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Pluto: Overview
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Color image of Pluto and its Moons.
A Hubble Space Telescope image of Pluto and its moons. Charon is the largest moon close to Pluto. The other four bright dots are smaller moons discovered in 2005, 2011 and 2012.

Discovered in 1930, Pluto was long considered our solar system's ninth planet. But after the discovery of similar intriguing worlds deeper in the distant Kuiper Belt, icy Pluto was reclassified as a dwarf planet. This new class of worlds may offer some of the best evidence about the origins of our solar system. Pluto is also a member of a group of objects that orbit in a disc-like zone beyond the orbit of Neptune called the Kuiper Belt. This distant realm is populated with thousands of miniature icy worlds, which formed early in the history of our solar system. These icy, rocky bodies are called Kuiper Belt objects or transneptunian objects.

Featured Mission: New Horizons
NASA's New Horizons will be the first spacecraft to visit Pluto and the Kuiper Belt. The spacecraft's nine and a half year journey to the ice dwarf began in January 2006. The spacecraft will reach Pluto in 2015.

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Just the Facts
Orbit Size (semi-major axis):  5,906,440,628 km
Mean Radius:  1,151 km
Volume:  6,387,259,783 km3
Mass:  13,090,000,000,000,000,000,000 kg
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Mihaly Horanyi Mihaly Horanyi
"I study cosmic dust, and dusty plasmas in space and in the laboratory." Read More...
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Last Updated: 14 Mar 2014