Sagan, Carl Edward (1934–1996)

US physicist and astronomer who popularized astronomy through writings and broadcasts. His main research was on planetary atmospheres. He wrote or co-wrote 27 books, which include Broca's Brain: Reflections on the Romance of Science (1979) and Cosmos (1980), based on his television series of that name.

Sagan researched the origin of life on Earth, the probable climatic effects of nuclear war, and the possibility of life on other planets.

Sagan was born in New York and studied at Chicago. He became professor of astronomy and space science at Cornell University 1970, and has provided data for several NASA space-probe missions, especially Mariner 9 to Mars.

In the early 1960s Sagan determined the surface temperature of Venus. He then turned his attention to the early planetary atmosphere of the Earth, and, like US chemist Stanley Miller before him, was able to produce amino acids by irradiating a mixture of methane, ammonia, water, and hydrogen sulphide. In addition, his experiment produced glucose, fructose, nucleic acids, and traces of adenosine triphosphate (ATP, used by living cells to store energy).

Other works by Sagan are Cosmic Connection: An Extraterrestrial Perspective (1973) and the science fiction novel Contact (1985).

He was married three times and had five children. His first wife was the biologist Lynn Margulis.