and astronomer who has popularized astronomy through writings and broadcasts.
His main research has been on planetary atmospheres. His books include
Broca's Brain: Reflections on the Romance of Science 1979 and Cosmos
1980, based on his television series of that name.
Sagan has also done research into the origin of life on Earth, the probable
climatic effects of nuclear war, and the possibility of life on other
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
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.