**********Will Pluto be reinstated as a planet?********* Pluto (minor-planet designation 134340 Pluto) is the largest object in the Kuiper belt, and the tenth-most-massive body observed directly orbiting the Sun. It is the second-most-massive known dwarf planet, after Eris. Like other Kuiper-belt objects, Pluto is composed primarily of rock and ice and is relatively small, approximately one-sixth the mass of the Moon and one-third its volume. It has an eccentric and highly inclined orbit that takes it from 30 to 49 AU (4.4–7.4 billion km) from the Sun. This causes Pluto to periodically come closer to the Sun than Neptune, but an orbital resonance with Neptune prevents the bodies from colliding. , but an orbital resonance with Neptune prevents the bodies from colliding .Pluto has five known moons: Charon (the largest, with a diameter just over half that of Pluto), Nix, Hydra, Kerberos, and Styx.Pluto and Charon are sometimes described as a binary system because the barycenter of their orbits does not lie within either body. The IAU has yet to formalise a definition for binary dwarf planets, and Charon is officially classified as a moon of Pluto.But back in 2006, the International Astronomical Union (IAU), arbiter of what is and what isn’t a planet, stripped Pluto of its status, saying it was too small to pack sufficient gravitational punch. It was downgraded to a new, second-class status: “dwarf planet.” In 2014 it was 32.6 AU from the Sun,The debate centered around the IAU’s demands of a planet —* that it must:be in orbit around the Sun,*be round or nearly round, and be shown to have “cleared the neighborhood” around its orbit, *be gravitationally dominant in its area — the big kid on the block.Pluto was originally kicked out because it did not “clear the neighborhood.” It is indeed small. It has a radius of about 750 miles — less than 20 per cent of the Earth’s radius. Its circumference is about 4,500 miles, which makes it smaller than the moon.
Posted on: Sun, 05 Oct 2014 09:12:34 +0000
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