Carl Sagan was Professor of Astronomy and Space Sciences and Director of the Laboratory for Planetary Studies at Cornell University. He played a leading role in the Mariner, Viking, and Voyager spacecraft expeditions to the planets, for which he received the NASA medals for Exceptional Scientific Achievement. Dr. Sagan received the Pulitzer Prize and the highest awards of both the National Academy of Sciences and the National Science Foundation, and many other awards, for his contributions to science, literature, education, and the preservation of the environment. His book Cosmos (accompanying his Emmy- and Peabody Award-winning television series of the same name) was the bestselling science book ever published in the English language, and his bestselling novel, Contact, was turned into a major motion picture. Photo by NASA/JPL [Public domain], via Wikimedia Commons.