Pluto

Pluto is the ninth planet of the solar system. It was discovered in 1930 and immediately classified as a planet. This status is disputed by some.[1] Pluto has an eccentric orbit that is highly inclined with respect to the other planets and takes it inside the orbit of Neptune. Its largest moon is Charon, discovered in 1978; two smaller moons were discovered in 2005. Pluto's astronomical symbol is a P-L monogram, ♇. This represents both the first two letters of the name Pluto and the initials of Percival Lowell, the man who lent his name to the observatory that was used to find Pluto. An alternate symbol resembles that of Neptune (♆), but has a circle in place of the middle spoke in the top center. New Horizons, which lifted off from Cape Canaveral, Florida on January 19, 2006, is expected to become the first unmanned spacecraft to perform a flyby and observation of Pluto on July 14, 2015.

Due to its size and unusual orbit, there has been debate regarding Pluto's classification as a major or a minor planet, and there is increasing momentum for recognizing "dual status." Pluto is classified as a trans-Neptunian object. As of July 31, 2005, one other trans-Neptunian object, 2003 UB313, had been found that is larger than Pluto.