight around the 30th of June, while not a bright constellation, Corona Australis is nonetheless distinctive due to its easily identifiable pattern of stars, which has been described as horseshoe- or oval-shaped. Though it has no stars brighter than 4th magnitude, it still has 21 stars visible to the unaided eye. Nicolas Louis de Lacaille used the Greek letters Alpha through to Lambda to label the most prominent eleven stars in the constellation, the only star in the constellation to have received a name is Alfecca Meridiana or Alpha CrA. The name combines the Arabic name of the constellation with the Latin for southern, in Arabic, Alfecca means break, and refers to the shape of both Corona Australis and Corona Borealis. Also called simply Meridiana, it is a main sequence star located 130 light years away from Earth, with an apparent magnitude of 4.10. A rapidly rotating star, it spins at almost 200 km per second at its equator, like the star Vega, it has excess infrared radiation, which indicates it may be ringed by a disk of dust. It is currently a star, but will eventually evolve into a white dwarf, currently, it has a luminosity 31 times greater
Corona Australis
–
The constellation Corona Australis as it can be seen by the naked eye.
Corona Australis
–
List of stars in Corona Australis
Corona Australis
Corona Australis
–
Corona Australis depicted in the
Atlas Coelestis of
John Flamsteed
74.
Corvus (constellation)
–
Corvus is a small constellation in the Southern Celestial Hemisphere. Its name means raven in Latin, one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it depicts a raven, a bird associated with stories about the god Apollo, perched on the back of Hydra the water snake. The four brightest stars, Gamma, Delta, Epsilon, and Beta Corvi, with an apparent magnitude of 2.59, Gamma Corvi—also known as Gienah—is the brightest star in the constellation. It is a blue giant around four times as massive as the Sun. The young star Eta Corvi has been found to have two debris disks, three star systems have exoplanets, and a fourth planetary system is unconfirmed. TV Corvi is a dwarf nova—a white dwarf and brown dwarf in very close orbit, in the Babylonian star catalogues dating from at least 1100 BCE, what later became known as Corvus was called the Babylonian Raven. As with more familiar Classical astronomy, it was placed sitting on the tail of the Serpent, the Babylonian constellation was sacred to Adad, the god of rain and storm, in the second Millennium it would have risen just before the autumnal rainy season. John H. Rogers observed that Hydra signified Ningishzida, the god of the underworld in the Babylonian compendium MUL. APIN and he proposed that Corvus and Crater were death symbols and marked the gate to the underworld. These two constellations, along with the eagle Aquila and the fish Piscis Austrinus, were introduced to the Greeks around 500 BCE, furthermore, Hydra had been a landmark as it had straddled the celestial equator in antiquity. Corvus and Crater also featured in the iconography of Mithraism, which is thought to have been of middle-eastern origin before spreading into Ancient Greece, Corvus is associated with the myth of Apollo and his lover Coronis the Lapith. Coronis had been unfaithful to Apollo, when he learned this information from a white crow. Another legend associated with Corvus is that a crow stopped on his way to water for Apollo. Instead of telling the truth to Apollo, he lied and said that a snake, Hydra, kept him from the water, Apollo, realising this was a lie, flung the crow, cup, and snake into the sky. He further punished the wayward bird by ensuring it would forever be thirsty, in Chinese astronomy, the stars of Corvus are located within the Vermilion Bird of the South. The four main stars depict a chariot, Zhen, which is the 28th and final lunar mansion, Alpha and Eta mark the linchpins for the wheels, and Zeta is Changsha, a coffin. In Indian astronomy, the five stars of Corvus represent a hand or fist corresponding to the Hastā. Corvus was recognized as a constellation by several Polynesian cultures, in the Marquesas Islands, it was called Mee, in Pukapuka, it was called Te Manu, and in the Society Islands, it was called Metua-ai-papa. To Torres Strait Islanders, Corvus was the hand of the huge constellation Tagai
Corvus (constellation)
–
Corvus,
Crater, and other constellations seen around
Hydra in
Urania's Mirror (1825).
Corvus (constellation)
–
List of stars in Corvus
Corvus (constellation)
–
The constellation Corvus as it can be seen by the naked eye.
75.
Dorado
–
Dorado is a constellation in the southern sky. It was named in the late 16th century and is now one of the 88 modern constellations and its name refers to the dolphinfish, which is known as dorado in Portuguese, although it has also been depicted as a swordfish. Dorado contains most of the Large Magellanic Cloud, the remainder being in the constellation Mensa, the South Ecliptic pole also lies within this constellation. Its first depiction in an atlas was in Johann Bayers Uranometria of 1603 where it was also named Dorado. Dorado has been represented historically as a dolphinfish and a swordfish and it has also been represented as a goldfish. The constellation was known in the 17th and 18th century as Xiphias. The name Dorado ultimately become dominant and was adopted by the IAU, alpha Doradus is a blue-white star of magnitude 3.3,176 light-years from Earth. It is the brightest star in Dorado, Beta Doradus is a notably bright Cepheid variable star. It is a supergiant star that has a minimum magnitude of 4.1. One thousand and forty light-years from Earth, Beta Doradus has a period of 9 days and 20 hours, R Doradus is one of the many variable stars in Dorado. S Dor,9.721 hypergiant in the Large Magellanic Cloud, is the prototype of S Doradus variable stars, the variable star R Doradus 5.73 has the largest known apparent size of any star other than the Sun. Gamma Doradus is the prototype of the Gamma Doradus variable stars, supernova 1987A was the closest supernova to occur since the invention of the telescope. SNR 0509-67.5 is the remnant of an unusually energetic Type 1a supernova from about 400 years ago, HE 0437-5439 is a hypervelocity star escaping from the Milky Way/Magellanic Cloud system. Dorado is also the location of the South Ecliptic pole, which lies near the fishs head, the pole was called Polus Doradinalis by Willem Jansson Blaeu. Because Dorado contains part of the Large Magellanic Cloud, it is rich in deep sky objects, the Large Magellanic Cloud,1,000 light-years in diameter, is a satellite galaxy of the Milky Way Galaxy, located at a distance of 179,000 light-years. It has been deformed by its interactions with the larger Milky Way. In 1987, it became host to SN 1987A, the first supernova of 1987 and this 25, 000-light-year-wide galaxy contains over 10,000 million stars. All coordinates given are for Epoch J2000.0, NGC1566 is a face-on spiral galaxy
Dorado
–
The constellation Dorado as it can be seen by the naked eye.
Dorado
–
List of stars in Dorado
Dorado
–
NGC 1566 is an intermediate spiral galaxy.
Dorado
–
LEDA 89996 is a classic example of a spiral galaxy.
76.
Gemini (constellation)
–
Gemini is one of the constellations of the zodiac. It was one of the 48 constellations described by the 2nd century AD astronomer Ptolemy and its name is Latin for twins, and it is associated with the twins Castor and Pollux in Greek mythology. Gemini lies between Taurus to the west and Cancer to the east, with Auriga and Lynx to the north and Monoceros, the Sun resides in the astrological sign of Gemini from June 20 to July 20 each year. By mid August, Gemini will appear along the horizon in the morning sky prior to sunrise. The best time to observe Gemini at night is overhead during the months of January and February, by April and May, the constellation will be visible soon after sunset in the west. The easiest way to locate the constellation is to find its two brightest stars Castor and Pollux eastward from the familiar “V” shaped asterism of Taurus and the three stars of Orion’s belt. Another way is to draw a line from the Pleiades star cluster located in Taurus. In doing so, you are drawing a line that is relatively close to the ecliptic. The constellation contains 85 stars visible to observation on Earth without a telescope, the brightest star in Gemini is Pollux, and the second brightest is Castor. Castors Bayer designation as Alpha is attributable to a mistake by Johann Bayer, α Gem is a sextuple star system 52 light-years from Earth, which appears as a magnitude 1.6 blue-white star to the unaided eye. Two spectroscopic binaries are visible at magnitudes 1.9 and 3.0 with a period of 470 years. A wide-set red dwarf star is also a part of the system, β Gem is an orange-hued giant star of magnitude 1.2,34 light-years from Earth. Pollux has an extrasolar planet revolving around it, as do two other stars in Gemini, HD50554, and HD59686, γ Gem is a blue-white hued star of magnitude 1.9,105 light-years from earth. δ Gem is a binary star 59 light-years from Earth. The primary is a star of magnitude 3.5. The period is over 1000 years, it is divisible in amateur telescopes. ε Gem, a star, includes a primary yellow supergiant of magnitude 3.1,900 light-years from Earth. The optical companion, of magnitude 9.2, is visible in binoculars and small telescopes
Gemini (constellation)
–
The constellation Gemini as it can be seen with the unaided eye, with added connecting lines.
Gemini (constellation)
–
List of stars in Gemini
Gemini (constellation)
–
The star at the heart of the
Medusa Nebula made its final transition into retirement.
Gemini (constellation)
–
Gemini as depicted in
Urania's Mirror, a set of constellation cards published in London c.1825.
77.
Grus (constellation)
–
Grus is a constellation in the southern sky. Its name is Latin for the crane, a type of bird and it is one of twelve constellations conceived by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Grus first appeared on a 35-cm diameter celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayers star atlas Uranometria of 1603, the constellations Grus, Pavo, Phoenix and Tucana are collectively known as the Southern Birds. The constellations brightest star, Alpha Gruis, is known as Alnair. Beta Gruis is a red giant variable star with a magnitude of 2.3. Six star systems have found to have planets, the red dwarf Gliese 832 is one of the closest stars to Earth to have a planetary system. Another—WASP-95—has a planet that orbits every two days, deep-sky objects found in Grus include the planetary nebula IC5148, also known as the Spare Tyre Nebula, and a group of four interacting galaxies known as the Grus Quartet. The stars that form Grus were originally considered part of the neighbouring constellation Piscis Austrinus, Grus first appeared on a 35-cm diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius. Its first depiction in an atlas was in the German cartographer Johann Bayers Uranometria of 1603. De Houtman included it in his star catalogue the same year under the Dutch name Den Reygher, The Heron. Astronomer Ian Ridpath has reported the symbolism likely came from Plancius originally, Grus and the nearby constellations Phoenix, Tucana and Pavo are collectively called the Southern Birds. The stars that correspond to Grus were generally too far south to be seen from China, in Chinese astronomy, Gamma and Lambda Gruis may have been included in the tub-shaped asterism Bàijiù, along with stars from Piscis Austrinus. Alpha and Beta Gruis, along with Fomalhaut, Alpha Pavonis, Grus is bordered by Piscis Austrinus to the north, Sculptor to the northeast, Phoenix to the east, Tucana to the south, Indus to the southwest, and Microscopium to the west. Bayer straightened the tail of Piscis Austrinus to make way for Grus in his Uranometria, covering 366 square degrees, it ranks 45th of the 88 modern constellations in size and covers 0. 887% of the night sky. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Gru, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined as a polygon of 6 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 21h 27. 4m and 23h 27. 1m, while the coordinates are between −36. 31° and −56. 39°. Keyser and de Houtman assigned twelve stars to the constellation, Bayer depicted Grus on his chart, but did not assign its stars Bayer designations. French explorer and astronomer Nicolas Louis de Lacaille labelled them Alpha to Phi in 1756 with some omissions, in 1879, American astronomer Benjamin Gould added Kappa, Nu, Omicron and Xi, which had all been catalogued by Lacaille but not given Bayer designations
Grus (constellation)
–
The constellations Grus and
Piscis Austrinus, which once formed a single constellation, as depicted in Atlas Coelestis by
Johann Doppelmayr, ca. 1742
Grus (constellation)
–
List of stars in Grus
Grus (constellation)
–
The "southern birds", as depicted in
Johann Bayer 's
Uranometria
Grus (constellation)
–
The constellation Grus as it can be seen by the naked eye
78.
Horologium (constellation)
–
Horologium is a faint constellation in the southern sky. It was devised by French astronomer Nicolas Louis de Lacaille in 1752, the constellations brightest star is Alpha Horologii, an orange giant. R Horologii is a red giant Mira variable with one of the widest ranges in brightness known, three star systems have exoplanets, while Nu Horologii has a debris disk. He devised fourteen new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe, all but one honoured instruments that symbolised the Age of Enlightenment. Lacaille Latinised the name to Horologium on his 1763 chart, covering a total of 248.9 square degrees or 0. 603% of the sky, Horologium ranks 58th in area out of the 88 modern constellations. Its position in the Southern Celestial Hemisphere means that the constellation is visible to observers south of 23°N. Horologium is bordered by five different constellations, Eridanus, Caelum, Reticulum, Dorado, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Hor. The official constellation boundaries are defined by a twenty-two sided polygon, in the equatorial coordinate system, the right ascension coordinates of these borders lie between 02h 12. 5m and 04h 20. 2m, while the declination coordinates are between −39. 63° and −67. 04°. Horologium has only one star brighter than apparent magnitude 4, and 41 stars brighter than or equal to magnitude 6.5, Lacaille charted and designated 11 stars with the Bayer designations Alpha through to Lambda Horologii in 1756. Baily removed the designations of Epsilon and Theta Horologii as he held they were too faint to warrant naming and he was unable to find a star that corresponded to the coordinates Lacailles Beta Horologii. Determining that the coordinates were wrong, he assigned the designation to another star, kappa Horologii, too, was unable to be verified, yet was most likely the star HD18292. Gould assigned designations to what became Mu and Nu Horologii as he felt they were enough to warrant them. Alpha Horologii, the brightest, is a giant of magnitude 3.9. Bode depicted it as the pendulum, while Lacaille made it one of the weights. Beta Horologii is a giant of magnitude 5.0,314 light-years from Earth. Lambda Horologii is an ageing giant star of spectral type F2III that spins around at 140 km/second. It is 161 ±1 light-years from Earth, however, Horologium does have several variable stars. R Horologii is a red giant Mira variable with one of the widest ranges in brightness known and it has a minimum magnitude of 14.3 and a maximum magnitude of 4.7, its period is approximately 13 months
Horologium (constellation)
–
The constellation Horologium as it can be seen by the
naked eye.
Horologium (constellation)
–
List of stars in Horologium
79.
Hydrus
–
Hydrus /ˈhaɪdrəs/ is a small constellation in the deep southern sky. The first depiction of this constellation in an atlas was in Johann Bayers Uranometria of 1603. The French explorer and astronomer Nicolas Louis de Lacaille charted the brighter stars and its name means male water snake, as opposed to Hydra, a much larger constellation that represents a female water snake. It remains below the horizon for most Northern Hemisphere observers, the brightest star is the 2. 8-magnitude Beta Hydri, also the closest reasonably bright star to the south celestial pole. Pulsating between magnitude 3.26 and 3.33, Gamma Hydri is a red giant 60 times the diameter of our Sun. Lying near it is VW Hydri, one of the brightest dwarf novae in the heavens, four star systems in Hydrus have been found to have exoplanets to date, including HD10180, which could bear up to nine planetary companions. It first appeared on a 35-cm diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius, the first depiction of this constellation in a celestial atlas was in the German cartographer Johann Bayers Uranometria of 1603. The French explorer and astronomer Nicolas Louis de Lacaille called it l’Hydre Mâle on the 1756 version of his planisphere of the southern skies, distinguishing it from the feminine Hydra. The French name was retained by Jean Fortin in 1776 for his Atlas Céleste, covering 243 square degrees and 0. 589% of the night sky, it ranks 61st of the 88 constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Hyi, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 12 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 00h 06. 1m and 04h 35. 1m, while the coordinates are between −57. 85° and −82. 06°. Indeed, Herman Melville mentions it and Argo Navis in Moby Dick beneath effulgent Antarctic Skies, a line drawn between the long axis of the Southern Cross to Beta Hydri and then extended 4.5 times will mark a point due south. Hydrus culminates at midnight around 26 October, Lacaille charted and designated 20 stars with the Bayer designations Alpha through to Tau in 1756. Of these, he used the designations Eta, Pi and Tau twice each and he assigned Rho to a star that subsequent astronomers were unable to find. Beta Hydri, the brightest star in Hydrus, is a star of apparent magnitude 2.8. It has about 104% of the mass of the Sun and 181% of the Suns radius, the spectrum of this star matches a stellar classification of G2 IV, with the luminosity class of IV indicating this is a subgiant star. As such, it is a more evolved star than the Sun. It is the nearest subgiant star to the Sun and one of the oldest stars in the solar neighbourhood
Hydrus
–
Hydrus (lower right) in an extract from
Johann Bayer 's
Uranometria, its first appearance in a celestial atlas.
Hydrus
–
List of stars in Hydrus
Hydrus
–
The constellation Hydrus as it can be seen by the naked eye.
80.
Indus (constellation)
–
Indus is a constellation in the southern sky created in the late sixteenth century. Indus does not contain any bright stars, alpha Indi is the brightest star in Indus. It is a giant of magnitude 3.1,101 light-years from Earth. Beta Indi is a giant of magnitude 3.7,600 light-years from Earth. Delta Indi is a star of magnitude 4.4,185 light-years from Earth. Epsilon Indi is one of the closest stars to Earth, approximately 11.8 light years away and it is an orange dwarf of magnitude 4.7, meaning that the yellow dwarf Sun is slightly hotter and larger. The system has been discovered to contain a pair of brown dwarfs. Indus is home to one bright binary star, theta Indi is a binary star divisible in small amateur telescopes,97 light-years from Earth. Its primary is a star of magnitude 4.5. T Indi is the only bright variable star in Indus and it is a semi-regular, deeply coloured red giant with a period of 11 months,1900 light-years from Earth. Its minimum magnitude is 7 and its magnitude is 5. Galaxies include NGC7090 and NGC7049, all Sky Automated Survey for SuperNovae in 2015 detected a superluminous supernova, named ASASSN-15lh. The first depiction of this constellation in an atlas was in Johann Bayers Uranometria of 1603. Plancius portrayed the figure as a male with arrows in both hands but no bow. Ridpath, Ian, Tirion, Wil, Stars and Planets Guide, Princeton University Press, ISBN 0-691-08913-2 Ian Ridpath, Stars and Planets Guide, Collins, London. Media related to Indus at Wikimedia Commons Starry Night Photography, Indus Constellation Star Tales–Indus Indus Constellation at Constellation Guide
Indus (constellation)
–
The constellation Indus as it can be seen by the naked eye.
Indus (constellation)
–
List of stars in Indus
Indus (constellation)
–
Indus (top middle) in an extract from
Johann Bayer 's
Uranometria, its first appearance in a celestial atlas.
81.
Lupus (constellation)
–
Lupus /ˈljuːpəs/ is a constellation located in the deep southern sky. Its name is Latin for wolf, in ancient times, the constellation was considered an asterism within Centaurus, and was considered to have been an arbitrary animal, killed, or about to be killed, on behalf of, or for, Centaurus. An alternative visualization, attested by Eratosthenes, saw this constellation as a held by Centaurus. It was not separated from Centaurus until Hipparchus of Bithynia named it Therion in the 3rd century BC, no particular animal was associated with it until the Latin translation of Ptolemys work identified it with the wolf. The Greek constellation is based on the Babylonian figure known as the Mad Dog. This was a hybrid creature that combined the head and torso of a man with the legs. It is often found in association with the sun god and another mythical being called the Bison-man, Lupus is bordered by six different constellations, although one of them merely touches at the corner. The other five are Scorpius, Norma, Circinus, Libra, covering 333.7 square degrees and 0. 809% of the night sky, it ranks 46th of the 88 modern constellations. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Lup, the official constellation boundaries are defined by a twelve-sided polygon. The whole constellation is visible to observers south of latitude 34°N, overall, there are 127 stars within the constellations borders brighter than or equal to apparent magnitude 6.5. In his book Star Names and Their Meanings, R. H. Allen gave the names Yang Mun for Alpha Lupi, the brightest star in Lupus, and KeKwan for the blue giant Beta Lupi, both from Chinese. However, the first name is in error, both stars were part of a large Chinese constellation known in modern transliteration as Qíguān, the Imperial Guards, most of the brightest stars in Lupus are massive members of the nearest OB association, Scorpius-Centaurus. Alpha Lupi is a blue giant star of spectral type B1.5 III that is 460 ±10 light-years distant from Earth. It is a Beta Cephei variable, pulsating in brightness by 0.03 of a magnitude every 7 hours and 6 minutes, towards the north of the constellation are globular clusters NGC5824 and NGC5986, and close by the dark nebula B228. To the south are two clusters, NGC5822 and NGC5749, as well as globular cluster NGC5927 on the eastern border with Norma. On the western border are two spiral galaxies and the Wolf-Rayet planetary nebula IC4406, containing some of the hottest stars in existence, IC4406, also called the Retina Nebula, is a cylindrical nebula at a distance of 5,000 light-years. It has dust lanes throughout its center, another planetary nebula, NGC5882, is towards the center of the constellation. The transiting exoplanet Lupus-TR-3b lies in this constellation, the historic supernova SN1006 is described by various sources as appearing on April 30 to May 1,1006, in the constellation of Lupus
Lupus (constellation)
–
Lupus is located in the bottom-left corner of card 32 in
Urania's Mirror (1825)
Lupus (constellation)
–
List of stars in Lupus
Lupus (constellation)
–
The constellation Lupus as it can be seen by the
naked eye.
Lupus (constellation)
–
Planetary nebula NGC 5882. (Credit: HST/
NASA /
ESA).
82.
Lynx (constellation)
–
Lynx, named after the animal, is a constellation in the northern sky that was introduced in the 17th century by Johannes Hevelius. It is a faint constellation with its brightest stars forming a zigzag line, the orange giant Alpha Lyncis is the brightest star in the constellation, while the semiregular variable star Y Lyncis is a target for amateur astronomers. Six star systems have found to contain planets. Those of 6 Lyncis and HD75898 were discovered by the Doppler method, polish astronomer Johannes Hevelius formed the constellation in the 17th century from 19 faint stars that he observed with the unaided eye between the constellations Ursa Major and Auriga. Naming it Lynx because of its faintness, he challenged future stargazers to see it, Hevelius gave it the alternate name of Tiger in his catalogue as well, but kept the former name only in his atlas. English astronomer John Flamsteed adopted the constellation in his catalogue, published in 1712, Lynx is bordered by Camelopardalis to the north, Auriga to the west, Gemini to the southwest, Cancer to the south, Leo to the east and Ursa Major to the northeast. Covering 545.4 square degrees and 1. 322% of the sky, it ranks 28th of the 88 constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Lyn, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 20 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 06h 16m 13. 76s and 09h 42m 50. 22s, while the coordinates are between +32. 97° and +61. 96°. On dark nights, the stars can be seen as a crooked line extending roughly between Camelopardalis and Leo, and north of the bright star Castor. Lynx is most readily observed from the winter to late summer to northern hemisphere observers. The whole constellation is visible to observers north of latitude 28°S, english astronomer Francis Baily gave a single star a Bayer designation—Alpha Lyncis—while Flamsteed numbered 44 stars, though several lie across the boundary in Ursa Major. Overall, there are 97 stars within the constellations borders brighter than or equal to apparent magnitude 6.5, the brightest star in this constellation is Alpha Lyncis, with an apparent magnitude of 3.14. It is a giant of spectral type K7III located 203 ±2 light-years distant from Earth. Around twice as massive as the Sun, it has exhausted the hydrogen at its core and has evolved away from the main sequence, the star has swollen to about 55 times the Suns radius and it is emitting roughly 673 times the luminosity of the Sun. The stellar atmosphere has cooled, giving it a surface temperature of 3,880 K, the only star with a proper name is Alsciaukat, also known as 31 Lyncis, located 380 ±10 light-years from Earth. This star is also a giant with around twice the Suns mass that has swollen. It is anywhere from 59 to 75 times as wide as the Sun, Alsciaukat is also a variable star, ranging in brightness by 0.05 magnitude over 25 to 30 days from its baseline magnitude of 4.25
Lynx (constellation)
–
Illustration from
Urania's Mirror (1825). The obsolete constellation
Telescopium Herschelii is to its right.
Lynx (constellation)
–
List of stars in Lynx
83.
Lyra
–
It is one of 48 listed by the 2nd century astronomer Ptolemy, and is one of the 88 constellations recognized by the International Astronomical Union. Lyra was often represented on maps as a vulture or an eagle carrying a lyre. Beginning at the north, Lyra is bordered by Draco, Hercules, Vulpecula, Lyra is visible from the northern hemisphere from spring through autumn, and nearly overhead, in temperate latitudes, during the summer months. From the southern hemisphere, it is low in the northern sky during the winter months. Vega, Lyras brightest star is one of the brightest stars in the night sky, Beta Lyrae is the prototype of a class of stars known as Beta Lyrae variables. These binary stars are so close to other that they become egg-shaped. Epsilon Lyrae, known informally as the Double Double, is a multiple star system. Lyra also hosts the Ring Nebula, the second-discovered and best-known planetary nebula, in Greek mythology, Lyra represents the lyre of Orpheus. Made by Hermes from a shell, given to Apollo as a bargain. Orpheuss music was said to be so great that even objects such as trees, streams. Joining Jason and the Argonauts, his music was able to quell the voices of the dangerous Sirens, at one point, Orpheus married Eurydice, a nymph. While fleeing from an attack by Aristaeus, she stepped on a snake that bit her, to reclaim her, Orpheus entered the Underworld, where the music from his lyre charmed Hades. Hades relented and let Orpheus bring Eurydice back, on the condition that he never look back until outside. Unfortunately, near the end, Orpheus faltered and looked back. Orpheus spent the rest of his life strumming his lyre while wandering aimlessly through the land, there are two competing myths relating to the death of Orpheus. According to Eratosthenes, Orpheus failed to make a sacrifice to Dionysus due to his regard for Apollo as the supreme deity instead. Dionysus then sent his followers to rip Orpheus apart, ovid tells a rather different story, saying that women, in retribution for Orpheuss rejection of marriage offers, ganged up and threw stones and spears. At first, his music charmed them as well, but eventually their numbers and clamor overwhelmed his music, both myths then state that his lyre was placed in the sky by the muses
Lyra
–
Lyra can be seen on the right of this c. 1825 star map from
Urania's Mirror.
Lyra
–
List of stars in Lyra
Lyra
–
The constellation Lyra as it can be seen by the naked eye.
Lyra
–
A long-exposure image of Lyra
84.
Monoceros
–
Monoceros is a faint constellation on the celestial equator. Its name is Greek for unicorn and its definition is attributed to the 17th-century Dutch cartographer Petrus Plancius. It is bordered by Orion to the west, Gemini to the north, Canis Major to the south, other bordering constellations include Canis Minor, Lepus and Puppis. Monoceros is not easily seen with the eye, containing only a few fourth magnitude stars. Alpha Monocerotis has a magnitude of 3.93, slightly brighter than Gamma Monocerotis at 3.98. Beta Monocerotis is a star system, the three stars forming a triangle which seems to be fixed. The visual magnitudes of the stars are 4.7,5.2 and 6.1, William Herschel discovered it in 1781 and commented that it is one of the most beautiful sights in the heavens. Epsilon Monocerotis is a binary, with visual magnitudes of 4.5 and 6.5. S Monocerotis, or 15 Monocerotis, is a bluish white variable star and is located at the center of NGC2264, the variation in its magnitude is slight. It has a star of visual magnitude 8. V838 Monocerotis, a red supergiant star, had an outburst starting on January 6,2002, in February of that year. After the outburst was over, the Hubble Space Telescope was able to observe a light echo, Monoceros also contains Plasketts Star, which is a massive binary system whose combined mass is estimated to be that of almost 100 Suns put together. Monoceros contains two super-Earth exoplanets in one system, COROT-7b was detected by the COROT satellite and COROT-7c was detected by HARPS from ground-based telescopes. Until the announcement of Kepler-10b in January 2011, COROT-7b was the smallest exoplanet to have its diameter measured, both planets in this system were discovered in 2009. Monoceros contains many clusters and nebulae, most notable among them, M50 and it has an overall magnitude of 6.0 and is 4900 light-years from Earth. The Rosette Nebula, over 100 light-years in diameter, has a star cluster. It was independently discovered in the 1880s by Lewis Swift and Edward Emerson Barnard as they hunted for comets, the Christmas Tree Cluster is another open cluster in Monoceros. Named for its resemblance to a Christmas tree, it is bright at an overall magnitude of 3.9
Monoceros
–
The constellation Monoceros as it can be seen by the naked eye.
Monoceros
–
List of stars in Monoceros
Monoceros
–
The constellation Monoceros, from
Urania's Mirror, a set of star charts from 1825. Includes
Canis Minor and the obsolete constellation
Atelier Typographique
85.
Musca
–
Musca is a small constellation in the deep southern sky. The first depiction of this constellation in an atlas was in Johann Bayers Uranometria of 1603. It was also known as Apis for two hundred years, Musca remains below the horizon for most Northern Hemisphere observers. Two further star systems have found to have planets. The constellation also contains two Cepheid variables visible to the naked eye, theta Muscae is a triple star system, the brightest member of which is a Wolf–Rayet star. De Houtman included it in his star catalogue in 1598 under the Dutch name De Vlieghe, The Fly. They assigned four stars to the constellation, with a star that would be designated as Beta Muscae marking the head, Gamma the body. It first appeared on a 35-cm diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius, a 1603 celestial globe by Willem Blaeu depicts it as providing nourishment for the nearby constellation Chamaeleon—its tongue trying to catch the insect. The French explorer and astronomer Nicolas Louis de Lacaille called it la Mouche on the 1756 version of his planisphere of the southern skies, jean Fortin retained the French name in 1776 for his Atlas Céleste, while Lacaille Latinised the name for his revised Coelum Australe Stelliferum in 1763. Today the name is simply Musca and it is the only official constellation depicting an insect. The Kalapalo people of Mato Grosso state in Brazil called Alpha, the stars of Musca, along with Fomalhaut, Alpha Pavonis, and Alpha and Beta Gruis were all claimed by the Arrernte. Musca is bordered by Crux to the north, Carina to the west, Chamaeleon to the south, Apus and Circinus to the east, covering 138 square degrees and 0. 335% of the night sky, it ranks 77th of the 88 constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Mus, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of six segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 11h 19. 3m and 13h 51. 1m, while the coordinates are between −64. 64° and −75. 68°. The whole constellation is visible to observers south of latitude 14°N, Lacaille charted and designated ten stars with the Bayer designations Alpha through to Kappa in 1756. He catalogued stars that became Lambda and Mu but did not designate them as he considered them informes as they lay outside the asterism proper, Baily considered them part of Musca, and Gould gave them their Bayer designations. Francis Baily also dropped Kappa, which he felt was too faint to warrant a name and these last two stars are 1° apart, quite far to be sharing a Bayer designation. Lacaille had originally labelled the fainter one as Zeta, while Baily presupposed hed meant to label the brighter one, reluctant to remove Lacailles designation, he gave them both the Zeta designation
Musca
–
Musca (as Apis) can be seen in the upper right of this extract from Bayer's
Uranometria of 1603
Musca
–
List of stars in Musca
Musca
–
The constellation Musca as it can be seen by the naked eye
Musca
–
The
Coalsack Nebula can be seen as the large dark region near the top of the photo. It extends into the northeast of Musca. The vertical dark column in the lower right of the image is the
Dark Doodad Nebula.
86.
Norma (constellation)
–
Its name is Latin for normal, referring to a right angle, and is variously considered to represent a rule, a carpenters square, a set square or a level. It remains one of the 88 modern constellations Four of Normas brighter stars—Gamma, Delta, Epsilon, Gamma2 Normae is the brightest star with an apparent magnitude of 4.0. Mu Normae is one of the most luminous stars known, with a luminosity half- to one million times that of the Sun, Four star systems are known to harbour planets. The Milky Way passes through Norma, and the constellation contains eight open clusters visible to observers with binoculars, the constellation also hosts Abell 3627, also called the Norma Cluster, one of the most massive galaxy clusters known. He devised 14 new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe, all but one honored instruments that symbolised the Age of Enlightenment. The level was dangling from the apex of a triangle, leading astronomers to conclude he was renaming l’Equerre et la Regle to le Niveau the level. In any case, the name had been shortened and Latinised by Lacaille to Norma by 1763. Norma is bordered by Scorpius to the north, Lupus to the northwest, Circinus to the west, Triangulum Australe to the south, covering 165.3 square degrees and 0. 401% of the night sky, it ranks 74th of the 88 constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Nor, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of ten segments. The whole constellation is visible to observers south of latitude 29°N, though Beta Normae was depicted on his star chart, it was inadvertently left out of Lacailles 1763 catalogue, was likewise transferred to Scorpio by Baily and named H Scorpii by Gould. Normas brightest star, Gamma2 Normae, is only of magnitude 4.0, overall, there are 44 stars within the constellations borders brighter than or equal to apparent magnitude 6.5. The four main stars—Gamma, Delta, Epsilon and Eta—make up a square in this region of faint stars, Gamma1 and Gamma2 Normae are an optical double, and not a true binary star system. Located 129 ±1 light-years away from Earth, Gamma2 Normae is a giant of spectral type G8III around 2 to 2.5 times as massive as the Sun. It has swollen to a diameter 10 times that of the Sun and it also is half of a close optical double, with a magnitude 10 companion star related by line of sight only. Gamma1 Normae is a supergiant, located much further away at around 1500 light-years from Earth. Epsilon Normae is a binary, with two blue-white main sequence stars of almost equal mass and spectral type orbiting each other every 3.26 days. There is a third star separated by 22 arcseconds, which has a magnitude of 7.5 and is likely a smaller B-type main sequence star of spectral type B9V. The system is 530 ±20 light-years distant from Earth, Eta Normae is a giant of spectral type G8III with an apparent magnitude of 4.65
Norma (constellation)
–
The constellation Norma as it can be seen by the naked eye
Norma (constellation)
–
List of stars in Norma
Norma (constellation)
–
The Ant Nebula, Mz 3, viewed with the Hubble Space Telescope
Norma (constellation)
–
Galaxies of the
Norma Cluster (yellow) in a 0.5° x 0.5° field
87.
Orion (constellation)
–
Orion is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous and recognizable constellations in the night sky and it was named after Orion, a hunter in Greek mythology. Its brightest stars are Rigel and Betelgeuse, a blue-white and a red supergiant, the earliest depiction that has been linked to the constellation of Orion is a prehistoric mammoth ivory carving found in a cave in the Ach valley in West Germany in 1979. Archaeologists have estimated it to have been fashioned approximately 32,000 to 38,000 years ago, the distinctive pattern of Orion has been recognized in numerous cultures around the world, and many myths have been associated with it. It has also used as a symbol in the modern world. The Babylonian star catalogues of the Late Bronze Age name Orion MULSIPA. ZI. AN. NA, the Babylonian constellation was sacred to Papshukal and Ninshubur, both minor gods fulfilling the role of messenger to the gods. In ancient Egypt, the stars of Orion were regarded as a god, because Orion rises before Sirius, the star whose heliacal rising was the basis for the Solar Egyptian calendar, Sah was closely linked with Sopdet, the goddess who personified Sirius. The god Sopdu was said to be the son of Sah, Sah was syncretized with Osiris, while Sopdet was syncretized with Osiris mythological wife, Isis. In the Pyramid Texts, from the 24th and 23rd centuries BC, the Armenians identified their legendary patriarch and founder Hayk with Orion. Hayk is also the name of the Orion constellation in the Armenian translation of the Bible, the Bible mentions Orion three times, naming it Kesil. e. Job 9,9, Job 38,31, and Amos 5,8, in ancient Aram, the constellation was known as Nephîlā′, the Nephilim may have been Orions descendants. One myth recounts Gaias rage at Orion, who dared to say that he would kill every animal on the planet, the angry goddess tried to dispatch Orion with a scorpion. This is given as the reason that the constellations of Scorpius, however, Ophiuchus, the Serpent Bearer, revived Orion with an antidote. This is said to be the reason that the constellation of Ophiuchus stands midway between the Scorpion and the Hunter in the sky. The constellation is mentioned in Horaces Odes, Homers Odyssey and Iliad, and Virgils Aeneid In medieval Muslim astronomy, Orion was known as al-jabbar, Orions sixth brightest star, Saiph, is named from the Arabic, saif al-jabbar, meaning sword of the giant. In China, Orion was one of the 28 lunar mansions Sieu （宿） and it is known as Shen （參）, literally meaning three, for the stars of Orions Belt. The Rig Veda refers to the Orion Constellation as Mriga, the Mriga means Deer, locally known as Harnu in folk parlance. There are many folk songs narrating the Harnu, the Malay called Orion Belt Bintang Tiga Beradik
Orion (constellation)
–
Click on to see large image
Orion (constellation)
–
List of stars in Orion
Orion (constellation)
–
Star formation in the constellation Orion as photographed in
infrared by
NASA 's
Spitzer Space Telescope
Orion (constellation)
–
Orion in the 9th century
Leiden Aratea
88.
Pegasus (constellation)
–
Pegasus is a constellation in the northern sky, named after the winged horse Pegasus in Greek mythology. It was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, with an apparent magnitude varying between 2.37 and 2.45, the brightest star in Pegasus is the orange supergiant Epsilon Pegasi, also known as Enif, which marks the horses muzzle. Alpha, Beta, and Gamma, together with Alpha Andromedae form the asterism known as the Square of Pegasus. Twelve star systems have found to have exoplanets. 51 Pegasi was the first Sun-like star discovered to have an exoplanet companion, the Babylonian constellation IKU had four stars of which three were later part of the Greek constellation Hippos. Pegasus, in Greek mythology, was a horse with magical powers. One myth regarding his powers says that his hooves dug out a spring, Hippocrene, Pegasus was the one who delivered Medusas head to Polydectes, after which he travelled to Mount Olympus in order to be the bearer of thunder and lightning for Zeus. Eventually, he became the horse to Bellerophon, who was asked to kill the Chimera and succeeded with the help of Athena, despite this success, after the death of his children, Bellerophon asked Pegasus to take him to Mount Olympus. Though Pegasus agreed, he plummeted back to Earth after Zeus either threw a thunderbolt at him or made Pegasus buck him off. In ancient Persia, Pegasus was depicted by al-Sufi as a horse facing east, unlike most other uranographers. In al-Sufis depiction, Pegasuss head is made up of the stars of Lacerta the lizard and its right foreleg is represented by β Peg and its left foreleg is represented by η Peg, μ Peg, and λ Peg, its hind legs are marked by 9 Peg. The back is represented by π Peg and μ Cyg, in Chinese astronomy, the modern constellation of Pegasus lies in The Black Tortoise of the north, where the stars were classified in several separate asterisms of stars. Epsilon and Theta Pegasi are joined with Alpha Aquarii to form Wei 危 rooftop, in Hindu astronomy, the Great Square of Pegasus contained the 26th and 27th lunar mansions. More specifically, it represented a bedstead that was a place for the Moon. Covering 1121 square degrees, Pegasus is the seventh-largest of the 88 constellations, the three-letter abbreviation for the constellation, as adopted by the IAU in 1922, is Peg. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined as a polygon of 35 segments. In the equatorial system the right ascension coordinates of these borders lie between 21h 12. 6m and 00h 14. 6m, while the declination coordinates are between 2. 33° and 36. 61°. Its position in the Northern Celestial Hemisphere means that the constellation is visible to observers north of 53°S
Pegasus (constellation)
–
Pegasus with the foal
Equuleus next to it, as depicted in
Urania's Mirror, a set of constellation cards published in London c.1825. The horses appear upside-down in relation to the constellations around them.
Pegasus (constellation)
–
List of stars in Pegasus
Pegasus (constellation)
–
The constellation Pegasus as it can be seen by the naked eye.
89.
Phoenix (constellation)
–
Phoenix is a minor constellation in the southern sky. Named after the phoenix, it was first depicted on a celestial atlas by Johann Bayer in his 1603 Uranometria. The French explorer and astronomer Nicolas Louis de Lacaille charted the brighter stars, the constellation stretches from roughly −39° to −57° declination, and from 23. 5h to 2. 5h of right ascension. The constellations Phoenix, Grus, Pavo and Tucana, are known as the Southern Birds, the brightest star, Alpha Phoenicis, is named Ankaa, an Arabic word meaning the Phoenix. It is a giant of apparent magnitude 2.4. Next is Beta Phoenicis, actually a system composed of two yellow giants with a combined apparent magnitude of 3.3. Phoenix is the radiant of two meteor showers, the Phoenicids in December, and the July Phoenicids. Phoenix was the largest of the twelve constellations established by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and it first appeared on a 35-cm diameter celestial globe published in 1597 in Amsterdam by Plancius with Jodocus Hondius. The first depiction of this constellation in an atlas was in Johann Bayers Uranometria of 1603. De Houtman included it in his star catalog the same year under the Dutch name Den voghel Fenicx, The Bird Phoenix. One name of the brightest star Alpha Phoenicis—Ankaa—is derived from the Arabic العنقاء al-‘anqā’ the phoenix, in addition, the same group of stars was sometimes imagined by the Arabs as a boat, Al Zaurak, on the nearby river Eridanus. He observed, the introduction of a Phoenix into modern astronomy was, in a measure, the Chinese incorporated Phoenixs brightest star, Ankaa, and stars from the adjacent constellation Sculptor to depict Bakui, a net for catching birds. Phoenix and the constellation of Grus together were seen by Julius Schiller as portraying Aaron the High Priest. These two constellations, along with nearby Pavo and Tucana, are called the Southern Birds, the bright star Achernar is nearby. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Phe, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 10 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 23h 26. 5m and 02h 25. 0m, while the coordinates are between −39. 31° and −57. 84°. This means it remains below the horizon to anyone living north of the 40th parallel in the Northern Hemisphere and it is most visible from locations such as Australia and South Africa during late Southern Hemisphere spring. Most of the lies within, and can be located by, forming a triangle of the bright stars Achernar, Fomalhaut
Phoenix (constellation)
–
The constellation Phoenix as depicted in
Johann Gabriel Doppelmayr 's Atlas Coelestis, ca. 1742.
Phoenix (constellation)
–
List of stars in Phoenix
Phoenix (constellation)
–
The "southern birds", as depicted in
Johann Bayer 's
Uranometria. Phoenix is on the lower left.
Phoenix (constellation)
–
The constellation Phoenix as it can be seen by the naked eye.
90.
Puppis
–
Puppis /ˈpʌpᵻs/ is a constellation in the southern sky. Puppis is the largest of the three constellations in square degrees and it is one of the 88 modern constellations recognized by the International Astronomical Union. Argo Navis was sub-divided in 1752 by the French astronomer Nicolas Louis de Lacaille, despite the division, Lacaille kept Argos Bayer designations. Therefore Carina has the α, β and ε, Vela has γ and δ, Puppis has ζ, several extrasolar planet systems have been found around stars in the constellation Puppis, including, On July 1,2003, a planet was found orbiting the star HD70642. This planetary system is much like Jupiter with a wide, circular orbit, on May 17,2006, HD69830 was discovered to have three Neptune-mass planets, the first multi-planetary system without any Jupiter-like or Saturn-like planets. The star also hosts an asteroid belt at the region between middle planet to outer planet, on June 21,2007, the first extrasolar planet found in the open cluster NGC2423, was discovered around the red giant star NGC 2423-3. The planet is at least 10.6 times the mass of Jupiter, on September 22,2008, two Jupiter-like planets were discovered around HD60532. HD60532 b has a mass of 1.03 MJ and orbits at 0.759 AU. HD60532 c has a mass of 2.46 MJ and orbits at 1.58 AU. As the Milky Way runs through Puppis, there are a number of open clusters in the constellation. M46 and M47 are two clusters in the same binocular field. M47 can be seen with the eye under dark skies. Messier 93 is another open cluster somewhat to the south, NGC2451 is a very bright open cluster containing the star c Puppis and the near NGC2477 is a good target for small telescopes. The star Pi Puppis is the component of a bright group of stars known as Collinder 135. M46 is a open cluster with an overall magnitude of 6.1 at a distance of approximately 5400 light-years from Earth. The planetary nebula NGC2438 is superimposed, it is approximately 2900 light-years from Earth, m46 is classified as a Shapley class f and a Trumpler class III2 m cluster. This means that it is a cluster that appears distinct from the star field, however. The clusters stars, numbering between 50 and 100, have a range in brightness
Puppis
–
The constellation Puppis as it can be seen by the naked eye.
Puppis
–
List of stars in Puppis
Puppis
–
A cosmic concoction in
NGC 2467
91.
Pyxis
–
Pyxis is a small and faint constellation in the southern sky. Abbreviated from Pyxis Nautica, its name is Latin for a mariners compass, Pyxis was introduced by Nicolas Louis de Lacaille in the 18th century, and is counted among the 88 modern constellations. Pyxis is completely visible from south of 53 degrees north, with its best evening-sky visibility in February. The plane of the Milky Way passes through Pyxis, a faint constellation, its three brightest stars—Alpha, Beta and Gamma Pyxidis—are in a rough line. At magnitude 3.68, Alpha is the constellations brightest star and it is a blue-white star around 22,000 times as luminous as the Sun. Near Alpha is T Pyxidis, a recurrent nova that has flared up to magnitude 7 every few decades, three star systems have planets, all discovered by doppler spectroscopy. In ancient Chinese astronomy, Alpha, Beta and Gamma Pyxidis formed part of Tianmiao and he devised fourteen new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe. All but one honoured instruments that symbolised the Age of Enlightenment, Lacaille Latinised the name to Pixis Nautica on his 1763 chart. The Ancient Greeks identified the four stars of Pyxis as the mast of the great ship Argo Navis. Covering 220.8 square degrees and hence 0. 535% of the sky and its position in the Southern Celestial Hemisphere means that the whole constellation is visible to observers south of 52°N. It is most visible in the sky in February and March. A small constellation, it is bordered by Hydra to the north, Puppis to the west, Vela to the south, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Pyx. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of eight sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 8h 27. 7m and 9h 27. 6m, while the coordinates are between −17. 41° and −37. 29°. Lacaille gave Bayer designations to ten stars now named Alpha to Lambda Pyxidis, skipping the Greek letters iota, Pyxis is a faint constellation, its three brightest stars—Alpha, Beta and Gamma Pyxidis—form a rough line. Overall, there are 41 stars within the borders with apparent magnitudes brighter than or equal to 6.5. With an apparent magnitude of 3.68, Alpha Pyxidis is the brightest star in the constellation. Located 880 ±30 light-years distant from Earth, it is a giant star of spectral type B1. 5III that is around 22,000 times as luminous as the Sun and has 9.4 ±0.7 times its diameter
Pyxis
–
Pyxis can be seen overlying the mast of
Argo Navis
Pyxis
–
List of stars in Pyxis
Pyxis
–
Hubble Space Telescope picture of
T Pyxidis, showing ejected material from past eruptions
Pyxis
–
The planetary nebula NGC 2818, imaged by the Hubble telescope
92.
Scorpius
–
Scorpius is one of the constellations of the zodiac. Its name is Latin for scorpion, and its symbol is, Scorpius is one of the 48 constellations identified by the Greek astronomer Ptolemy in the second century. It is an ancient constellation that pre-dated the Greeks and it lies between Libra to the west and Sagittarius to the east. It is a constellation located in the southern hemisphere near the center of the Milky Way. Scorpius contains many stars, including Antares, rival of Mars, so named because of its distinct reddish hue, β1 Sco, a triple star, δ Sco, θ Sco, ν Sco, ξ Sco, π Sco, σ Sco. Marking the tip of the scorpions curved tail are λ Sco and υ Sco, given their proximity to one another, λ Sco and υ Sco are sometimes referred to as the Cats Eyes. The constellations bright stars form a pattern like a longshoremans hook, most of them are massive members of the nearest OB association, Scorpius-Centaurus. The star δ Sco, after having been a stable 2.3 magnitude star and it has since become a variable star fluctuating between 2.0 and 1.6. This means that at its brightest it is the second brightest star in Scorpius, U Scorpii is the fastest known nova with a period of about 10 years. ω¹ Scorpii and ω² Scorpii are a double, which can be resolved by the unaided eye. They have contrasting blue and yellow colours, the star once designated γ Sco is today known as σ Lib. The division into Libra was formalised during Roman times, Messier 80 is a globular cluster of magnitude 7.3,33,000 light-years from Earth. It is a compact Shapley class II cluster, the classification indicates that it is highly concentrated, m80 was discovered in 1781 by Charles Messier. It was the site of a discovery in 1860 when Arthur von Auwers discovered the nova T Scorpii. NGC6302, also called the Bug Nebula, is a planetary nebula. NGC6334, also known as the Cats Paw Nebula, is an emission nebula, in Greek mythology, the myths associated with Scorpio almost invariably also contain a reference to Orion. According to one of these myths it is written that Orion boasted to goddess Artemis and her mother, Leto, although Artemis was known to be a hunter herself she offered protection to all creatures. Artemis and her mother Leto sent a scorpion to deal with Orion, the pair battled and the scorpion killed Orion
Scorpius
–
The constellation Scorpius as it can be seen by naked eye (with constellation lines drawn in).
Scorpius
–
List of stars in Scorpius
Scorpius
–
Scorpius as depicted in
Urania's Mirror, a set of constellation cards published in London c.1825.
93.
Sculptor (constellation)
–
Sculptor is a small and faint constellation in the southern sky. It was introduced by Nicolas Louis de Lacaille in the 18th century and he originally named it Apparatus Sculptoris, but the name was later shortened. The region to the south of Cetus and Aquarius had been named by Aratus in 270 BCE as The Waters – an area of scattered faint stars with two brighter stars standing out, professor of astronomy Bradley Schaefer has proposed that these stars were most likely Alpha and Delta Sculptoris. He named all but one in honour of instruments that symbolised the Age of Enlightenment, Sculptor is a small constellation bordered by Aquarius and Cetus to the north, Fornax to the east, Phoenix to the south, Grus to the southwest, and Piscis Austrinus to the west. The bright star Fomalhaut is nearby, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Scl. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 6 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 23h 06. 4m and 01h 45. 5m, while the coordinates are between −24. 80° and −39. 37°. The whole constellation is visible to observers south of latitude 50°N, no stars brighter than 3rd magnitude are located in Sculptor. This is explained by the fact that Sculptor contains the south pole where stellar density is very low. Overall, there are 52 stars within the constellations borders brighter than or equal to apparent magnitude 6.5, the brightest star is Alpha Sculptoris, an SX Arietis-type variable star with a spectral type B7IIIp and an apparent magnitude of 4.3. It is 780 ±30 light-years distant from Earth, R Sculptoris is a red giant that has been found to be surrounded by spirals of matter likely ejected around 1800 years ago. The constellation also contains the Sculptor Dwarf, a galaxy which is a member of the Local Group, as well as the Sculptor Group. The Sculptor Galaxy, a spiral galaxy and the largest member of the group. Another prominent member of the group is the irregular galaxy NGC55, one unique galaxy in Sculptor is the Cartwheel Galaxy, at a distance of 500 million light-years. The result of a merger around 300 million years ago, the Cartwheel Galaxy has a core of older, yellow stars, and a ring of younger, blue stars. The smaller galaxy in the collision is now incorporated into the core, the shock waves from the collision sparked extensive star formation in the outer ring. Sculptor was a United States Navy Crater class cargo ship named after the constellation, notes Citations Sources Sculptor Constellation at Constellation Guide
Sculptor (constellation)
–
Curious spiral around red giant star
R Sculptoris.
Sculptor (constellation)
–
List of stars in Sculptor
94.
Scutum (constellation)
–
Scutum is a small constellation introduced in the seventeenth century. Its name is Latin for shield, later, the name was shortened to Scutum. Five bright stars of Scutum were previously known as 1,6,2,3, coincidentally, the Chinese also associated these stars with battle armor, incorporating them into the larger asterism known as Tien Pien, i. e. the Heavenly Casque. Scutum is not a bright constellation, with the brightest star, Alpha Scuti, but some stars are notable in the constellation. Beta Scuti is the second brightest at magnitude 4.22, beta Scuti is a binary system, with the primary with a spectral type similar to the Sun, although it is 1,270 times brighter. Delta Scuti is a white giant star, which is now coming at the direction of the Solar System. Within 1.3 million years it will come as close to 10 light years from Earth, UY Scuti is a red supergiant pulsating variable star. At 1,708 ±192 solar radii, it is the largest star currently known, although not a large constellation, Scutum contains several open clusters, as well as a globular cluster and a planetary nebula. The two best known deep sky objects in Scutum are M11 and the open cluster M26, the globular cluster NGC6712 and the planetary nebula IC1295 can be found in the eastern part of the constellation, only 24 arcminutes apart. The most prominent open cluster in Scutum is the Wild Duck Cluster and it was named by William Henry Smyth in 1844 for its resemblance in the eyepiece to a flock of ducks in flight. The cluster,6200 light-years from Earth and 20 light-years in diameter, contains approximately 3000 stars and it is 220 million years old. The space probe Pioneer 11 is moving in the direction of this constellation and it will not be nearing the closest star in this constellation for over a million years at present speed, by which time its batteries will be long dead. Taurus Poniatovii - a constellation created by the Polish astronomer Marcin Odlanicki Poczobutt in 1777 to honor King of Poland Stanisław August Poniatowski, stars and Planets Guide, Collins, London. The Deep Photographic Guide to the Constellations, Scutum Star Tales – Scutum Scutum Constellation at Constellation Guide
Scutum (constellation)
–
The constellation Scutum as it can be seen by the naked eye.
Scutum (constellation)
–
List of stars in Scutum
Scutum (constellation)
–
Serpens held by Ophiuchus, as depicted in
Urania's Mirror, a set of constellation cards published in London c. 1825. Above the tail of the serpent is the now-obsolete constellation
Taurus Poniatovii while below it is Scutum.
95.
Serpens
–
Serpens is a constellation of the northern hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy and it is unique among the modern constellations in being split into two non-contiguous parts, Serpens Caput to the west and Serpens Cauda to the east. Between these two lies the constellation of Ophiuchus, the Serpent-Bearer. In figurative representations, the body of the serpent is represented as passing behind Ophiuchus between Mu Serpentis in Serpens Caput and Nu Serpentis in Serpens Cauda. The brightest star in Serpens is the red giant star Alpha Serpentis, or Unukalhai, in Serpens Caput, also located in Serpens Caput are the naked-eye globular cluster Messier 5 and the naked-eye variables R Serpentis and Tau4 Serpentis. Part of the Milky Ways galactic plane passes through Serpens Cauda, the nebula measures 70 light-years by 50 light-years and contains the Pillars of Creation, three dust clouds that became famous for the image taken by the Hubble Space Telescope. In Greek mythology, Serpens represents a snake held by the healer Asclepius, represented in the sky by the constellation Ophiuchus, Asclepius once killed a snake, but the animal was subsequently resurrected after a second snake placed a revival herb on it before its death. As snakes shed their skin every year, they were known as the symbol of rebirth in ancient Greek society, although this is likely the logic for Serpens presence with Ophiuchus, the true reason is still not fully known. Sometimes, Serpens was depicted as coiling around Ophiuchus, but the majority of atlases showed Serpens passing either behind Ophiuchus body or between his legs. In some ancient atlases, the constellations Serpens and Ophiuchus were depicted as two separate constellations, although often they were shown as a single constellation. One notable figure to depict Serpens separately was Johann Bayer, thus, when Eugène Delporte established modern constellation boundaries in the 1920s, he elected to depict the two separately. However, this posed the problem of how to disentangle the two constellations, with Deporte deciding to split Serpens into two areas—the head and the tail—separated by the continuous Ophiuchus. These two areas known as Serpens Caput and Serpens Cauda, caput being the Latin word for head. In Chinese astronomy, most of the stars of Serpens represented part of a wall surrounding a marketplace, known as Tianshi, Serpens also contains a few Chinese constellations. Two stars in the tail represented part of Shilou, the tower with the market office, another star in the tail represented Liesi, jewel shops. One star in the head marked Tianru, the crown princes wet nurse, there were two serpent constellations in Babylonian astronomy, known as Mušḫuššu and Bašmu. It appears that Mušḫuššu was depicted as a hybrid of a dragon, a lion and a bird, Bašmu was a horned serpent and roughly corresponds to the Ὄφις constellation of Eudoxus of Cnidus on which the Ὄφις of Ptolemy is based. Serpens is the one of the 88 modern constellations to be split into two disconnected regions in the sky, Serpens Caput and Serpens Cauda
Serpens
–
Serpens held by Ophiuchus, as depicted in
Urania's Mirror, a set of constellation cards published in
London c. 1825. Above the tail of the serpent is the now-obsolete constellation
Taurus Poniatovii while below it is
Scutum
Serpens
–
List of stars in Serpens
Serpens
–
The constellation Serpens (Caput) as it can be seen by the naked eye
Serpens
–
The constellation Serpens (Cauda) as it can be seen by the naked eye
96.
Triangulum Australe
–
Triangulum Australe is a small constellation in the far Southern Celestial Hemisphere. Its name is Latin for the triangle, which distinguishes it from Triangulum in the northern sky and is derived from the almost equilateral pattern of its three brightest stars. It was first depicted on a globe as Triangulus Antarcticus by Petrus Plancius in 1589. The French explorer and astronomer Nicolas Louis de Lacaille charted and gave the stars their Bayer designations in 1756. Alpha Trianguli Australis, known as Atria, is an orange giant. Completing the triangle are the two main sequence stars Beta and Gamma Trianguli Australis. Although the constellation lies in the Milky Way and contains many stars, notable features include the open cluster NGC6025 and planetary nebula NGC5979. Italian navigator Amerigo Vespucci explored the New World at the beginning of the 16th century and he learnt to recognize the stars in the southern hemisphere and made a catalogue for his patron king Manuel I of Portugal, which is now lost. As well as the catalogue, Vespucci wrote descriptions of the southern stars and this was sent to his patron in Florence, Lorenzo di Pierfrancesco de Medici, and published as Mundus Novus in 1504. His student Petrus Keyzer, along with Dutch explorer Frederick de Houtman, Triangulum Australe was more accurately depicted in Johann Bayers celestial atlas Uranometria in 1603, where it was also given its current name. Also depicting it as a level, German Johann Bode gave it the alternate name of Libella in his Uranographia. German poet and author Philippus Caesius saw the three stars as representing the Three Patriarchs, Abraham, Isaac and Jacob. The Wardaman people of the Northern Territory in Australia perceived the stars of Triangulum Australe as the tail of the Rainbow Serpent, overhead in October, the Rainbow Serpent gives Lightning a nudge to bring on the wet season rains in November. Triangulum Australe is a constellation bordered by Norma to the north, Circinus to the west, Apus to the south. It lies near the Pointers, with only Circinus in between, the constellation is located within the Milky Way, and hence has many stars. A roughly equilateral triangle, it is easily identifiable, Triangulum Australe lies too far south in the celestial southern hemisphere to be visible from Europe, yet is circumpolar from most of the southern hemisphere. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is TrA, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 18 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 14h 56. 4m and 17h 13. 5m, while the coordinates are between −60. 26° and −70. 51°
Triangulum Australe
–
ESO 69-6, two merging galaxies with prominent long tails, photographed by the
Hubble Space Telescope
Triangulum Australe
–
List of stars in Triangulum Australe
97.
Vela (constellation)
–
Vela is a constellation in the southern sky. Its name is Latin for the sails of a ship, and it was part of a larger constellation, the ship Argo Navis. With an apparent magnitude of 1.8, its brightest star is the hot blue multiple star Gamma Velorum, Delta and Kappa Velorum, together with Epsilon and Iota Carinae, form the asterism known as the False Cross. 1. 95-magnitude Delta is actually a triple or quintuple star system, german cartographer Johann Bayer depicted the constellation on his Uranometria of 1603, and gave the stars Bayer designations from Alpha to Omega. However, his chart was inaccurate as the constellation was not visible from the Northern Hemisphere, Argo was more accurately charted and subdivided in 1752 by the French astronomer Nicolas Louis de Lacaille, forming Carina, Vela, and Puppis. Despite the division, Lacaille kept Argos Bayer designations, therefore, Carina has the Alpha, Beta and Epsilon, Vela has Gamma and Delta, Puppis has Zeta, and so on. Vela is bordered by Antlia and Pyxis to the north, Puppis to the northwest, Carina to the south and southwest, covering 500 square degrees, it ranks 32nd of the 88 modern constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Vel, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 14 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 08h 13. 3m and 11h 05. 5m, while the coordinates are between −37. 16° and −57. 17°. The brightest star in the constellation, Gamma Velorum, is a multiple star system. The brighter component, known as Gamma2 Velorum or Suhail, shines as a star of apparent magnitude 1.83. It is a spectroscopic binary made up of two hot blue stars orbiting each other every 78.5 days and separated by somewhere between 0.8 and 1.6 Astronomical Units. The second component is a rare example of hot star known as a Wolf–Rayet star. It has a temperature of 57,000 and is around 170,000 times as luminous as our sun. Gamma1 is a star of spectral type B2III and apparent magnitude 4.3. The two pairs are separated by 41 arcseconds, easily separable in binoculars, parallax measurements give a distance of 1,116 light years, meaning that they are at least 12,000 AU apart. Further afield are 7. 3-magnitude Gamma Velorum C and 9.4 magnitude Gamma Velorum D, the next brightest star is Delta Velorum, also a multiple star system and one of the brightest eclipsing binaries in the sky. Appearing as a star of magnitude 1.95, Delta is actually a triple or possibly quintuple star system located around 80 light-years from the Solar System
Vela (constellation)
–
Deep-sky photograph of
NGC 3132, also known as the Eight-Burst or Southern Ring Nebula. © NASA.
Vela (constellation)
–
List of stars in Vela
98.
Volans
–
Volans is a constellation in the southern sky. It represents a flying fish, its name is a form of its original name. The first depiction of this constellation in an atlas was in Johann Bayers Uranometria of 1603. Volans is one of the 12 constellations that were introduced by the Dutch navigators Pieter Dirkszoon Keyser and it was first depicted on Petrus Plancius’ globe in 1598. In 1603, Johann Bayer included the constellation in his star atlas Uranometria under the name Piscis Volans, john Herschel proposed shrinking the name to one word in 1844, noting that Lacaille himself had abbreviated his constellations thus on occasion. Volans represents a type of fish that can jump out of the water. In early celestial maps, the fish was often depicted as accompanying the ship Argo Navis. The magnitudes of the Gamma Volantis stars are fourth and sixth, HD76700 is a sunlike star some 195 light-years distant that has been found to have a planet. Volans has several deep-sky objects within its borders, the Lindsay-Shapley ring, also categorized as AM0644-741, is a ring galaxy located 300 million light-years from Earth. Named for its discoverers, the Lindsay-Shapley ring was found near the Large Magellanic Cloud in 1960, like the Cartwheel Galaxy in Sculptor, the unusual shape of this galaxy results from a collision many millions of years ago. The blue ring,150,000 light-years in diameter, was formed when a wave from the collision created a ring of hot blue stars. NGC2442, a galaxy, is also located in this constellation. Ridpath, Ian, Tirion, Wil, Stars and Planets Guide, Princeton University Press, ISBN 978-0-691-13556-4 Staal, the New Patterns in the Sky, McDonald and Woodward Publishing Company, ISBN 0-939923-04-1 Wilkins, Jamie, Dunn, Robert. 300 Astronomical Objects, A Visual Reference to the Universe
Volans
–
List of stars in Volans
99.
Argo Navis
–
Argo Navis, or simply Argo, was a large constellation in the Earths southern sky that has since been divided into three constellations. It was identified with the Argo, the used by Jason. The genitive was Argus Navis, abbreviated Arg, flamsteed and other early modern astronomers called the constellation just Navis, genitive Navis, abbreviated Nav. Due to precession, the stars of Argo have been shifted farther south since Classical times, the original constellation was found low near the southern horizon of the Mediterranean sky. The ship became visible in springtime and sailed westward, skimming along the southern horizon, the ancient Greeks identified it with the ship sailed by Jason and the Argonauts to Colchis in search of the Golden Fleece. Argo Navis is the one of the 48 constellations listed by the 2nd century astronomer Ptolemy that is no longer officially recognized as a constellation. It was unwieldy due to its enormous size, similarly, faint non-lettered stars were listed only as in Argûs. The final breakup and abolition of Argo Navis was proposed by Sir John Herschel in 1841 and again in 1844, but it was not formalised until 1930 when the IAU defined the 88 modern constellations. Lacailles designations were kept in the three separate constellations, so Carina has α, β and ε, Vela has γ and δ, Puppis has ζ, the constellation Pyxis occupies an area which in antiquity was considered part of Argos mast. Some authors state that Pyxis was part of the Greek conception of Argo Navis, lacaille considered it a separate constellation, representing one of the modern scientific instruments he placed among the constellations. Pyxis was listed separately, among his 14 new constellations, lacaille assigned Bayer designations to Pyxis separate from those of Argo, and his illustration shows an isolated instrument not related to the figure of the ship. In 1844 John Herschel suggested formalizing the mast as a new constellation, Malus, to replace Lacailles Pyxis, the Māori had several names for what was the constellation Argo, including Te Waka-o-Tamarereti, Te Kohi-a-Autahi, and Te Kohi. Asterism List of stars in Argo Navis Starry Night Photography, Argo Navis Image Star Tales – Argo Navis Warburg Institute Iconographic Database – Argo
Argo Navis
–
The constellation Argo Navis drawn by
Johannes Hevelius
. doi:10.1051/0004-6361:20078357.
