context: Carl Edward Sagan (November 9, 1934 - December 20, 1996) was an American astronomer, astrophysicist, astrobiologist, and generalist in science. For most of his career he worked at Cornell University, where he served as professor from 1971 until his death. Sagan is known for his numerous studies and theories in the field of exobiology and his great influence on the launch of the SETI program for extraterrestrial intelligence. In his work, he repeatedly sought to promote scientific research methods. [1]
question: When did Carl Sagan die?
answers.text: December 20, 1996