. The Nuclear WinterCarl SaganCarl Sagan, a modern-day Renaissance man of science, was horn in 1934 in New York. After graduating with both a B.A. and a B.S. degree from the University of Chicago, Sagan completed his M.S. in physics and earned a Ph.D. in astronomy and astro-physics in 1960. Sagan was nominated to join the Smithsonian Astrophysical Observatory in 1962. At the same time, he also worked with the Nobel-prize winner Joshna Lederberg, investigating the origins of life on earth, and taught genetics at Stanford. Sagan then taught astronomy at Harvard until 1968, when he became profossor of astronomy and space sciences at Cornell University. He was then appointed director of the laboratoy for Planetary Studies. Sagan was awarded the NASA medal for exceptional scientific achievement in 1972, after his hypotheses about Mars were validated by data obtained from the 1971 Mars Mariner expedition. Beginning in 1968, Sagan was editor of Icarus, the international journal of astronomy, and wrote many distinguished books.
