Learn about the solar system and the dwarf planet of Pluto.
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Male Speaker: Because of the fact of Pluto was considered a planet for most of the 20th Century. We've decided to throw it in honorable mention. In 2006 the international astronomical union officially define what a planet is leaving Pluto out, the new definition does made it Pluto as a fourth planet, in recent years discoveries have been made specifically of a Ares which was larger than Pluto, this ignited at the at the bay, on what made a planet officially a planet. It is extremely difficult to study Pluto because of its extremely small size, and the fact that it is so far from earth. Pluto's diameter is only 19% of the size of a earth, NASA's new varizon to it was launched in 2006 and it is expected to reach its closest point to Pluto in 2015, Pluto has 3 natural satellites, one was discovered in 1978, or the other two nets in the Hydra were not discovered until 2005.