Why+Pluto?

=Why is Pluto not a planet?= Pluto isn't a planet anymore. This is because it is part of the Kuiper Belt, which is a group of large icy bodies. At first scientists only knew of Pluto, and not the Kuiper belt. But as more and more small bodies like pluto were discovered, they began to doubt wether pluto and these were all planets. Astronomers then had to come up with a formal definition of the word planet. That new definition said that the object must be large enough to clear it's orbital path of space debris such as asteroids, meteors, and comets. After the definition was added Pluto and the rest of the Kuiper Belt objects were demoted to dwarve planets.

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