Pluto

Pluto (minor-planet designation 134340 Pluto) is the largest object in the Kuiper belt,[i][j] and the tenth-most-massive body observed directly orbiting the Sun. It is the second-most-massive known dwarf planet, after Eris. Like other Kuiper-belt objects, Pluto is composed primarily of rock and ice and is relatively small, approximately one-sixth the mass of the Moon and one-third its volume. It has an eccentric and highly inclined orbit that takes it from 30 to 49 AU (4.4–7.4 billion km) from the Sun. This causes Pluto to periodically come closer to the Sun than Neptune, but an orbital resonance with Neptune prevents the bodies from colliding. In 2014 it was 32.6 AU from the Sun.