Carl Edward Sagan (November 9, 1934 - December 20, 1996) was an American astronomer who made science extremely popular through his television series, Cosmos. He pioneered exobiology and promoted the Search for ExtraTerrestrial Intelligence (SETI).

Carl Sagan was born in Brooklyn, New York. His father, Sam Sagan, was a Jewish garment worker and his mother, Rachel Molly Gruber, was a housewife. Sagan attended the University of Chicago, where he received a bachelor`s degree (1955) and a master`s degree (1956) in physics, before earning his doctorate (1960) in astronomy and astrophysics. He taught at Harvard University until 1968, when he moved to Cornel University.

Sagan was among the first to hypothesize that Titan and Jupiter`s moon Europa may possess oceans (a subsurface ocean in the case of Europa) or lakes - thus making the hypothesized water ocean on Europa potentially habitable for life. Europa`s subsurface ocean was later indirectly confirmed by the spacecraft Galileo. He furthered insights regarding the atmosphere of Venus, seasonal changes on Mars, and Saturn`s moon Titan. Sagan established that the atmosphere of Venus is extremely hot and dense. He also perceived global warming as a growing, man-made danger and likened it to the natural development of Venus into a hot life-hostile planet through greenhouse gases. He suggested that the seasonal changes on Mars were due to windblown dust, not to vegetation changes, as others had proposed.

Sagan was also a proponent of the search for extraterrestrial life. He urged the scientific community to listen with large radio telescopes for signals from intelligent extraterrestrial lifeforms. He advocated sending probes to other planets. Sagan was Editor in Chief of Icarus (a professional journal concerning planetary research) for 12 years. He co-founded the Planetary Society and was a member of the SETI Institute Board of Trustees. He was well known as a co-author of the scientific paper that predicted nuclear winter would follow nuclear war. Sagan famously predicted that smoky oil fires in Kuwait (set by Saddam Hussein`s army) would cause an ecological disaster of black clouds. Retired atmospheric physicist Fred Singer dismissed Sagan`s prediction as nonsense, predicting that the smoke would dissipate in a matter of days.

After a long and difficult fight with myelodysplasia, Sagan died at the age of 62, on December 20, 1996, at the Fred Hutchinson Cancer Research Center in Seattle, Washington.

The landing site of the unmanned Mars Pathfinder spacecraft was renamed the Carl Sagan Memorial Station in honor of Dr. Sagan on July 5, 1997. Asteroid 2709 Sagan is also named in his honor.