PLUTO

Pluto is the ninth dwarf planet from the Sun. Little is know about Pluto,which is the smallest planet in the Solar System. It is realy cold,rocky body with a moon that is nearly half the size of the planet it self. It takes Pluto 248 years to orbit the Sun once. For many years, Pluto was thought of as the farthest known planet from the Sun. It has a very unusual orbit. Once every 248 Earth years, Pluto swings inside the orbit of Neptune. It stays there for twenty years. During those twenty years, Pluto is closer to the Sun than Neptune.

Pluto was discovered in 1930 as a result of an extensive search by astronomer Clyde Tombaugh. Some astronomers have long argued that Pluto's small size, less than one-fifth the diameter of Earth, and a weird tilted orbit that takes it inside Neptune every couple hundred years make Pluto more like a Kuiper Belt body than a full-fledged planet. On August 24, 2006, the International Astronomical Union passed a new definition of planet that excludes Pluto and puts it in a new category of "dwarf planet."