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Trans-Neptunian Planets In Fiction
Fictional planets of the Solar System have been depicted since the 1700s—often but not always corresponding to hypothetical planets that have at one point or another been seriously proposed by real-world astronomers, though commonly persisting in fiction long after the underlying scientific theories have been refuted. Vulcan was a planet hypothesized to exist inside the orbit of Mercury between 1859 and 1915 to explain anomalies in Mercury's orbit until Einstein's theory of general relativity resolved the matter; it continued to appear in fiction as late as the 1960s. Counter-Earth—a planet diametrically opposite Earth in its orbit around the Sun—was originally proposed by the ancient Greek philosopher Philolaus in the fifth century BCE (albeit in a pre-heliocentric framework), and has appeared in fiction since at least the late 1800s. It is sometimes depicted as very similar to Earth and other times very different, often used as a vehicle for satire, and frequently inhab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fictional Planets Of The Solar System
Fictional planets of the Solar System have been depicted since the 1700s—often but not always corresponding to List of hypothetical Solar System objects, hypothetical planets that have at one point or another been seriously proposed by real-world astronomers, though commonly persisting in fiction long after the underlying scientific theories have been refuted. Vulcan (hypothetical planet), Vulcan was a planet hypothesized to exist inside the orbit of Mercury (planet), Mercury between 1859 and 1915 to explain Perihelion precession of Mercury, anomalies in Mercury's orbit until Albert Einstein, Einstein's theory of general relativity resolved the matter; it continued to appear in fiction as late as the 1960s. Counter-Earth—a planet diametrically opposite Earth in its orbit around the Sun—was originally proposed by the Ancient Greece, ancient Greek philosopher Philolaus in the fifth century BCE (albeit in a pre-Heliocentrism, heliocentric framework), and has appeared in fiction ... [...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] |
Dwarf Planet
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, 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 (spacecraft), Dawn'' mission to and the ''New Horizons'' mission to Pluto. planetary geology, Planetary geologists are therefore particularly interested in them. Astronomers are in general agreement that at least the List of possible dwarf planets#Likeliest dwarf planets, 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 co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planet
A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets by the most restrictive definition of the term: the terrestrial planets Mercury (planet), Mercury, Venus, Earth, and Mars, and the giant planets Jupiter, Saturn, Uranus, and Neptune. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion (astrophysics), accretion. The word ''planet'' comes from the Greek () . In Classical antiquity, antiquity, this word referred to the Sun, Moon, and five points of light visible to the naked eye that moved across the background of the stars—namely, Me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reclassification Of Pluto
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 suppo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
