Everything that orbits a Star is not a planet. For instance we do not deem the moon as a planet as it is one of Earth's satellites. Just like Earth (A true planet) has satellites as does the sun that are a very large distance out. Pluto is a dwarf planet along with the asteroids and other dwarf planets in the Kuiper Belt. (Plutos true home) Pluto is too un-unique and too distanced from the larger planets that orbit the sun. Therefore I believe this planet is no longer considered apart of our Solar System.