Gerard Peter Kuiper (English pronunciation: /ˈkaɪpər/; Dutch pronunciation:[ˈkœypər]; born Gerrit Pieter Kuiper; December 7, 1905 – December 23, 1973) was a Dutch–American astronomer, planetary scientist, selenographer, author and professor. He is the eponymous namesake of the Kuiper belt. Kuiper is considered by many to be the father of modern planetary science. As professor at the University of Chicago, he was dissertation advisor to Carl Sagan. In 1958, the two worked on the classified military Project A119, the secret Air Force plan to detonate a nuclear warhead on the Moon.