“You probably don't need more weapons than what's required to destroy every city on earth. There's only 2,300 cities. So, the United States, by that criteria, only needs 2,300 nuclear weapons - well, we've got more than 25,000!”

American astronomer, planetary scientist and science communicator

Carl Edward Sagan was an American astronomer, planetary scientist and science communicator. He worked at Harvard as an assistant professor before moving to Cornell University, where he became the David Duncan Professor of Astronomy and Space Sciences and directed the Laboratory for Planetary Studies. Sagan took an active role in the Mariner, Viking and Voyager programs. He also wrote more than 600 scientific papers and articles, along with several popular science books, beginning with The Cosmic Connection. His The Dragons of Eden won the Pulitzer Prize for General Nonfiction.