|
California Nebula
The California Nebula ( NGC 1499/ Sh2-220) is an emission nebula located in the constellation Perseus. Its name comes from its resemblance to the outline of the US State of California in long exposure photographs. It is almost 2.5° long on the sky and, because of its very low surface brightness, it is extremely difficult to observe visually. It can be observed with a H''α'' filter (isolates the H''α'' line at 656 nm) or H''β'' filter (isolates the H''β'' line at 486 nm) in a rich-field telescope under dark skies. It lies at a distance of about 1,000 light years from Earth. Its fluorescence is due to excitation of the H''β'' line in the nebula by the nearby prodigiously energetic O7 star, Xi Persei (also known as Menkib). The California Nebula was discovered by E. E. Barnard in 1884. By coincidence, the California Nebula transits in the zenith in central California as the latitude matches the declination of the object. NASA selected the California Nebula as its As ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degree (angle)
A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol), is a measurement of a plane (mathematics), plane angle in which one Turn (geometry), full rotation is 360 degrees. It is not an SI unit—the SI unit of angular measure is the radian—but it is mentioned in the SI Brochure, SI brochure as an Non-SI units mentioned in the SI, accepted unit. Because a full rotation equals 2 radians, one degree is equivalent to radians. History The original motivation for choosing the degree as a unit of rotations and angles is unknown. One theory states that it is related to the fact that 360 is approximately the number of days in a year. Ancient astronomers noticed that the sun, which follows through the ecliptic path over the course of the year, seems to advance in its path by approximately one degree each day. Some ancient calendars, such as the Iranian calendar, Persian calendar and the Babylonian calendar, used 360 days for a year. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface is made up of the ocean, dwarfing Earth's polar ice, lakes, and rivers. The remaining 29% of Earth's surface is land, consisting of continents and islands. Earth's surface layer is formed of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates the magnetic field that shapes the magnetosphere of the Earth, deflecting destructive solar winds. The atmosphere of the Earth consists mostly of nitrogen and oxygen. Greenhouse gases in the atmosphere like carbon dioxide (CO2) trap a part of the energy from the Sun close to the surface. Water vapor is widely present in the atmosphere and forms clouds that cover most of the planet. More solar e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emission Nebulae
An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emission nebulae are H II regions, in which star formation is taking place and young, massive stars are the source of the ionizing photons; and planetary nebulae, in which a dying star has thrown off its outer layers, with the exposed hot core then ionizing them. General information Usually, a young star will ionize part of the same cloud from which it was born, although only massive, hot stars can release sufficient energy to ionize a significant part of a cloud. In many emission nebulae, an entire cluster of young stars is contributing energy. Stars that are cooler than around 25,000K don't give off enough ultraviolet radiation with wavelengths shorter than 91.2nm (the wavelength needed in order to ionize Hydrogen atoms). This results in the re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC Objects
The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and emission nebulae. Dreyer published two supplements to the NGC in 1895 and 1908, known as the ''Index Catalogues'' (abbreviated IC), describing a further 5,386 astronomical objects. Thousands of these objects are best known by their NGC or IC numbers, which remain in widespread use. The NGC expanded and consolidated the cataloguing work of William and Caroline Herschel, and John Herschel's ''General Catalogue of Nebulae and Clusters of Stars''. Objects south of the celestial equator are catalogued somewhat less thoroughly, but many were included based on observation by John Herschel or James Dunlop. The NGC contained multiple errors, but attempts to eliminate them were made by the ''Revised New General Catalogue'' (RNGC) by Jack W. Sulenti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wide-field Infrared Survey Explorer
Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 2011, before being re-activated in 2013 and renamed the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE). WISE discovered thousands of minor planets and numerous star clusters. Its observations also supported the discovery of the first Y-type brown dwarf and Earth trojan asteroid. WISE performed an all-sky astronomical survey with images in 3.4, 4.6, 12 and 22 μm wavelength range bands, over ten months using a diameter infrared telescope in Earth orbit. After its solid hydrogen coolant depleted, a four-month mission extension called NEOWISE was conducted to search for near-Earth objects (NEO) such as comets and asteroids using its remaining capability. The WISE All-Sky (WISEA) data, including processed images, source cat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Emerson Barnard
Edward Emerson Barnard (December 16, 1857 – February 6, 1923) was an American astronomer. He was commonly known as E. E. Barnard, and was recognized as a gifted observational astronomer. He is best known for his discovery of the high proper motion of Barnard's Star in 1916, which is named in his honor. Early life Barnard was born in Nashville, Tennessee, to Reuben Barnard and Elizabeth Jane Barnard (''née'' Haywood), and had one brother. His father died three months before his birth, so he grew up in an impoverished family and did not receive much in the way of formal education. His first interest was in the field of photography, and he became a photographer's assistant at the age of nine. He later developed an interest in astronomy. In 1876 he purchased a refractor telescope, and in 1881 he discovered his first comet, but failed to announce his discovery. He found his second comet later the same year and a third in 1882. While he was still working at a photography studio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopedia Of Science
David Darling (born 29 July 1953 in Glossop, Derbyshire) is an English astronomer, freelance science writer, and musician. Darling has published numerous popular science works, including ''Life Everywhere: The Maverick Science of Astrobiology'' in 2001 and ''The Universal Book of Mathematics ''The Universal Book of Mathematics: From Abracadabra to Zeno's Paradoxes'' (2004) is a bestselling book by British author David Darling. Summary The book is presented in a dictionary format. The book is divided into headwords, which, as the ti ...'' in 2004. He maintains the online ''Internet Encyclopedia of Science''. A review of Darling's book ''Soul Search'', stated that "he develops a sort of scientific pantheism positing that, with death, we move from the narrow consciousness of our highly selective, reality-filtering brain to the wider, timeless consciousness of the unbound universe." [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xi Persei
Xi Persei (ξ Persei, abbreviated Xi Per, ξ Per), known also as Menkib , is a star in the constellation of Perseus (constellation), Perseus. Based upon stellar parallax, parallax measurements taken during the Hipparcos mission, it is approximately 1,200 light-years from the Sun. Nomenclature ''ξ Persei'' (Latinisation of names, Latinised to ''Xi Persei'') is the star's Bayer designation. It bore the traditional name ''Menkib'', ''Menchib'', ''Menkhib'' or ''Al Mankib'', from ''Mankib al Thurayya'' (Arabic for "shoulder" [of the Pleiades]). In 2016, the International Astronomical Union (IAU) organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name ''Menkib'' for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names. In Chinese astronomy, Chinese, (), meaning ''Hairy Head, Rolled Tongue'', refers to an asterism (astronomy), asterism consisting of Xi Persei, Nu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xi Persei
Xi Persei (ξ Persei, abbreviated Xi Per, ξ Per), known also as Menkib , is a star in the constellation of Perseus (constellation), Perseus. Based upon stellar parallax, parallax measurements taken during the Hipparcos mission, it is approximately 1,200 light-years from the Sun. Nomenclature ''ξ Persei'' (Latinisation of names, Latinised to ''Xi Persei'') is the star's Bayer designation. It bore the traditional name ''Menkib'', ''Menchib'', ''Menkhib'' or ''Al Mankib'', from ''Mankib al Thurayya'' (Arabic for "shoulder" [of the Pleiades]). In 2016, the International Astronomical Union (IAU) organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name ''Menkib'' for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names. In Chinese astronomy, Chinese, (), meaning ''Hairy Head, Rolled Tongue'', refers to an asterism (astronomy), asterism consisting of Xi Persei, Nu ... [...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] |
Perseus (constellation)
Perseus is a constellation in the Northern celestial hemisphere, northern sky, being named after the Greek mythology, Greek mythological hero Perseus. It is one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy, and among the IAU designated constellations, 88 modern constellations defined by the International Astronomical Union (IAU). It is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda (constellation), Andromeda to the west and Cassiopeia (constellation), Cassiopeia to the north. Perseus is also bordered by Aries (constellation), Aries and Taurus (constellation), Taurus to the south, Auriga (constellation), Auriga to the east, Camelopardalis to the north, and Triangulum to the west. Some Celestial cartography, star atlases during the early 19th century also depicted Perseus holding the disembodied head of Medusa, whose Asterism (astronomy), asterism was named together as ''Perseus e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.svg "Click for more on -> Earth")
