How astronomy's star was born

On September 28 1980, Carl Sagan's star blazed across the television firmament, as the first of 13 parts of Cosmos was aired in the United States. The series, shown on advertisement-free "public television", made Sagan the most familiar scientific face in the US and eventually in the world. The series, in its grandeur and simultaneous excess, shows many of the aspects of Sagan that made him so controversial in the scientific community at the same time that he became so popular with the general public.

Keay Davidson, a science writer, has surveyed Sagan's life and provided a fascinating view of this multifaceted individual. He has interviewed many of those who knew or worked with Sagan, and he sets his successes and his failures in context. The book provides a revealing profile of an individual who had a lasting effect on the way space science is carried out and funded.

My students today, born roughly when Cosmos went on the air, knew of Sagan but had not seen the series. When I pulled a videotape at random off the shelf and showed it to them, we agreed that many pros and cons became apparent even after only a few minutes. One of Davidson's chapters deals with the production and the still-debated question of who deserves credit (blame?) for the spaceship-like platform from which Sagan made on-screen pronouncements. We learn, too, about the role of Sagan's then-new wife, Ann Druyan, and the conflicts between the producer and the Sagan/Druyan team. Davidson discusses both Sagan's scientific carefulness and his personal imperiousness, and whether they were necessarily linked.

In the book, we learn much about Sagan's relations with his three wives, two of whom cooperated with the biographer. Lynn Margulis, now well known as a Boston University biological researcher; Linda Salzman, the artist whose work on the Pioneer spacecraft's plaques has travelled far beyond Jupiter; and Druyan, for whom Sagan left Salzman in 1977, are used in the book to show the evolution of Sagan's personal life. The most vivid character is Sagan's mother, Rachel, an eccentric and unstable person for whom Carl seemed perfect. The security and belief in his impressiveness that she imparted to young Carl moulded his approach to other people, to the world and to the universe.

Perhaps the major theme of Sagan's life, and of Davidson's descriptions, is his involvement in the search for extraterrestrial intelligence. Davidson describes how Sagan came to this interest at the age of eight, and how few people in history have been able to advance their childhood beliefs to such an extent. In Sagan's case, he had the ability to influence the goals of the spacecraft that Nasa was sending to Mars and other planets. The question discussed in the book is whether Sagan went too far in persisting in the search in places where life was shown to be unlikely. Will public interest in space exploration survive the probable conclusion that no life exists on Mars? Though Nasa's programme includes the further investigation of the conditions on planets discovered in the past few years orbiting stars other than our sun and on the origins of other types of objects, should interest be more equally fostered among a wider range of fascinating astronomical topics? Surely Sagan's influence persists in the current path.

I was in a group of undergraduate and graduate students at Harvard University's astronomy department in the years that Sagan was an assistant professor. (I am quoted a couple of times in Davidson's book, and the sense of what I said is fairly conveyed.) I knew not only Carl but also his graduate student Jim Pollack, who was among my closest friends. Davidson describes the Pollack/Sagan collaboration as fundamental and discusses how questions remain as to whether Pollack supplied most of the detailed science in papers of which they were co-authors. Davidson's discussions of Sagan's actual scientific contributions place this and other scientific work in context. Sagan was an ideas man, less interested in carrying out the detailed analyses than in having intriguing thoughts. If he brought insights by thinking perpendicularly to the way others thought, I see little problem in honouring the contributions that he made or influenced. But one can see in Davidson's book how Sagan's problems with many distinguished scientists arose, how Sagan gained the reputation among some of them for contributing little of scientific value, and how his antagonists prevented him from being elected to the National Academy of Sciences.

In his later years, Sagan was very much America's scientific intellectual, writing a column for the low-brow newspaper weekly insert Parade , among other things. His books sold widely, but his mixing of science with speculation and his not necessarily including the latest information or theories in biological and other non-astronomical fields did not help Sagan's reputation with scientists. Still, Pulitzer prizes are not to be sneered at, and Sagan's general respectability as a public intellectual was somewhat at odds with his reputation in astronomy.

Yet, when a gift was made to the American Astronomical Society for a prize in education, the first question to be asked was "Sagan or not Sagan". And the prize did go to Sagan, with the idea in mind that doing so elevated the status of the prize. Further, Sagan was invited to give major addresses before the division of planetary sciences of the American Astronomical Society and before the International Astronomical Union. So, National Academy of Sciences aside, he was well honoured within his field.

Sagan died too young, in 1996, at the age of 62, from a rare blood disease. We in the astronomical community sometimes still look to him, wishing to have him champion our causes when a public voice is needed to defend science. There is no scientist now with the public influence that Sagan had. It is interesting and illustrative for readers of all backgrounds to learn from Davidson's biography how Sagan evolved and how his influence formed and grew.

Jay M. Pasachoff is professor of astronomy, Williams College, Massachusetts, United States