Carl Edward Sagan ( \ / ˈseɪɡən \ / ; November 9 , 1934 - December 20 , 1996 ) was an American astronomer , astrophysicist , cosmologist , author , science popularizer and science communicator in astronomy and natural sciences .
Carl Edward Sagan ( November 9 , 1934 - December 20 , 1996 ) was an American astronomer .