Question: What profession does Jack Green and Gerard Kuiper have in common?

Related documents: [0]  [DOC] Gerard Peter Kuiper ( ; ] ; 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. [END] 
[1]  [DOC] Jack Green (18 June 1925 – 5 September 2014) was a geologist and geology professor at California State University Long Beach. His active research included general volcanology and economic geology, as well as mineralogy, lunar protolife, lunar volcanism, water on the moon and astrobiology. His passion for volcanology and the moon was primarily in trying to prove that lunar craters were volcanic and not asteroid impacts, and therefore, there would be water on the moon which would support life. He collaborated with Urey, Shoemaker, Kuiper and others during the "Space Age" heyday, and was active in planning several conferences on remote sensing and the moon. [END]  
Answer: professor
professor