1.
Constellation
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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
2.
Open cluster
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An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way Galaxy and they are loosely bound by mutual gravitational attraction and become disrupted by close encounters with other clusters and clouds of gas as they orbit the galactic center. This can result in a migration to the body of the galaxy. Open clusters generally survive for a few hundred years, with the most massive ones surviving for a few billion years. In contrast, the more massive clusters of stars exert a stronger gravitational attraction on their members. Open clusters have been only in spiral and irregular galaxies. Young open clusters may not be contained within the cloud from which they formed. Over time, radiation pressure from the cluster will disperse the molecular cloud, typically, about 10% of the mass of a gas cloud will coalesce into stars before radiation pressure drives the rest of the gas away. Open clusters are key objects in the study of stellar evolution, because the cluster members are of similar age and chemical composition, their properties are more easily determined than they are for isolated stars. A number of clusters, such as the Pleiades, Hyades or the Alpha Persei Cluster are visible with the naked eye. Some others, such as the Double Cluster, are barely perceptible without instruments, the Wild Duck Cluster, M11, is an example. The prominent open cluster the Pleiades has been recognized as a group of stars since antiquity, while the Hyades forms part of Taurus, other open clusters were noted by early astronomers as unresolved fuzzy patches of light. The Roman astronomer Ptolemy mentions the Praesepe, the Double Cluster in Perseus, however, it would require the invention of the telescope to resolve these nebulae into their constituent stars. Indeed, in 1603 Johann Bayer gave three of these clusters designations as if they were single stars, the first person to use a telescope to observe the night sky and record his observations was the Italian scientist Galileo Galilei in 1609. When he turned the telescope toward some of the nebulous patches recorded by Ptolemy, he found they were not a single star, for Praesepe, he found more than 40 stars. Where previously observers had noted only 6-7 stars in the Pleiades, in his 1610 treatise Sidereus Nuncius, Galileo Galilei wrote, the galaxy is nothing else but a mass of innumerable stars planted together in clusters. Influenced by Galileos work, the Sicilian astronomer Giovanni Hodierna became possibly the first astronomer to use a telescope to find previously undiscovered open clusters, in 1654, he identified the objects now designated Messier 41, Messier 47, NGC2362 and NGC2451. Between 1774–1781, French astronomer Charles Messier published a catalogue of objects that had a nebulous appearance similar to comets
3.
Charles Messier
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Charles Messier was a French astronomer most notable for publishing an astronomical catalogue consisting of nebulae and star clusters that came to be known as the 110 Messier objects. The purpose of the catalogue was to help astronomical observers, in particular comet hunters such as himself, Messier was born in Badonviller in the Lorraine region of France, being the tenth of twelve children of Françoise B. Grandblaise and Nicolas Messier, a Court usher, six of his brothers and sisters died while young and in 1741, his father died. Charles interest in astronomy was stimulated by the appearance of the spectacular, great six-tailed comet in 1744, in 1751 he entered the employ of Joseph Nicolas Delisle, the astronomer of the French Navy, who instructed him to keep careful records of his observations. Messiers first documented observation was that of the Mercury transit of 6 May 1753, according to Meyer, Messier is buried in Père Lachaise Cemetery, Paris, in Section 11. Messiers occupation as a comet hunter led him to come across fixed diffuse objects in the night sky which could be mistaken for comets. He compiled a list of them, in collaboration with his friend and assistant Pierre Méchain, the entries are now known to be galaxies, planetary nebulae, other types of nebulae, and star clusters. Messier did his observing with a 100 mm refracting telescope from Hôtel de Cluny, in downtown Paris, the list he compiled contains only objects found in the area of the sky he could observe, from the north celestial pole to a declination of about −35. 7°. They are not organized scientifically by object type, or even by location, the first version of Messiers catalogue contained 45 objects and was published in 1774 in the journal of the French Academy of Sciences in Paris. In addition to his own discoveries, this version included objects previously observed by other astronomers, by 1780 the catalog had increased to 80 objects. The final version of the catalogue was published in 1781, in the 1784 issue of Connaissance des Temps, the final list of Messier objects had grown to 103. These seven objects, M104 through M110, are accepted by astronomers as official Messier objects, the crater Messier on the Moon and the asteroid 7359 Messier were named in his honor. Deep sky object List of Messier objects Messier object Messier marathon Caldwell catalogue OMeara, deep Sky Companions, The Messier Objects. Charles Messier Biography at Students for the Exploration and Development of Space, retrieved July 2007 Short biography of Charles Messier and history of the Messier Object Catalog by Jon Zander at OurDarkSkies. com. Retrieved July 2007 Life of a Comet Hunter, Messier and Astrobiology Professor Mark Brake and Martin Griffiths, Astrobiology Magazine European Edition, retrieved July 2007 Interactive Messier Catalog Greenhawk Observatory Amateur Photos of Charles Messier Objects Biography - Messier website. Messier Marathon Attempts to find as many Messier objects as possible in one night, retrieved July 2007 Clickable table of Messier objects Charles Messier explains his catalog on YouTube
4.
Star
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A star is a luminous sphere of plasma held together by its own gravity. The nearest star to Earth is the Sun, many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. However, most of the stars in the Universe, including all stars outside our galaxy, indeed, most are invisible from Earth even through the most powerful telescopes. Almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the stars lifetime, near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity, and many properties of a star by observing its motion through space, its luminosity. The total mass of a star is the factor that determines its evolution. Other characteristics of a star, including diameter and temperature, change over its life, while the environment affects its rotation. A plot of the temperature of stars against their luminosities produces a plot known as a Hertzsprung–Russell diagram. Plotting a particular star on that allows the age and evolutionary state of that star to be determined. A stars life begins with the collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium. When the stellar core is sufficiently dense, hydrogen becomes steadily converted into helium through nuclear fusion, the remainder of the stars interior carries energy away from the core through a combination of radiative and convective heat transfer processes. The stars internal pressure prevents it from collapsing further under its own gravity, a star with mass greater than 0.4 times the Suns will expand to become a red giant when the hydrogen fuel in its core is exhausted. In some cases, it will fuse heavier elements at the core or in shells around the core, as the star expands it throws a part of its mass, enriched with those heavier elements, into the interstellar environment, to be recycled later as new stars. Meanwhile, the core becomes a remnant, a white dwarf. Binary and multi-star systems consist of two or more stars that are bound and generally move around each other in stable orbits. When two such stars have a close orbit, their gravitational interaction can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, historically, stars have been important to civilizations throughout the world
5.
Duck
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Duck is the common name for a large number of species in the waterfowl family Anatidae, which also includes swans and geese. The ducks are divided among several subfamilies in the family Anatidae, they do not represent a group but a form taxon, since swans. Ducks are mostly birds, mostly smaller than the swans and geese. Ducks are sometimes confused with several types of unrelated water birds with similar forms, such as loons or divers, grebes, gallinules and this word replaced Old English ened/ænid duck, possibly to avoid confusion with other Old English words, like ende end with similar forms. Other Germanic languages still have similar words for duck, for example, Dutch eend duck, the word ened/ænid was inherited from Proto-Indo-European, compare, Latin anas duck, Lithuanian ántis duck, Ancient Greek nēssa/nētta duck, and Sanskrit ātí water bird, among others. A duckling is a duck in downy plumage or baby duck. A male duck is called a drake and the female is called a duck, the overall body plan of ducks is elongated and broad, and the ducks are also relatively long-necked, albeit not as long-necked as the geese and swans. The body shape of diving ducks varies somewhat from this in being more rounded, the bill is usually broad and contains serrated lamellae, which are particularly well defined in the filter-feeding species. In the case of some fishing species the bill is long, the scaled legs are strong and well developed, and generally set far back on the body, more so in the highly aquatic species. The wings are strong and are generally short and pointed. Three species of duck are almost flightless, however. Many species of duck are temporarily flightless while moulting, they seek out protected habitat with good food supplies during this period, the drakes of northern species often have extravagant plumage, but that is moulted in summer to give a more female-like appearance, the eclipse plumage. The plumage of birds generally resembles that of the female. Over the course of evolution, female ducks have evolved to have a corkscrew shaped vagina to prevent rape, Ducks exploit a variety of food sources such as grasses, aquatic plants, fish, insects, small amphibians, worms, and small molluscs. Dabbling ducks feed on the surface of water or on land, along the edge of the beak there is a comb-like structure called a pecten. This strains the water squirting from the side of the beak, the pecten is also used to preen feathers and to hold slippery food items. Diving ducks and sea ducks forage deep underwater, to be able to submerge more easily, the diving ducks are heavier than dabbling ducks, and therefore have more difficulty taking off to fly. A few specialized species such as the mergansers are adapted to catch, to avoid injury when digging into sediment it has no cere, but the nostrils come out through hard horn
6.
Crab Nebula
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The Crab Nebula is a supernova remnant in the constellation of Taurus. The now-current name is due to William Parsons, 3rd Earl of Rosse, corresponding to a bright supernova recorded by Chinese astronomers in 1054, the nebula was observed later by English astronomer John Bevis in 1731. The nebula was the first astronomical object identified with a supernova explosion. At an apparent magnitude of 8.4, comparable to that of Saturns moon Titan, it is not visible to the naked eye, the nebula lies in the Perseus Arm of the Milky Way galaxy, at a distance of about 2.0 kiloparsecs from Earth. It has a diameter of 3.4 parsecs, corresponding to an apparent diameter of some 7 arcminutes, and is expanding at a rate of about 1,500 kilometres per second, or 0. 5% of the speed of light. At the center of the lies the Crab Pulsar, a neutron star 28–30 kilometres across with a spin rate of 30.2 times per second. At X-ray and gamma ray energies above 30 keV, the Crab Nebula is generally the strongest persistent source in the sky, the nebulas radiation allows for the detailed studying of celestial bodies that occult it. The inner part of the nebula is a much smaller pulsar wind nebula that appears as a shell surrounding the pulsar, for the Crab Nebula, the divisions are superficial but remain meaningful to researchers and their lines of study. Modern understanding that the Crab Nebula was created by a supernova dates to 1921 and this eventually led to the conclusion that the creation of the Crab Nebula corresponds to the bright SN1054 supernova recorded by Chinese astronomers in AD1054. There is also a 13th-century Japanese reference to this guest star in Meigetsuki, the Crab Nebula was first identified in 1731 by John Bevis. The nebula was independently rediscovered in 1758 by Charles Messier as he was observing a bright comet and it is in searching in vain for the comet that Charles Messier found the Crab nebula, which he at first thought to be Halleys comet. After some observation, noticing that the object that he was observing was not moving across the sky, Messier then realised the usefulness of compiling a catalogue of celestial objects of a cloudy nature, but fixed in the sky, to avoid incorrectly cataloguing them as comets. After several observations, he concluded that it was composed of a group of stars. The 3rd Earl of Rosse observed the nebula at Birr Castle in 1844 using a 36-inch telescope and he observed it again later, in 1848, using a 72-inch telescope and could not confirm the supposed resemblance, but the name stuck nevertheless. In 1913, when Vesto Slipher registered his spectroscopy study of the sky, in the early twentieth century, the analysis of early photographs of the nebula taken several years apart revealed that it was expanding. Tracing the expansion back revealed that the nebula must have become visible on Earth about 900 years ago, historical records revealed that a new star bright enough to be seen in the daytime had been recorded in the same part of the sky by Chinese astronomers in 1054. Changes in the cloud, suggesting its small extent, were discovered by Carl Lampland in 1921 and that same year, John Charles Duncan demonstrated that the remnant is expanding, while Knut Lundmark noted its proximity to the guest star of 1054.5 by July. The supernova was visible to the eye for about two years after its first observation
7.
Messier 4
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Messier 4 or M4 is a globular cluster in the constellation of Scorpius. It was discovered by Philippe Loys de Chéseaux in 1745 and catalogued by Charles Messier in 1764 and it was the first globular cluster in which individual stars were resolved. M4 is conspicuous in even the smallest of telescopes as a ball of light. It appears about the size as the Moon in the sky. It is one of the easiest globular clusters to find, being located only 1.3 degrees west of the bright star Antares, modestly sized telescopes will begin to resolve individual stars, of which the brightest in M4 are of apparent magnitude 10.8. M4 is a rather loosely concentrated cluster of class IX and measures 75 light years across and it features a characteristic bar structure across its core, visible to moderate sized telescopes. The structure consists of 11th magnitude stars and is approximately 2.5 long and was first noted by William Herschel in 1783, at least 43 variable stars have been observed within M4. M4 is approximately 7,200 light years away, the distance as NGC6397. It has an age of 12.2 billion years. In astronomy, the abundance of other than hydrogen and helium is called the metallicity. For this cluster, the abundance of iron is equal to. Thus the cluster has an abundance of iron equal to 8. 5% of the abundance in the Sun. Based upon the measurements, there is evidence that this cluster hosts two distinct stellar populations. Each of the populations is a group of stars that all formed at about the same time, thus the cluster may have undergone at least two separate cycles of star formation. The space velocity components of this cluster are = km/s and it is following an orbit through the Milky Way that has a period of million years and an eccentricity of 0.80 ±0.03. During periapsis it comes within kpc from the core, while at apoapsis it travels out to a distance of kpc. The orbital inclination is at an angle of 23° ± 6° from the galactic plane, when passing through the disk, this cluster does so at distances of less than 5 kpc from the galactic nucleus. The cluster undergoes tidal shock during each passage, which can cause the repeated shedding of stars, thus the cluster may have been much more massive in the past
8.
Lagoon Nebula
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The Lagoon Nebula is a giant interstellar cloud in the constellation Sagittarius. It is classified as an emission nebula and as an H II region, the Lagoon Nebula was discovered by Giovanni Hodierna before 1654 and is one of only two star-forming nebulae faintly visible to the eye from mid-northern latitudes. Seen with binoculars, it appears as a distinct oval cloudlike patch with a definite core, in the foreground is the open cluster NGC6530. The Lagoon Nebula is estimated to be between 4, 000-6,000 light-years from the Earth, in the sky of Earth, it spans 90 by 40, which translates to an actual dimension of 110 by 50 light years. Like many nebulas, it appears pink in time-exposure color photos but is gray to the eye peering through binoculars or a telescope, human vision having poor color sensitivity at low light levels. The nebula contains a number of Bok globules, the most prominent of which have been catalogued by E. E. Barnard as B88, B89 and B296. It also includes a funnel-like or tornado-like structure caused by a hot O-type star that emanates ultraviolet light, the Lagoon Nebula also contains at its centre a structure known as the Hourglass Nebula, which should not be confused with the better known Hourglass Nebula in the constellation of Musca. In 2006 the first four Herbig–Haro objects were detected within the Hourglass and this provides the first direct evidence of active star formation by accretion within it. List of Messier objects Lists of nebulae Breaking Waves in the Stellar Lagoon — ESA/Hubble Photo Release Messier 8, SEDS Messier pages NightSkyInfo
9.
Messier 12
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Messier 12 or M12 is a globular cluster in the constellation of Ophiuchus. It was discovered by the French astronomer Charles Messier on May 30,1764, in dark conditions this cluster can be faintly seen with a pair of binoculars. Resolving the stellar components requires a telescope with an aperture of 8 in or greater, in a 10 in scope, the granular core shows a diameter of 3′ surrounded by a 10′ halo of stars. Located roughly 3° in the sky from the cluster M10 and 5. 6° from the star Lambda Ophiuchi, the brightest stars of M12 are of 12th magnitude. With a Shapley-Sawyer rating of IX, it is loosely packed for a globular and was once thought to be a tightly concentrated open cluster. Thirteen variable stars have been recorded in this cluster, M12 is approaching us at a velocity of 16 km/s. A study published in 2006 concluded that this cluster has a low number of low mass stars. The authors surmise that they were stripped from the cluster by the influence of the Milky Way
10.
Eagle Nebula
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The Eagle Nebula is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Chéseaux in 1745–46. The nebula contains several active star-forming gas and dust regions, including the Pillars of Creation, the Eagle Nebula is part of a diffuse emission nebula, or H II region, which is catalogued as IC4703. This region of current star formation is about 7000 light-years distant. A spire of gas that can be seen coming off the nebula in the part is approximately 9.5 light-years or about 90 trillion kilometers long. The cluster associated with the nebula has approximately 8100 stars, which are concentrated in a gap in the molecular cloud to the north-west of the Pillars. The brightest star has an apparent magnitude of +8.24 and it is actually a binary star formed of an O3. 5V star plus an O7. 5V companion. This star has a mass of roughly 80 solar masses, the clusters age has been estimated to be 1–2 million years. The descriptive names reflect impressions of the shape of the central pillar rising from the southeast into the central luminous area, the name Star Queen Nebula was introduced by Robert Burnham, Jr. reflecting his characterization of the central pillar as the Star Queen shown in silhouette. Images taken by Jeff Hester and Paul Scowen using the Hubble Space Telescope in 1995 greatly improved understanding of processes inside the nebula. One of these photographs became famous as the Pillars of Creation, the small dark areas in the photograph are believed to be protostars. These columns – which resemble stalagmites protruding from the floor of a cavern – are composed of hydrogen gas and dust. Inside the columns and on their surface astronomers have found knots or globules of denser gas, stars are being formed inside some of these EGGs. X-ray images from the Chandra observatory compared with Hubbles Pillars image have shown that X-ray sources do not coincide with the pillars, any protostars in the pillars EGGs are not yet hot enough to emit X-rays. Evidence from the Spitzer Telescope suggests that the pillars in M16 may already have been destroyed by a supernova explosion, hot gas observed by Spitzer in 2007 suggests that the area was disturbed by a supernova that exploded some 8000 to 9000 years ago
11.
Omega Nebula
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The Omega Nebula, also known as the Swan Nebula, Checkmark Nebula, and the Horseshoe Nebula is an H II region in the constellation Sagittarius. It was discovered by Philippe Loys de Chéseaux in 1745, charles Messier catalogued it in 1764. It is located in the rich starfields of the Sagittarius area of the Milky Way, the Omega Nebula is between 5,000 and 6,000 light-years from Earth and it spans some 15 light-years in diameter. The cloud of matter of which this nebula is a part is roughly 40 light-years in diameter and has a mass of 30,000 solar masses. The total mass of the Omega Nebula is an estimated 800 solar masses and it is considered one of the brightest and most massive star-forming regions of our galaxy. Its local geometry is similar to the Orion Nebula except that it is viewed edge-on rather than face-on and it is also one of the youngest clusters known, with an age of just 1 million years. The luminous blue variable HD168607, located in the south-east part of the Omega nebula, is assumed to be associated with it, its close neighbor. The Swan portion of M17, the Omega Nebula in the Sagittarius nebulosity is said to resemble a barber’s pole, the first attempt to accurately draw the nebula was made by John Herschel in 1833, and published in 1836. He described the nebula as such, A second, more detailed sketch was made during his visit to South Africa in 1837, the nebula was also studied by Johann von Lamont and separately by an undergraduate at Yale College, Mr Mason, starting from around 1836
12.
Trifid Nebula
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The Trifid Nebula is an H II region located in Sagittarius. It was discovered by Charles Messier on June 5,1764 and its name means divided into three lobes. The object is a combination of an open cluster of stars, an emission nebula, a reflection nebula. Viewed through a telescope, the Trifid Nebula is a bright and peculiar object. The Trifid Nebula is a region in the Scutum spiral arm of the Milky Way. The most massive star that has formed in this region is HD 164492A and this star is surrounded by a cluster of approximately 3100 young stars. The images were combined into a composite picture to suggest how the nebula might look to the eye. The close-up images show a cloud of dust and gas. This cloud is about 8 ly away from the central star. A stellar jet protrudes from the head of the cloud and is about 0.75 ly long, the jets source is a young stellar object deep within the cloud. Jets are the exhaust gasses of star formation and radiation from the central star makes the jet glow. The images also showed a finger-like stalk to the right of the jet and it points from the head of the dense cloud directly toward the star that powers the Trifid nebula. This stalk is a prominent example of evaporating gaseous globules, or EGGs, the stalk has survived because its tip is a knot of gas that is dense enough to resist being eaten away by the powerful radiation from the star. In January 2005, NASAs Spitzer Space Telescope discovered 30 embryonic stars and 120 newborn stars not seen in visible light images and it is approximately 5000 ly away from Earth. The Trifid Nebula on WikiSky, DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images Trifid Nebula at Constellation Guide
18h 51.1m 00s, −06° 16′ 00″
