Photograph of Carl Sagan Courtesy of Robert Reichert and Cornell University.

Carl Sagan is an American astronomer who was born in 1934. He is famous for his research on the start of life and his belief that life exists on other planets in the universe.

Sagan has played a leading role in the space program, and in the recent spacecraft voyages to Mars and other planets in our solar system.

Sagan passed away on December 20, 1996.