Pluto is a dwarf planet in the Kuiper belt, a ring of bodies beyond Neptune. Discovered by American astronomer Clyde Tombaugh in 1930, it was originally considered the ninth planet from the Sun. Its status as a planet was questioned after other similar size objects were discovered in the Kuiper belt, and in 2006 the International Astronomical Union (IAU) officially reclassified it as a dwarf planet.