17/01/1997 American astronomer Clyde Tombaugh dies
Reflections on Clyde Tombaugh
NMSU gives closer look into Clyde Tombaugh's work
Tombaugh is known because of his discovery of the dwarf planet Pluto in 1930. Pluto was considered a planet for until reclassification in 2006. It was the first object from the Kuiper belt ever observed. The Kuiper belt is a disc of small objects extending from the orbit of Neptune (30 astronomical units, AU) to the distance around 50 AU.