why is pluto not a dwarf planet?
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The International Astronomical Union (IAU) downgraded the status of Pluto to that of a dwarf planet because it did not meet the three criteria the IAU uses to define a full-sized planet. Essentially Pluto meets all the criteria except one—it “has not cleared its neighboring region of other objects.”
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Pluto's surface is composed of a mixture of frozen nitrogen, methane, and carbon monoxide ices. The dwarf planet also has polar caps and regions of frozen methane and nitrogen. Pluto has three known moons, Hydra, Nix, and Charon.
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Pluto was discovered by Clyde Tombaugh in 1930 and was originally considered to be the ninth planet from the Sun. After 1992, its status as a planet was questioned following the discovery of several objects of similar size in the Kuiper belt. ... That definition excluded Pluto and reclassified it as a dwarf planet.
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(2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,2 (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
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Ever since the discovery of Pluto in 1930, kids grew up learning that the solar system has nine planets. That all changed in the late 1990s, when astronomers started arguing about whether Pluto was indeed a planet.
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Is Pluto a Dwarf Planet? Because it has not cleared the neighborhood around its orbit, Pluto is considered a dwarf planet. It orbits in a disc-like zone beyond the orbit of Neptune called the Kuiper belt, a distant region populated with frozen bodies left over from the solar system's formation.
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Gas giants consist of a small rocky core with an outer liquid layer, surrounded by a deep gaseous atmosphere. By contrast, Pluto's structure is at least half rock, surrounded by a layer of deep ice.
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Dwarf planets So, the reason that many books say that Pluto is a planet, is because for 76 years that was true. Everyone over age 30 knew Pluto as a planet for more than half their lifetimes. In 2015, the New Horizons space probe flew past Pluto, taking the highest resolution pictures ever of the dwarf planet.
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Our moon is hence a moon. No, but only because it orbits us. The only difference between a planet and a dwarf planet is the area surrounding each celestial body. ... Since the new definition, three objects in our solar system have been classified as dwarf planets: Pluto, Ceres and Eris.
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There are 5 officially recognised dwarf planets in our solar system, they are Ceres, Pluto, Haumea, Makemake and Eris. With the exception of Ceres, which is located in the asteroid belt, the other dwarf planets are found in the outer solar system.
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A dwarf planet, by IAU's new definition, must directly orbit the Sun. It must be massive enough for gravity to pull it into a roughly spherical shape. But unlike regular planets, dwarf planets haven't cleared other smaller celestial debris out of its orbital path.
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This led the International Astronomical Union (IAU) to define the term "planet" formally in 2006, during their 26th General Assembly. That definition excluded Pluto and reclassified it as a dwarf planet. It is the ninth-largest and tenth-most-massive known object directly orbiting the Sun.
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Dwarf Planets. Dwarf planets are objects in the solar system which orbit the Sun. ... Unlike planets, they have not cleared their orbits, meaning that there could be several or many dwarf planets orbiting the Sun at the same distance and in the same plane. Satellites of planets are not considered dwarf planets.
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When Pluto was discovered 80 years ago, we never could have expected the variety of objects in the Solar System. Categorizing Pluto as a dwarf planet helps us better describe our celestial home. So, our Solar System now has eight planets, and five dwarf planets.
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The International Astronomical Union (IAU) downgraded the status of Pluto to that of a dwarf planet because it did not meet the three criteria the IAU uses to define a full-sized planet. ... It contains the asteroid belt as well as the terrestrial planets, Mercury, Venus, Earth, and Mars.
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Pluto is composed of a large rocky core wrapped in thick layers of ices. Its icy surface and extremely thin atmosphere are predominantly composed of nitrogen with small amounts of methane and carbon monoxide. The terrain shows remarkable variation including dark/bright regions and smooth/mountainous areas.
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In August 2006 the International Astronomical Union (IAU) downgraded the status of Pluto to that of “dwarf planet.” This means that from now on only the rocky worlds of the inner Solar System and the gas giants of the outer system will be designated as planets.