Clyde William Tombaugh was an American astronomer. He discovered Pluto in 1930, the first object to be discovered in what would later be identified as the Kuiper belt. At the time of discovery, Pluto was considered a planet but was later controversially reclassified as a dwarf planet in 2006. Tombaugh also discovered many asteroids. He also called for the serious scientific research of unidentified flying objects, or UFOs.