Carl Edward Sagan (9 November, 1934–20 December, 1996) was an American No-Maj astronomer, astrophysicist, cosmologist, author, science popularizer, and science communicator in the space and natural sciences. During his lifetime, he published more than six-hundred scientific papers and popular articles and was author, co-author, or editor of more than twenty books. Carl Sagan wrote the introduction of A Brief History of Time, by Stephen Hawking