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Dark Horse (astronomy)
The Dark Horse Nebula or Great Dark Horse (sometimes called the Prancing Horse) is a large dark nebula that, from Earth's perspective, obscures part of the upper central bulge of the Milky Way. The Dark Horse lies in the equatorial constellation Ophiuchus (the Serpent Bearer), near its borders with the more famous constellations Scorpius and Sagittarius. It is a large, visible feature of the Milky Way's Great Rift, uniting several individually catalogued dark nebulae, including the Pipe Nebula. It is visible from Earth only on clear moonless nights without light pollution and with low humidity. Name This region of dark nebulae is called Dark Horse because it resembles the side silhouette of a horse and appears dark as compared with the background glow of stars and star clouds. It is also known as "Great" because it is one of the largest (in apparent size) groups of dark nebulae in the sky. Nearby nebulae The rear of the Great Dark Horse (its rump and hind legs), is also know ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 (one million million, or billion in long scale). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the time-measurement word "year", the term ''light-year'' is sometimes 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) which derives from astrometry; it is the distance at which one astronomical unit subtends an angle of one second of arc. Defini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth & Sky
''Earth & Sky'' was a daily radio series that presented information about science and nature. It began broadcasting in 1991 and ceased operations in 2013. ''EarthSky'' is the ongoing website, serving 21 million users in 2019, according to Google Analytics. ''Earth & Sky'' was the creation of producers Deborah Byrd and Joel Block, who were also the hosts. Byrd had previously created the radio program '' Star Date'' that began broadcasting in the US in 1978, and Block was ''Star Dates original host. ''Earth & Sky'' presented 60- and 90-second radio spots (called "modules") on a wide variety of scientific topics, communicating through terrestrial radio as well as satellite radio and internet radio. ''Earth & Sky'' was aired one or more times daily on more than 1,000 commercial, NPR, and other public radio stations, 80 affiliate stations for the sight-impaired, and across 35 channels on both XM and Sirius satellite radio in the United States. Abroad, the programming iwas heard o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coalsack Nebula
The Coalsack Nebula (Southern Coalsack, or simply the Coalsack) is a prominent dark nebula in the skies, being easily visible to the naked eye as a dark patch obscuring a brief section of Milky Way stars as they cross their southernmost region of the sky, east of Acrux (Alpha Crucis) which is the bright, southern pointer star of the southern cross. It dominates and overspills the southeast corner of what is considered the extent of the constellation Crux at a little less than twice the distance of Acrux, away from Earth. General information The Coalsack Nebula covers nearly 7 ° by 5° and overlaps somewhat with the neighbor constellations Centaurus and Musca. The first observation was reported by Vicente Yáñez Pinzón in 1499. It was named "''il Canopo fosco''" (the dark Canopus) by Amerigo Vespucci and was also called "''Macula Magellani''" (Magellan's Spot) or "''Black Magellanic Cloud''" in opposition to the Magellanic Clouds. The Coalsack is omitted in most of today's sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barnard 68
Barnard 68 is a molecular cloud, dark absorption nebula or Bok globule, towards the southern constellation Ophiuchus and well within the Milky Way galaxy at a distance of about 500 light-years, so close that not a single star can be seen between it and the Sun. American astronomer Edward Emerson Barnard added this nebula to his catalog of dark nebulae in 1919. His catalog was published in 1927, at which stage it included some 350 objects. Because of its opacity, its interior is extremely cold, its temperature being about 16 K (−257 °C/-431 °F). Its mass is about twice that of the Sun and it measures about half a light-year across. Characteristics Despite being opaque at visible-light wavelengths, use of the Very Large Telescope at Cerro Paranal has revealed the presence of about 3,700 blocked background Milky Way stars, some 1,000 of which are visible at infrared wavelengths. Careful measurements of the degree of obscuration resulted in a finely sampled and acc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snake Nebula
The Snake Nebula (also known as Barnard 72) is a dark nebula in the Ophiuchus, Ophiuchus constellation. It is a small but readily apparent SP-shaped dust lane that snakes out in front of the Milky Way star clouds from the north-north-west edge of the bowl of the Pipe Nebula. Its thickness runs between 2′ and 3′ and runs around 6′ in the north-west / south-east orientation. A good view in a 4" to 6" telescope requires clear dark skies. It is part of the much larger Dark Horse (astronomy), Dark Horse Nebula. To the right of the Snake Nebula is Barnard 68. Below it is Barnard 69, Barnard 70, and Barnard 74. External links * * {{Cite APOD , date=20 February 2009, title=Snake in the Dark Dark nebulae Barnard objects Ophiuchus (constellation) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barnard Catalogue
The astronomer Edward Emerson Barnard compiled a list of dark nebulae known as the ''Barnard Catalogue of Dark Markings in the Sky'', or the ''Barnard Catalogue'' for short. The nebulae listed by Barnard have become known as Barnard objects. A 1919 version of the catalogue listed 182 nebulae; by the time of the posthumously published 1927 version, it listed 369. See also * List of dark nebulae References barnard Astronomical catalogues of nebulae External links Barnard's Catalogue of 349 Dark Objects in the Sky VizieR A vizier (; ar, وزير, wazīr; fa, وزیر, vazīr), or wazir, is a high-ranking political advisor or minister in the near east. The Abbasid caliphs gave the title ''wazir'' to a minister formerly called '' katib'' (secretary), who was ... listing at CDS {{astronomical-catalogue-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barnard 59
Barnard is a version of the surname Bernard, which is a French and West Germanic masculine given name and surname. The surname means as tough as a bear, Bar(Bear)+nard/hard(hardy/tough) __NOTOC__ People Some of the people bearing the surname Barnard in England are thought to have arrived after the time of the Norman Conquest (1066), Changing their surnames from Bernard to Barnard. Some of whom, it has been suggested, can be traced back to Hugo Bernard. Some of the Barnard family in England may have been Huguenots who fled from the Atlantic coast region of France ''circa'' 1685 (the time of the revocation of the edict of Nantes) or earlier than that date. By contrast, the Barnard family in Holland (the western provinces of the Netherlands) can be definitively traced back to ''circa'' 1751 (Izaak Barnard) of Scheveningen.The surname Barnard is also found in South Africa among the Afrikaner community. An example of this is Christiaan Barnard, A South African Cardiac Surgeon who p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barnard 78
Barnard is a version of the surname Bernard, which is a French and West Germanic masculine given name and surname. The surname means as tough as a bear, Bar(Bear)+nard/hard(hardy/tough) __NOTOC__ People Some of the people bearing the surname Barnard in England are thought to have arrived after the time of the Norman Conquest (1066), Changing their surnames from Bernard to Barnard. Some of whom, it has been suggested, can be traced back to Hugo Bernard. Some of the Barnard family in England may have been Huguenots who fled from the Atlantic coast region of France ''circa'' 1685 (the time of the revocation of the edict of Nantes) or earlier than that date. By contrast, the Barnard family in Holland (the western provinces of the Netherlands) can be definitively traced back to ''circa'' 1751 (Izaak Barnard) of Scheveningen.The surname Barnard is also found in South Africa among the Afrikaner community. An example of this is Christiaan Barnard, A South African Cardiac Surgeon who ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barnard 77
Barnard is a version of the surname Bernard, which is a French and West Germanic masculine given name and surname. The surname means as tough as a bear, Bar(Bear)+nard/hard(hardy/tough) __NOTOC__ People Some of the people bearing the surname Barnard in England are thought to have arrived after the time of the Norman Conquest (1066), Changing their surnames from Bernard to Barnard. Some of whom, it has been suggested, can be traced back to Hugo Bernard. Some of the Barnard family in England may have been Huguenots who fled from the Atlantic coast region of France ''circa'' 1685 (the time of the revocation of the edict of Nantes) or earlier than that date. By contrast, the Barnard family in Holland (the western provinces of the Netherlands) can be definitively traced back to ''circa'' 1751 (Izaak Barnard) of Scheveningen.The surname Barnard is also found in South Africa among the Afrikaner community. An example of this is Christiaan Barnard, A South African Cardiac Surgeon who per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Size
The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is the angular aperture (of a lens). The angular diameter can alternatively be thought of as the angular displacement through which an eye or camera must rotate to look from one side of an apparent circle to the opposite side. Humans can resolve with their naked eyes diameters of up to about 1 arcminute (approximately 0.017° or 0.0003 radians). This corresponds to 0.3 m at a 1 km distance, or to perceiving Venus as a disk under optimal conditions. Formula The angular diameter of a circle whose plane is perpendicular to the displacement vector between the point of view and the center of said circle can be calculated using the formula :\delta = 2\arctan \left(\frac\right), in which \delta is the angular diameter, and d is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Cloud
Star clusters are large groups of stars. Two main types of star clusters can be distinguished: globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound, while open clusters are more loosely clustered groups of stars, generally containing fewer than a few hundred members, and are often very young. Open clusters become disrupted over time by the gravitational influence of giant molecular clouds as they move through the galaxy, but cluster members will continue to move in broadly the same direction through space even though they are no longer gravitationally bound; they are then known as a stellar association, sometimes also referred to as a ''moving group''. Star clusters visible to the naked eye include the Pleiades, Hyades, and 47 Tucanae. Open cluster Open clusters are very different from globular clusters. Unlike the spherically distributed globulars, they are confined to the galactic plane, and are almost always found withi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its 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, but 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 composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Its stellar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
