ABSTRACT
U.S. astronomer and populariser of science. He completed his education at the University of Chicago, obtaining degrees in physics before obtaining his Ph.D. in astronomy and astrophysics in 1960. He taught at Harvard before moving to Cornell University in 1968, where he was appointed professor of astronomy and space science in 1971; he was also the director of a Laboratory for Planetary Studies and was editor-in-chief of Icarus, the principal journal of planetary studies, for twelve years. The first of his three marriages, in 1957, was to Lynn Margulis, the biologist who collaborated with James *Lovelock on the development of the Gaia hypothesis, and he retained a strong interest in environmental issues, helping to popularise the dangers of the *greenhouse effect and the notion that the use of *atom bombs in warfare would precipitate a "nuclear winter".
