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Plutoid
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be gravitationally rounded, but insufficient to achieve orbital dominance like the eight classical planets of the Solar System. The prototypical dwarf planet is Pluto, which for decades was regarded as a planet before the "dwarf" concept was adopted in 2006. Dwarf planets are capable of being geologically active, an expectation that was borne out in 2015 by the ''Dawn'' mission to and the ''New Horizons'' mission to Pluto. Planetary geologists are therefore particularly interested in them. Astronomers are in general agreement that at least the nine largest candidates are dwarf planets – in rough order of diameter, , , , , , , , , and . A considerable uncertainty remains over the tenth largest candidate , which may thus be considered a borderline case. Of these ten, two have been visited by spacecraft (Pluto and Ceres) and seven others have at least one known moon ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IAU Definition Of Planet
The International Astronomical Union (IAU) adopted in August 2006 the definition made by Uruguayan astronomers Julio Ángel Fernández and Gonzalo Tancredi that stated, that in the Solar System, a ''planet'' is a celestial body that: # is in orbit around the Sun, # has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and # has " cleared the neighbourhood" around its orbit. A non-satellite body fulfilling only the first two of these criteria (such as Pluto, which had hitherto been considered a planet) is classified as a ''dwarf planet''. According to the IAU, "planets and dwarf planets are two distinct classes of objects" – in other words, "dwarf planets" are not planets. A non-satellite body fulfilling only the first criterion is termed a '' small Solar System body'' (SSSB). An alternate proposal included dwarf planets as a subcategory of planets, but IAU members voted against this proposal. The decision was a controversial one, and has drawn both ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Possible Dwarf Planets
The number of dwarf planets in the Solar System is unknown. Estimates have run as high as 200 in the Kuiper belt and over 10,000 in the region beyond. However, consideration of the surprisingly low densities of many large trans-Neptunian objects, as well as spectroscopic analysis of their surfaces, suggests that the number of dwarf planets may be much lower, perhaps only nine among bodies known so far. The International Astronomical Union (IAU) defines dwarf planets as being in hydrostatic equilibrium, and notes six bodies in particular: in the Solar System#Inner Solar System, inner Solar System and five in the trans-Neptunian region: , , , , and . Only Pluto and Ceres have been confirmed to be in hydrostatic equilibrium, due to the results of the ''New Horizons'' and ''Dawn (spacecraft), Dawn'' missions. Eris is generally assumed to be a dwarf planet because it is similar in size to Pluto and even more massive. Haumea and Makemake were accepted as dwarf planets by the IAU for nam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pluto
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume by a small margin, but is less massive than Eris (dwarf planet), Eris. Like other Kuiper belt objects, Pluto is made primarily of ice and rock and is much smaller than the inner planets. Pluto has roughly one-sixth the mass of the Moon and one-third its volume. Originally considered a planet, its classification was changed when astronomers adopted a new definition of planet, definition of ''planet''. Pluto has a moderately Orbital eccentricity, eccentric and Inclination, inclined orbit, ranging from from the Sun. Light from the Sun takes 5.5 hours to reach Pluto at its orbital distance of . Pluto's eccentric orbit periodically brings it closer to the Sun than Neptune, but a stabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). Asteroids are rocky, metallic, or icy bodies with no atmosphere, and are broadly classified into C-type asteroid, C-type (carbonaceous), M-type asteroid, M-type (metallic), or S-type asteroid, S-type (silicaceous). The size and shape of asteroids vary significantly, ranging from small rubble piles under a kilometer across to Ceres (dwarf planet), Ceres, a dwarf planet almost 1000 km in diameter. A body is classified as a comet, not an asteroid, if it shows a coma (tail) when warmed by solar radiation, although recent observations suggest a continuum between these types of bodies. Of the roughly one million known asteroids, the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 astronomical unit, AU ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pluto And Charon Near True Color
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume by a small margin, but is less massive than Eris. Like other Kuiper belt objects, Pluto is made primarily of ice and rock and is much smaller than the inner planets. Pluto has roughly one-sixth the mass of the Moon and one-third its volume. Originally considered a planet, its classification was changed when astronomers adopted a new definition of ''planet''. Pluto has a moderately eccentric and inclined orbit, ranging from from the Sun. Light from the Sun takes 5.5 hours to reach Pluto at its orbital distance of . Pluto's eccentric orbit periodically brings it closer to the Sun than Neptune, but a stable orbital resonance prevents them from colliding. Pluto has five known moons: Charon, the larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonggong (dwarf Planet)
Gonggong (minor-planet designation: 225088 Gonggong) is a dwarf planet and a member of the scattered disc beyond Neptune. It has a highly eccentric and inclined orbit during which it ranges from from the Sun. , its distance from the Sun is , and it is the sixth-farthest known Solar System object. According to the Deep Ecliptic Survey, Gonggong is in a 3:10 orbital resonance with Neptune, in which it completes three orbits around the Sun for every ten orbits completed by Neptune. Gonggong was discovered in July 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory, and the discovery was announced in January 2009. At approximately in diameter, Gonggong is similar in size to Pluto's moon Charon, making it the fifth-largest known trans-Neptunian object (apart possibly from Charon). It may be sufficiently massive to be in hydrostatic equilibrium and therefore a dwarf planet. Gonggong's large mass makes retention of a tenuo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonzalo Tancredi
Gonzalo Tancredi (born 8 March 1963) is an Uruguayan astronomer and full professor in the Department of Astronomy at the University of the Republic in Montevideo, Uruguay. He is an active member of the International Astronomical Union (IAU) and investigator at Los Molinos Observatory. His 2010 evaluation of potential dwarf planets was considered by the IAU, though never acted on. The Themistian asteroid 5088 Tancredi has been named after him. Definition of planet In 2006, Tancredi was one of a number of dissenters at the IAU's meeting to establish the first definition of "planet. " As an alternative to the IAU's draft proposal, which had included Pluto, its moon Charon and Ceres among the planets, Tancredi with his Uruguayan colleague Julio Ángel Fernández proposed a definition where they reserved the term "planet" only for those objects in the Solar System which had cleared their neighbourhoods of planetesimals, describing those objects which had not cleared their orb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrostatic Equilibrium
In fluid mechanics, hydrostatic equilibrium, also called hydrostatic balance and hydrostasy, is the condition of a fluid or plastic solid at rest, which occurs when external forces, such as gravity, are balanced by a pressure-gradient force. In the planetary physics of Earth, the pressure-gradient force prevents gravity from collapsing the atmosphere of Earth into a thin, dense shell, whereas gravity prevents the pressure-gradient force from diffusing the atmosphere into outer space. In general, it is what causes objects in space to be spherical. Hydrostatic equilibrium is the distinguishing criterion between dwarf planets and small solar system bodies, and features in astrophysics and planetary geology. Said qualification of equilibrium indicates that the shape of the object is symmetrically rounded, mostly due to rotation, into an ellipsoid, where any irregular surface features are consequent to a relatively thin solid crust. In addition to the Sun, there are a dozen or s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mars
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from and cosmic radiation is high. Mars retains some water, in the ground as well as thinly in the atmosphere, forming cirrus clouds, frost, larger polar regions of permafrost and ice caps (with seasonal snow), but no liquid surface water. Its surface gravity is roughly a third of Earth's or double that of the Moon. It is half as wide as Earth or twice the Moon, with a diameter of , and has a surface area the size of all the dry land of Earth. Fine dust is prevalent across the surface and the atmosphere, being picked up and spread at the low Martian gravity even by the weak wind of the tenuous atmosphere. The terrain of Mars roughly follows a north-south ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vesta In Natural Color (cropped)
Vesta may refer to: Brands and products * Lada Vesta, a car from Russian car manufacturer AVTOVAZ * Swan Vesta (began 1883), a brand of matches ** Vesta case, metal containers for matches (which were previously called vestas) * Vesta, a freeze-dried meal brand launched in the United Kingdom by Batchelors in the early 1970s, and now owned by Premier Foods. Fiction and mythology * Sailor Vesta, a character in ''Sailor Moon'' * Vesta (Marvel Comics), a Marvel Comics character * Vesta (mythology), Roman goddess of the hearth and home People * Vesta Stoudt (1891–1966), factory worker during Second World War known for her letter to President Franklin D. Roosevelt suggesting the use of adhesive tape to improve ammunition boxes, leading to duct tape * Vesta (1957–2011), stage name of American recording artist Vesta Williams Music * ''Vesta'' (album), 1986 album by Vesta Williams * '' Vesta 4 U'', 1988 album by Vesta Williams * Vesta, a 2008 rock band made up of former members of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Icarus (journal)
''ICARUS'' is a scientific journal dedicated to the field of planetary science. It is officially endorsed by the American Astronomical Society's Division for Planetary Sciences (DPS). The journal contains articles discussing the results of new research on astronomy, geology, meteorology, physics, chemistry, biology, and other scientific aspects of the Solar System or extrasolar systems. The journal was founded in 1962, and became affiliated with the DPS in 1974. Its original owner and publisher was Academic Press, which was purchased by Elsevier in 2000. The journal is named for the mythical Icarus, and the frontispiece of every issue contains an extended quotation from Sir Arthur Eddington equating Icarus' adventurousness with the scientific investigator who "strains his theories to the breaking-point till the weak joints gape." Abstracting and indexing This journal is indexed by the following services: * Science Citation Index * Current Contents /Physical, Chemical & Eart ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small Solar System Bodies
A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first IAU definition of planet, defined in 2006 by the International Astronomical Union (IAU) as follows: "All other objects, except satellites, orbiting the Sun shall be referred to collectively as 'Small Solar System Bodies. (IAU) This encompasses all comets and all minor planets other than those that are dwarf planets. Thus SSSBs are: the comets; the classical asteroids, with the exception of the dwarf planet Ceres (dwarf planet), Ceres; the Trojan (astronomy), trojans; and the Centaur (minor planet), centaurs and trans-Neptunian objects, with the exception of the dwarf pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
