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Alcor (star)
Alcor () is a binary star system in the constellation of Ursa Major. It is the fainter companion of Mizar, the two stars forming a naked eye double in the handle of the Big Dipper (or Plough) asterism in Ursa Major. The two lie about 83 light-years away from the Sun, as measured by the ''Hipparcos'' astrometry satellite. Nomenclature Alcor has the Flamsteed designation ''80 Ursae Majoris''. ''Alcor'' derives from Arabic , meaning 'faint one';List of Arabic star names, published in ''Popular Astronomy'', January 1895, by Professor Robert H. West, of the Syrian Protestant College at Beirut. notable as a faintly perceptible companion of Mizar. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included ''Alcor'' for 80 UMa. Mizar and Alcor With normal eyesight ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mizar (star)
Mizar is a second-apparent magnitude, magnitude star in the handle of the Big Dipper Asterism (astronomy), asterism in the constellation of Ursa Major. It has the Bayer designation ζ Ursae Majoris (Latinisation of names, Latinised as Zeta Ursae Majoris). It forms a well-known naked eye double star with the fainter star Alcor (star), Alcor (a binary system consisting of Alcor A and Alcor B), and is itself a Star system, quadruple star system. The Mizar and Alcor, Mizar and Alcor system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite, and is part of the Ursa Major Moving Group. Nomenclature ''ζ Ursae Majoris'' (Latinisation of names, Latinised to ''Zeta Ursae Majoris'' and abbreviated to ζ UMa or Zeta UMa) is Mizar's Bayer designation. It also has the Flamsteed designation 79 Ursae Majoris. The traditional name ''Mizar'' derives from the Arabic ' ' meaning 'apron; wrapper, covering, cover'. In 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star
A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sky, night; their immense distances from Earth make them appear as fixed stars, fixed points of light. The most prominent stars have been categorised into constellations and asterism (astronomy), asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye—all within the Milky Way galaxy. A star's life star formation, begins with the gravitational collapse of a gaseous nebula of material largely comprising hydrogen, helium, and traces of heavier elements. Its stellar mass, total mass mainly determines it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dipper
Dippers are members of the genus ''Cinclus'' in the bird family Cinclidae, so-called because of their bobbing or dipping movements. They are unique among passerines for their ability to dive and swim underwater. Taxonomy The genus ''Cinclus'' was introduced by the German naturalist Moritz Balthasar Borkhausen in 1797 with the white-throated dipper (''Cinclus cinclus'') as the type species. The name ''cinclus'' is from the Ancient Greek word ''kinklos'' that was used to describe small tail-wagging birds that resided near water. ''Cinclus'' is the only genus in the family Cinclidae. The white-throated dipper and American dipper are also known in Britain and America, respectively, as the ''water ouzel'' (sometimes spelt "ousel") – ouzel originally meant the only distantly related but superficially similar Eurasian blackbird (Old English ''osle''). Ouzel also survives as the name of a relative of the blackbird, the ring ouzel. The genus contains five species: * White-throa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Working Group On Star Names
The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education, Outreach and Heritage. The IAU states that it is keen to make a distinction between the terms ''name'' and ''designation''. To the IAU, ''name'' refers to the (usually colloquial) term used for a star in everyday conversation, while ''designation'' is solely alphanumerical, and used almost exclusively in official catalogues and for professional astronomy. (The WGSN notes that transliterated Bayer designations (e.g., Tau Ceti) are considered a special historical case and are treated as designations.) Terms of reference The terms of reference for the WGSN for the period 2016–2018 were approved by the IAU Executive Committee at its meeting on 6 May 2016. In summary, these are to: * establish IAU guidelines for the proposal and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Astronomical Union
The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation. It was founded on 28 July 1919 in Brussels, Belgium and is based in Paris, France. The IAU is composed of individual members, who include both professional astronomers and junior scientists, and national members, such as professional associations, national societies, or academic institutions. Individual members are organised into divisions, committees, and working groups centered on particular subdisciplines, subjects, or initiatives. the Union had 85 national members and 12,734 individual members, spanning 90 countries and territories. Among the key activities of the IAU is serving as a forum for scientific conferences. It sponsors nine annual symposia and holds a triannual General Assembly that sets policy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mizar
Mizar is a second-magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major. It has the Bayer designation ζ Ursae Majoris ( Latinised as Zeta Ursae Majoris). It forms a well-known naked eye double star with the fainter star Alcor (a binary system consisting of Alcor A and Alcor B), and is itself a quadruple star system. The Mizar and Alcor system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite, and is part of the Ursa Major Moving Group. Nomenclature ''ζ Ursae Majoris'' ( Latinised to ''Zeta Ursae Majoris'' and abbreviated to ζ UMa or Zeta UMa) is Mizar's Bayer designation. It also has the Flamsteed designation 79 Ursae Majoris. The traditional name ''Mizar'' derives from the Arabic ' ' meaning 'apron; wrapper, covering, cover'. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper name ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabic Star Names
This is a list of Arabic star names. In Western astronomy, most of the accepted star names are Arabic, a few are Greek and some are of unknown origin. Typically only bright stars have names. History of Arabic star names Very old star names originated among people who lived in the Arabian Peninsula more than a thousand years ago, after the rise of Islam. However, some Arabic language star names sprang up later in history, as translations of ancient Greek language descriptions. The astronomer Claudius Ptolemy in his ''Almagest'' (2nd century) tabulated the celestial position and brightness (visual magnitude) of 1,025 stars. Ptolemy's book was translated into Arabic in the 8th and 9th centuries and became famous in Europe as a 12th-century Latin translation. Many of the Arabic-language star descriptions in the ''Almagest'' came to be widely used as names for stars. Ptolemy used a strategy of "figure reference" to identify stars according to their position within a familiar conste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabic
Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns language codes to 32 varieties of Arabic, including its standard form of Literary Arabic, known as Modern Standard Arabic, which is derived from Classical Arabic. This distinction exists primarily among Western linguists; Arabic speakers themselves generally do not distinguish between Modern Standard Arabic and Classical Arabic, but rather refer to both as ( "the eloquent Arabic") or simply ' (). Arabic is the List of languages by the number of countries in which they are recognized as an official language, third most widespread official language after English and French, one of six official languages of the United Nations, and the Sacred language, liturgical language of Islam. Arabic is widely taught in schools and universities around the wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrometry
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other Astronomical object, celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. History The history of astrometry is linked to the history of star catalogues, which gave astronomers reference points for objects in the sky so they could track their movements. This can be dated back to the ancient Greek astronomer Hipparchus, who around 190 BC used the catalogue of his predecessors Timocharis and Aristillus to discover Earth's precession. In doing so, he also developed the brightness scale still in use today. Hipparchus compiled a catalogue with at least 850 stars and their positions. Hipparchus's successor, Ptolemy, included a catalogue of 1,022 stars in his work the ''Almagest'', giving their location, coordinates, and brightness. In the 10th century, the Iranian astronomer Abd al-Rahman al-Sufi carried ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hipparcos
''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions and distances of celestial objects on the sky. This permitted the first high-precision measurements of the intrinsic brightnesses, proper motions, and parallaxes of stars, enabling better calculations of their distance and tangential velocity. When combined with radial velocity measurements from spectroscopy, astrophysicists were able to finally measure all six quantities needed to determine the motion of stars. The resulting ''Hipparcos Catalogue'', a high-precision catalogue of more than 118,200 stars, was published in 1997. The lower-precision ''Tycho Catalogue'' of more than a million stars was published at the same time, while the enhanced Tycho-2 Catalogue of 2.5 million stars was published in 2000. ''Hipparcos'' follow-up mission, '' Gaia'', was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light-year
A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year (365.25 days). Despite its inclusion of the word "year", the term should not be misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years). Definitions As defined by the International Astronomical Union (IAU), the light-year is the product of the Julian year (365.25 days, as opposed to the 365.2425-day Gregorian year or the 365.24219-day Tropical year that both approxim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterism (astronomy)
An asterism is an observational astronomy, observed pattern or group of stars in the sky. Asterisms can be any identified star pattern, and therefore are a more general concept than the IAU designated constellations, 88 formally defined constellations. Constellations are based upon asterisms, but unlike asterisms, constellations are defined regions with official boundaries which together encompass the entire sky. Asterisms range from simple shapes of just a few stars to more complex collections of many stars covering large portions of the sky. The stars themselves may be bright naked-eye objects or fainter, even telescopic, but they are generally all of a similar brightness to each other. The larger brighter asterisms are useful for people who are familiarizing themselves with the night sky. The patterns of stars seen in asterisms are not necessarily a product of any physical association between the stars, but are rather the result of the particular perspectives of their observ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
