1.
Naked eye
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Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying or light-collecting optical device, such as a telescope or microscope. Vision corrected to normal acuity using corrective lenses is considered naked, in astronomy, the naked eye may be used to observe events that can be viewed without equipment, such as an astronomical conjunction, the passage of a comet, or a meteor shower. Sky lore and various tests demonstrate a wealth of phenomena that can be seen with the unaided eye. The basic accuracies of the eye are, Quick autofocus from distances of 25 cm to 50 cm to infinity. Angular resolution, about 1 arcminute, approximately 0. 02° or 0.0003 radians, field of view, simultaneous visual perception in an area of about 160° × 175°. Faint stars up to +8 magnitude under a dark sky. Photometry to ±10% or 1% of intensity – in a range between night and day of 1,10,000,000,000, symmetries of 10–20, see the measurements of Tycho Brahe and the Egyptians. Even a few hundred kilometers away from an area where the sky can appear to be very dark. For most people, these are likely to be the best observing conditions within their reach, under such typical dark sky conditions, the naked eye can see stars with an apparent magnitude up to +6m. Under perfect dark sky conditions where all light pollution is absent, the angular resolution of the naked eye is about 1′, however, some people have sharper vision than that. There is anecdotal evidence that people had seen the Galilean moons of Jupiter before telescopes were invented, Uranus, when discovered in 1781, was the first planet discovered using technology rather than being spotted by the naked eye. In practice, the extinction and dust reduces this number somewhat. In the center of a city, where the limiting magnitude due to extreme amounts of light pollution can be +4m or less. Colors can be seen but this is limited by the fact that the eye uses rods instead of cones to view fainter stars, the visibility of diffuse objects such as star clusters and galaxies is much more strongly affected by light pollution than is that of planets and stars. Under typical dark conditions only a few objects are visible. The Triangulum Galaxy is a difficult averted vision object and only visible at all if it is higher than 50° in the sky, the globular clusters M3 in Canes Venatici and M92 in Hercules are also visible with the naked eye under such conditions. Under really dark sky conditions, however, M33 is easy to see, many other Messier objects are also visible under such conditions. The most distant objects that have seen by the naked eye are nearby bright galaxies such as Centaurus A, Bodes Galaxy, Sculptor Galaxy
2.
88 modern constellations
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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
3.
England
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England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west, the Irish Sea lies northwest of England and the Celtic Sea lies to the southwest. England is separated from continental Europe by the North Sea to the east, the country covers five-eighths of the island of Great Britain in its centre and south, and includes over 100 smaller islands such as the Isles of Scilly, and the Isle of Wight. England became a state in the 10th century, and since the Age of Discovery. The Industrial Revolution began in 18th-century England, transforming its society into the worlds first industrialised nation, Englands terrain mostly comprises low hills and plains, especially in central and southern England. However, there are uplands in the north and in the southwest, the capital is London, which is the largest metropolitan area in both the United Kingdom and the European Union. In 1801, Great Britain was united with the Kingdom of Ireland through another Act of Union to become the United Kingdom of Great Britain and Ireland. In 1922 the Irish Free State seceded from the United Kingdom, leading to the latter being renamed the United Kingdom of Great Britain, the name England is derived from the Old English name Englaland, which means land of the Angles. The Angles were one of the Germanic tribes that settled in Great Britain during the Early Middle Ages, the Angles came from the Angeln peninsula in the Bay of Kiel area of the Baltic Sea. The earliest recorded use of the term, as Engla londe, is in the ninth century translation into Old English of Bedes Ecclesiastical History of the English People. According to the Oxford English Dictionary, its spelling was first used in 1538. The earliest attested reference to the Angles occurs in the 1st-century work by Tacitus, Germania, the etymology of the tribal name itself is disputed by scholars, it has been suggested that it derives from the shape of the Angeln peninsula, an angular shape. An alternative name for England is Albion, the name Albion originally referred to the entire island of Great Britain. The nominally earliest record of the name appears in the Aristotelian Corpus, specifically the 4th century BC De Mundo, in it are two very large islands called Britannia, these are Albion and Ierne. But modern scholarly consensus ascribes De Mundo not to Aristotle but to Pseudo-Aristotle, the word Albion or insula Albionum has two possible origins. Albion is now applied to England in a poetic capacity. Another romantic name for England is Loegria, related to the Welsh word for England, Lloegr, the earliest known evidence of human presence in the area now known as England was that of Homo antecessor, dating to approximately 780,000 years ago. The oldest proto-human bones discovered in England date from 500,000 years ago, Modern humans are known to have inhabited the area during the Upper Paleolithic period, though permanent settlements were only established within the last 6,000 years
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.
Bayer designation
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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
6.
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
7.
Right ascension
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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
8.
Precession
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Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, in other words, if the axis of rotation of a body is itself rotating about a second axis, that body is said to be precessing about the second axis. A motion in which the second Euler angle changes is called nutation, in physics, there are two types of precession, torque-free and torque-induced. In astronomy, precession refers to any of several changes in an astronomical bodys rotational or orbital parameters. An important example is the change in the orientation of the axis of rotation of the Earth. Torque-free precession implies that no moment is applied to the body. In torque-free precession, the momentum is a constant. What makes this possible is a moment of inertia, or more precisely. The inertia matrix is composed of the moments of inertia of a body calculated with respect to coordinate axes. If an object is asymmetric about its axis of rotation. The result is that the component of the velocities of the body about each axis will vary inversely with each axis moment of inertia. When an object is not perfectly solid, internal vortices will tend to damp torque-free precession, R new = exp R old for the skew-symmetric matrix ×. Torque-induced precession is the phenomenon in which the axis of a spinning object describes a cone in space when a torque is applied to it. The phenomenon is seen in a spinning toy top. If the speed of the rotation and the magnitude of the external torque are constant, the spin axis will move at right angles to the direction that would intuitively result from the external torque. In the case of a toy top, its weight is acting downwards from its center of mass and these two opposite forces produce a torque which causes the top to precess. The device depicted on the right is gimbal mounted, from inside to outside there are three axes of rotation, the hub of the wheel, the gimbal axis, and the vertical pivot. To distinguish between the two axes, rotation around the wheel hub will be called spinning, and rotation around the gimbal axis will be called pitching
9.
John Flamsteed
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John Flamsteed FRS was an English astronomer and the first Astronomer Royal. Flamsteed was born in Denby, Derbyshire, England, the son of Stephen Flamsteed and his first wife. He was educated at the school of Derby, and was educated at Derby School, in St Peters Churchyard, Derby. At that time, most masters of the school were Puritans, Flamsteed had a solid knowledge of Latin, essential for reading the scientific literature of the day, and a love of history, leaving the school in May,1662. His progress to Jesus College, Cambridge, recommended by the Master of Derby School, was delayed by years of chronic ill health. During those years, Flamsteed gave his father some help in his business, and from his father learnt arithmetic and the use of fractions, developing a keen interest in mathematics and astronomy. In July 1662, he was fascinated by the work of Johannes de Sacrobosco, De sphaera mundi. Early in 1663, he read Thomas Fales The Art of Dialling, in the summer of 1663, he read Wingates Canon, William Oughtreds Canon, and Thomas Stirrups Art of Dialling. At about the time, he acquired Thomas Streets Astronomia Carolina. Flamsteed was greatly impressed by the work of Horrocks, in September 1670, Flamsteed visited Cambridge and entered his name as an undergraduate at Jesus College. While it seems he never took up residence, he was there for two months in 1674, and had the opportunity to hear Isaac Newtons Lucasian Lectures. Ordained a deacon, he was preparing to take up a living in Derbyshire when he was invited to London by his patron Jonas Moore, Moore had recently made an offer to the Royal Society to pay for the establishment of an observatory. Charles appointed a Royal Commission to examine the proposal in December 1674, consisting of Lord Brouncker, Seth Ward, Samuel Moreland, Christopher Wren, Silius Titus, John Pell and Robert Hooke. Having arrived in London on 2 February 1675, and staying with Jonas Moore at the Tower of London and he was subsequently admitted as an official Assistant to the Royal Commission and supplied observations in order to test St Pierres proposal and to offer his own comments. On 4 March 1675 Flamsteed was appointed by royal warrant The Kings Astronomical Observator — the first English Astronomer Royal, in June 1675, another royal warrant provided for the founding of the Royal Greenwich Observatory, and Flamsteed laid the foundation stone on 10 August. He held that office, as well as that of Astronomer Royal and he is buried at Burstow, and the east window in the church was dedicated to him as a memorial. The will of Flamsteed’s widow, Margaret, left instructions for her own remains to be deposited “in the same Grave in which Mr John Flamsteed is buryed in the Chancell of Burstow Church. It seems no such monument was created, and almost 200 years later, after his death, his papers and scientific instruments were taken by his widow
10.
Edmond Halley
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Edmond Halley, FRS was an English astronomer, geophysicist, mathematician, meteorologist, and physicist who is best known for computing the orbit of Halleys Comet. He was the second Astronomer Royal in Britain, succeeding John Flamsteed, Halley was born in Haggerston, in east London. His father, Edmond Halley Sr. came from a Derbyshire family and was a wealthy soap-maker in London, as a child, Halley was very interested in mathematics. He studied at St Pauls School, and from 1673 at The Queens College, while still an undergraduate, Halley published papers on the Solar System and sunspots. While at Oxford University, Halley was introduced to John Flamsteed, influenced by Flamsteeds project to compile a catalog of northern stars, Halley proposed to do the same for the Southern Hemisphere. In 1676, Halley visited the south Atlantic island of Saint Helena, while there he observed a transit of Mercury, and realised that a similar transit of Venus could be used to determine the absolute size of the Solar System. He returned to England in May 1678, in the following year he went to Danzig on behalf of the Royal Society to help resolve a dispute. Because astronomer Johannes Hevelius did not use a telescope, his observations had been questioned by Robert Hooke, Halley stayed with Hevelius and he observed and verified the quality of Hevelius observations. In 1679, Halley published the results from his observations on St. Helena as Catalogus Stellarum Australium which included details of 341 southern stars and these additions to contemporary star maps earned him comparison with Tycho Brahe, e. g. the southern Tycho as described by Flamsteed. Halley was awarded his M. A. degree at Oxford, in 1686, Halley published the second part of the results from his Helenian expedition, being a paper and chart on trade winds and monsoons. The symbols he used to represent trailing winds still exist in most modern day weather chart representations, in this article he identified solar heating as the cause of atmospheric motions. He also established the relationship between pressure and height above sea level. His charts were an important contribution to the field of information visualisation. Halley spent most of his time on lunar observations, but was interested in the problems of gravity. One problem that attracted his attention was the proof of Keplers laws of planetary motion, Halleys first calculations with comets were thereby for the orbit of comet Kirch, based on Flamsteeds observations in 1680-1. Although he was to calculate the orbit of the comet of 1682. They indicated a periodicity of 575 years, thus appearing in the years 531 and 1106 and it is now known to have an orbital period of circa 10,000 years. In 1691, Halley built a bell, a device in which the atmosphere was replenished by way of weighted barrels of air sent down from the surface
11.
Isaac Newton
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His book Philosophiæ Naturalis Principia Mathematica, first published in 1687, laid the foundations of classical mechanics. Newton also made contributions to optics, and he shares credit with Gottfried Wilhelm Leibniz for developing the infinitesimal calculus. Newtons Principia formulated the laws of motion and universal gravitation that dominated scientists view of the universe for the next three centuries. Newtons work on light was collected in his influential book Opticks. He also formulated a law of cooling, made the first theoretical calculation of the speed of sound. Newton was a fellow of Trinity College and the second Lucasian Professor of Mathematics at the University of Cambridge, politically and personally tied to the Whig party, Newton served two brief terms as Member of Parliament for the University of Cambridge, in 1689–90 and 1701–02. He was knighted by Queen Anne in 1705 and he spent the last three decades of his life in London, serving as Warden and Master of the Royal Mint and his father, also named Isaac Newton, had died three months before. Born prematurely, he was a child, his mother Hannah Ayscough reportedly said that he could have fit inside a quart mug. When Newton was three, his mother remarried and went to live with her new husband, the Reverend Barnabas Smith, leaving her son in the care of his maternal grandmother, Newtons mother had three children from her second marriage. From the age of twelve until he was seventeen, Newton was educated at The Kings School, Grantham which taught Latin and Greek. He was removed from school, and by October 1659, he was to be found at Woolsthorpe-by-Colsterworth, Henry Stokes, master at the Kings School, persuaded his mother to send him back to school so that he might complete his education. Motivated partly by a desire for revenge against a bully, he became the top-ranked student. In June 1661, he was admitted to Trinity College, Cambridge and he started as a subsizar—paying his way by performing valets duties—until he was awarded a scholarship in 1664, which guaranteed him four more years until he would get his M. A. He set down in his notebook a series of Quaestiones about mechanical philosophy as he found it, in 1665, he discovered the generalised binomial theorem and began to develop a mathematical theory that later became calculus. Soon after Newton had obtained his B. A. degree in August 1665, in April 1667, he returned to Cambridge and in October was elected as a fellow of Trinity. Fellows were required to become ordained priests, although this was not enforced in the restoration years, however, by 1675 the issue could not be avoided and by then his unconventional views stood in the way. Nevertheless, Newton managed to avoid it by means of a special permission from Charles II. A and he was elected a Fellow of the Royal Society in 1672. Newtons work has been said to distinctly advance every branch of mathematics then studied and his work on the subject usually referred to as fluxions or calculus, seen in a manuscript of October 1666, is now published among Newtons mathematical papers
12.
51 Pegasi
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51 Pegasi, also named Helvetios, is a Sun-like star located 50.9 light-years from Earth in the constellation of Pegasus. It was the first main-sequence star found to have an exoplanet orbiting it, the star is of apparent magnitude 5.49, and so is visible with the naked eye under suitable viewing conditions. 51 Pegasi has a classification of G5V, indicating that it is a main-sequence star that is generating energy through the thermonuclear fusion of hydrogen at its core. The effective temperature of the chromosphere is about 5571 K, giving 51 Pegasi the characteristic yellow hue of a G-type star. It is estimated to be 6. 1–8.1 billion years old, somewhat older than the Sun, with a radius 24% larger, the star has a higher proportion of elements other than hydrogen/helium compared to the Sun, a quantity astronomers term a stars metallicity. Stars with higher metallicity such as this are likely to host planets. In 1996 astronomers Baliunas, Sokoloff, and Soon measured a rotational period of 37 days for 51 Pegasi, although the star was suspected of being variable during a 1981 study, subsequent observation showed there was almost no chromospheric activity between 1977 and 1989. Further examination between 1994 and 2007 showed a low or flat level of activity. This, along with its relatively low X-ray emission, suggests that the star may be in a Maunder minimum period during which a star produces a number of star spots. The star rotates at an inclination of 79+11 −30 degrees relative to Earth,51 Pegasi is the Flamsteed designation. In July 2014 the International Astronomical Union launched a process for giving proper names to certain exoplanets, the process involved public nomination and voting for the new names. In December 2015, the IAU announced the names were Helvetios for this star. The winning names were submitted by the Astronomische Gesellschaft Luzern. In 2016, the IAU organized a Working Group on Star Names to catalog and this star is now so entered in the IAU Catalog of Star Names. On October 6,1995, Swiss astronomers Michel Mayor and Didier Queloz announced the discovery of an exoplanet orbiting 51 Pegasi, the discovery was made with the radial velocity method on a telescope at Observatoire de Haute-Provence in France and using the ELODIE spectrograph. 51 Pegasi b is the first discovered planetary-mass companion of its parent star, at the time, this close distance was not compatible with theories of planet formation and resulted in discussions of planetary migration. It has been assumed that the shares the stars inclination of 79 degrees. However, several hot Jupiters are now known to be relative to the stellar axis
13.
61 Cygni
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61 Cygni /ˈsɪɡnɪ/ is a binary star system in the constellation Cygnus, consisting of a pair of K-type dwarf stars that orbit each other in a period of about 659 years. Of apparent magnitude 5.20 and 6.05, respectively,61 Cygni first attracted the attention of astronomers when its large proper motion was first demonstrated by Giuseppe Piazzi in 1804. Among all stars or stellar systems listed in the modern Hipparcos Catalogue,61 Cygni currently has the seventh-highest proper motion, no habitable planets have been confirmed in this stellar system to date. 61 Cygni is relatively dim, so it not appear on ancient star maps. The name 61 Cygni is part of the Flamsteed designation assigned to stars and it has also been called Bessels Star or Piazzis Flying Star. The first well recorded observation of the system using optical instruments was made by James Bradley on 25 September 1753. William Herschel began systematic observations of 61 Cygni as part of a study of binary stars. In 1792, Giuseppe Piazzi noticed the high proper motion when he compared his own observations of 61 Cygni with those of Bradley and this led to considerable interest in 61 Cygni by contemporary astronomers, and its continual observation since that date. Piazzis repeated measurements led to a value of its motion. It was in this record he christened the system as the Flying Star, peters calculated a better value based on observations made by Bernhard von Lindenau at Seeburg between 1812 and 1814, he calculated it to be 470 ±510 mas. Friedrich Wilhelm Bessel made a contribution in 1812 when he used a different method to measure distance. Assuming the orbital period of the two stars in the binary to be 400 years, he estimated the distance between the two this would require, and then measured the distance between the stars. This led to a value of 460 mas and he then followed this up with direct parallax measurements in a series of observations between 1815 and 1816, comparing it with six other stars. The two sets of measurements produced values of 760 and 1320 mas, all of these estimates, like earlier attempts by others, retained inaccuracies greater than the measurements. When Joseph von Fraunhofer invented a new type of heliometer, Bessel carried out another set of measurements using this device in 1837 and 1838 at Königsberg. He published his findings in 1838 with a value of 369. 0±19.1 mas to A and 260. 5±18.8 to B and this corresponds to a distance of about 600,000 astronomical units, or about 10.4 light-years. This was the first direct and reliable measurement of the distance to an other than the Sun. His measurement was published shortly before similar parallax measurements of Vega by Friedrich Georg Wilhelm von Struve
14.
55 Cancri
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55 Cancri is a binary star approximately 41 light-years away from the Sun in the constellation of Cancer. The system consists of a G-type star and a red dwarf. As of 2015, five planets are believed to orbit 55 Cancri A.55 Cancri is the systems Flamsteed designation. It also bears the Bayer designation ρ¹ Cancri and the Bright Star Catalogue designation HR3522, the two components are designated A and B, though A is itself sometimes referred to as 55 Cancri. The first planet discovered orbiting 55 Cancri A was designated HR 3522b by its discoverers, under the rules for naming objects in binary star systems it should be named 55 Cancri Ab and this more formal form is occasionally used to avoid confusion with the secondary star 55 Cancri B. The other planets discovered were designated 55 Cancri c, d, e and f, in July 2014 the International Astronomical Union launched a process for giving proper names to certain exoplanets and their host stars. The process involved public nomination and voting for the new names, in December 2015, the IAU announced the winning names were Copernicus for 55 Cancri A and Galileo, Brahe, Lipperhey, Janssen and Harriot for its planets. The winning names were submitted by the Royal Netherlands Association for Meteorology. They honor the astronomers Nicolaus Copernicus, Galileo Galilei, Tycho Brahe and Thomas Harriot, in 2016, the IAU organized a Working Group on Star Names to catalog and standardize proper names for stars. This star is now so entered in the IAU Catalog of Star Names,55 Cancri A has an apparent magnitude of 5.95, making it just visible to the naked eye under very dark skies. The red dwarf 55 Cancri B is of the 13th magnitude, the two components are separated by an estimated distance of 1065 AU. Despite their wide separation, the two appear to be gravitationally bound, as they share a common proper motion. The primary star,55 Cancri A, is a dwarf star of main sequence spectral type G8V. It is smaller in radius and slightly less massive than the Sun, the star has only low emission from its chromosphere, and is not variable in the visible spectrum, but it is variable in X-rays. It is more enriched than the Sun in elements heavier than helium, with 186% the solar abundance of iron and this abundance of metal makes estimating the stars age and mass difficult, as evolutionary models are less well defined for such stars. Age estimates for 55 Cancri A include 7. 4-8.7 billion years and 10.2 ±2.5 billion years, a hypothesis for the high metal content in SMR dwarf stars is that material enriched in heavy elements fell into the atmosphere from a protoplanetary disk. This would pollute the stars external layers, resulting in a higher than normal metallicity, the lack of a deep convection zone would mean that the outer layers would retain higher abundance ratios of these heavy elements. Observations of 55 Cancri A in the region of the spectrum have thus far failed to detect any associated dust
15.
Lynx (constellation)
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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
16.
Great Britain
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Great Britain, also known as Britain, is a large island in the north Atlantic Ocean off the northwest coast of continental Europe. With an area of 209,331 km2, Great Britain is the largest European island, in 2011 the island had a population of about 61 million people, making it the worlds third-most populous island after Java in Indonesia and Honshu in Japan. The island of Ireland is situated to the west of it, the island is dominated by a maritime climate with quite narrow temperature differences between seasons. Politically, the island is part of the United Kingdom of Great Britain and Northern Ireland, most of England, Scotland, and Wales are on the island. The term Great Britain often extends to surrounding islands that form part of England, Scotland, and Wales. A single Kingdom of Great Britain resulted from the union of the Kingdom of England, the archipelago has been referred to by a single name for over 2000 years, the term British Isles derives from terms used by classical geographers to describe this island group. By 50 BC Greek geographers were using equivalents of Prettanikē as a name for the British Isles. However, with the Roman conquest of Britain the Latin term Britannia was used for the island of Great Britain, the oldest mention of terms related to Great Britain was by Aristotle, or possibly by Pseudo-Aristotle, in his text On the Universe, Vol. III. To quote his works, There are two large islands in it, called the British Isles, Albion and Ierne. The name Britain descends from the Latin name for Britain, Britannia or Brittānia, Old French Bretaigne and Middle English Bretayne, Breteyne. The French form replaced the Old English Breoton, Breoten, Bryten, Breten, Britannia was used by the Romans from the 1st century BC for the British Isles taken together. It is derived from the writings of the Pytheas around 320 BC. Marcian of Heraclea, in his Periplus maris exteri, described the group as αἱ Πρεττανικαὶ νῆσοι. The peoples of these islands of Prettanike were called the Πρεττανοί, Priteni is the source of the Welsh language term Prydain, Britain, which has the same source as the Goidelic term Cruithne used to refer to the early Brythonic-speaking inhabitants of Ireland. The latter were later called Picts or Caledonians by the Romans, the Greco-Egyptian scientist Ptolemy referred to the larger island as great Britain and to Ireland as little Britain in his work Almagest. The name Albion appears to have out of use sometime after the Roman conquest of Britain. After the Anglo-Saxon period, Britain was used as a term only. It was used again in 1604, when King James VI and I styled himself King of Great Brittaine, France, Great Britain refers geographically to the island of Great Britain, politically to England, Scotland and Wales in combination
17.
Benjamin Apthorp Gould
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Benjamin Apthorp Gould was a pioneering American astronomer. He is noted for creating the Astronomical Journal, discovering the Gould Belt, and for founding of the Argentine National Observatory and he was born in Boston, Massachusetts, son of Benjamin Apthorp Gould, the principal of Boston Latin School, which the younger Gould attended. His mother was Lucretia Dana Goddard, the poet Hannah Flagg Gould was his aunt. After going on to Harvard College and graduating in 1844, he studied mathematics, gauss at Göttingen, Germany, during which time he published approximately 20 papers on the observation and motion of comets and asteroids. Following completion of his Ph. D. he toured European observatories asking for advice on what could be done to further astronomy as a science in the U. S. A. The main advice he received was to start a journal modeled after what was then the worlds leading astronomical publication. Gould returned to America in 1848 and from 1852 to 1867 was in charge of the department of the United States Coast Survey. After his return to Cambridge, Massachusetts, Gould started the Astronomical Journal in 1849 and he resumed publication in 1885 and it is still published today. In 1861 he undertook the task of preparing for publication the records of astronomical observations made at the U. S. Naval Observatory since 1850. In 1851 Gould suggested numbering asteroids in their order of discovery, in 1864 he was admitted to the Massachusetts Society of the Cincinnati to represent his grandfather Captain Benjamin Gould. In the 1890s he became a member of the Massachusetts Society of the Sons of the American Revolution. Appointed in 1862 actuary to the United States Sanitary Commission, he issued in 1869 an important volume of Military and Anthropological Statistics. In 1864 he fitted up an observatory at Cambridge, Massachusetts. In 1871 he became the first director of the Argentine National Observatory, while there, he and four assistants extensively mapped the southern hemisphere skies using newly developed photometric methods. On June 1,1884, he made the last definite sighting of the Great Comet of 1882, the need of astronomers for good weather prediction spurred Gould to collaborate with Argentine colleagues to develop the Argentine National Weather Service, the first in South America. He remained in Argentina until 1885, when he returned to Cambridge and he received the Gold Medal of the Royal Astronomical Society in 1883 and the James Craig Watson Medal in 1887. Astronomers continue to investigate the astrophysics of a large feature of the Milky Way to which he called their attention in 1877. A crater on the Moon is named after him and he died at Cambridge, Massachusetts in 1896
18.
82 G. Eridani
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82 G. Eridani is a star about 20 light years away from Earth in the constellation Eridanus. It is a star with a stellar classification of G8. In the southern-sky catalog Uranometria Argentina,82 G. Eridani is the 82nd star listed in the constellation Eridanus. The Argentina catalog, compiled by the 19th-century astronomer Benjamin Gould, is a celestial hemisphere analog of the more famous Flamsteed catalog. 82 G. Eridani, like other stars near the Sun, has held on to its Gould designation, even while other more distant stars have not. This star is smaller and less massive than the Sun, making it marginally dimmer than the Sun in terms of luminosity. The projected equatorial rotation rate is 4.0 km/s, compared to 2 km/s for the Sun, like many other Population II stars,82 G. Eridani is somewhat metal-deficient, and is older than the Sun. It has a high orbital eccentricity of 0.40 about the galaxy. Estimates of the age of this star ranged from 6 to 12 billion years and this star is located in a region of low-density interstellar matter, so it is believed to have a large astropause that subtends an angle of 6″ across the sky. Relative to the Sun, this star is moving at a velocity of 101 km/s. On August 17,2011, European astronomers announced the discovery of three planets orbiting 82 G. Eridani, the mass range of these planets classifies them as super-Earths, objects with only a few times the Earths mass. These planets were discovered by precise measurements of the velocity of the star. None of the display a significant orbital eccentricity. However, their orbital periods are all 90 days or less, the equilibrium temperature for the most distant planet, based on an assumed Bond albedo of 0.3, would be about 388 K, significantly above the boiling point of water. The number of planets in the system is slightly uncertain, at the time of planet cs detection, it exerted the lowest gravitational perturbation. There was also a similarity noted between its orbital period and the period of the star. For these reasons the team were somewhat more cautious regarding the verity of its candidate planet status than for the other two. Continued observation of the star will be required to determine the nature of the planetary system
19.
Johannes Hevelius
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Johannes Hevelius was a councillor and mayor of Danzig, then part of the Polish-Lithuanian Commonwealth. As an astronomer he gained a reputation as the founder of lunar topography and described ten new constellations, Hevelius father was Abraham Hewelke, his mother Kordula Hecker. They were German-speaking Lutherans, wealthy brewing merchants of Bohemian origin, as a young boy, Hevelius was sent to Gądecz where he studied the Polish language. Hevelius brewed the famous Jopen beer, which gave its name to the Jopengasse/Jopejska Street, after 1945 renamed as Piwna Street. In 1634 he settled in his town, and on 21 March 1635 married Katharine Rebeschke. The following year, Hevelius became a member of the beer-brewing guild, throughout his life, Hevelius took a leading part in municipal administration, becoming town councillor in 1651, but from 1639 on, his chief interest was astronomy. This may have been the longest tubed telescope before the advent of the tubeless aerial telescope, the observatory was known by the name Sternenburg or Star Castle This private observatory was visited by Polish Queen Marie Louise Gonzaga on 29 January 1660. While the noble status was not ratified by the Polish Sejm Heveliuss coat of arms includes the distinctive Polish royal crown, in May 1679 the young Englishman Edmond Halley visited him as emissary of the Royal Society, whose fellow Hevelius had been since 1664. The Royal Society considers him one of the first German fellows, małgorzata Czerniakowska writes that Jan Heweliusz was the first Pole to be inducted into the Royal Society in London. This important event took place on 19th March 1664 and he is thus considered the last astronomer to do major work without the use of a telescope. He discovered four comets, in 1652,1661,1672 and 1677 and these discoveries led to his thesis that such bodies revolve around the Sun in parabolic paths. A complex halo phenomenon was observed by many in the city on 20 February 1661, Katharine, his first wife, died in 1662, and a year later Hevelius married Elisabeth Hevelius née Koopmann, the young daughter of a merchant family. Elisabeth supported him, published two of his works after his death, and is considered the first female astronomer and his observatory, instruments and books were destroyed by fire on 26 September 1679. The catastrophe is described in the preface to his Annus climactericus and he promptly repaired the damage enough to enable him to observe the great comet of December 1680. He named the constellation Sextans in memory of these lost instruments and this constellation first occurred publicly in his star atlas Firmamentum Sobiescianum, that was printed in his own house at lavish expense, and he himself engraved many of the printing plates. His health had suffered from the shock of the 1679 fire, Hevelius was buried in St. Catherines Church in his hometown. Descendants of Hevelius live in Urzędów in Poland where they support local astronomy enthusiasts, Hevelius description of his naked eye observation method in the first part of this work led to a dispute with Robert Hooke who claimed observations without telescopic sights were of little value. Obsolete, Cerberus, Mons Maenalus, and Triangulum Minus
20.
Globular cluster
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A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes, the name of this category of star cluster is derived from the Latin globulus—a small sphere. A globular cluster is known more simply as a globular. Globular clusters are found in the halo of a galaxy and contain considerably more stars and are older than the less dense open clusters. Globular clusters are common, there are about 150 to 158 currently known globular clusters in the Milky Way. These globular clusters orbit the Galaxy at radii of 40 kiloparsecs or more, larger galaxies can have more, Andromeda Galaxy, for instance, may have as many as 500. Some giant elliptical galaxies such as M87, have as many as 13,000 globular clusters, every galaxy of sufficient mass in the Local Group has an associated group of globular clusters, and almost every large galaxy surveyed has been found to possess a system of globular clusters. The Sagittarius Dwarf galaxy and the disputed Canis Major Dwarf galaxy appear to be in the process of donating their associated globular clusters to the Milky Way and this demonstrates how many of this galaxys globular clusters might have been acquired in the past. Although it appears that globular clusters contain some of the first stars to be produced in the galaxy, their origins, the first known globular cluster, now called M22, was discovered in 1665 by Abraham Ihle, a German amateur astronomer. However, given the small aperture of early telescopes, individual stars within a cluster were not resolved until Charles Messier observed M4 in 1764. The first eight globular clusters discovered are shown in the table, subsequently, Abbé Lacaille would list NGC104, NGC4833, M55, M69, and NGC6397 in his 1751–52 catalogue. The M before a number refers to Charles Messiers catalogue, while NGC is from the New General Catalogue by John Dreyer, when William Herschel began his comprehensive survey of the sky using large telescopes in 1782 there were 34 known globular clusters. Herschel discovered another 36 himself and was the first to virtually all of them into stars. He coined the term globular cluster in his Catalogue of a Second Thousand New Nebulae, the number of globular clusters discovered continued to increase, reaching 83 in 1915,93 in 1930 and 97 by 1947. A total of 152 globular clusters have now discovered in the Milky Way galaxy. These additional, undiscovered globular clusters are believed to be hidden behind the gas, beginning in 1914, Harlow Shapley began a series of studies of globular clusters, published in about 40 scientific papers. He examined the RR Lyrae variables in the clusters and would use their period–luminosity relationship for distance estimates, later, it was found that RR Lyrae variables are fainter than Cepheid variables, which caused Shapley to overestimate the distance to the clusters. Of the globular clusters within the Milky Way, the majority are found in a halo around the core
21.
47 Tucanae
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47 Tucanae is a globular cluster located in the constellation Tucana. It is about 16,700 light years away from Earth and it can be seen with the naked eye, with a visual apparent magnitude of 4.9. Its number comes not from the Flamsteed catalogue, but the more obscure 1801 Allgemeine Beschreibung und Nachweisung der Gestirne nebst Verzeichniss compiled by Johann Elert Bode, in February 2017, indirect evidence for an intermediate-mass black hole in 47 Tucanae was announced. 47 Tucanae is the second brightest globular cluster in the sky and it is one of the most massive globular clusters in the Galaxy, containing millions of stars. The cluster appears roughly the size of the moon in the sky under ideal conditions. Though it appears adjacent to the Small Magellanic Cloud, the latter is some 210,000 light-years distant, the core of 47 Tucanae was the subject of a major survey for planets, using the Hubble Space Telescope to look for partial eclipses of stars by their planets. No planets were found, though 10-15 were expected based on the rate of planet discoveries around stars near the Sun and this indicates that planets are relatively rare in globular clusters. A later ground-based survey in the outer regions of the cluster also failed to detect planets when several were expected. This strongly indicates that the low metallicity of the environment, rather than the crowding, is responsible,47 Tucanaes dense core contains a number of exotic stars of scientific interest. Globular clusters efficiently sort stars by mass, with the most massive stars falling to the center,47 Tucanae contains at least 21 blue stragglers near its core. 47 Tucanae has 25 known millisecond pulsars, the second largest population of pulsars in any globular cluster and these pulsars are thought to be spun up by the accretion of material from binary companion stars, in a previous X-ray binary phase. It is not yet clear whether 47 Tucanae hosts a central black hole, Hubble Space Telescope data constrain the mass of any possible black hole at the clusters center to be less than approximately 1,500 solar masses. 47 Tucanae was discovered by Nicolas Louis de Lacaille in 1751 and its southern location had hidden it from European observers until then. In December 2008, Ragbir Bhathal of the University of Western Sydney claimed the detection of a strong signal from the direction of 47 Tucanae. In May 2015, the first observations of the process of mass segregation in this cluster were announced. In February 2017, the discovery of the first intermediate-mass black hole, within the globular cluster, it was found by its actions on surrounding stars. 47 Tucanae at the ESA-Hubble website 47 Tucanae, Galactic Globular Clusters Database page 47 Tucanae at the Chandra X-ray Observatory website NGC104
