By Megan Harlan
Updated November 19, 1999 at 05:00 AM EST

Famous for championing the existence of extraterrestrial life, Carl Sagan, who died in 1996 at 62, was the world’s first celebrated ”media scientist”: His PBS astronomy series, Cosmos, drew half a billion viewers, and several of his books, including Contact, became best-sellers. This brainily vibrant bio stresses how Sagan sacrificed academic credibility for his beliefs: Harvard, for example, denied him tenure for allegedly being too ”flamboyant” (it didn’t help matters that he was a cofounder of SETI, Search for Extraterrestrial Intelligence). But after settling at Cornell, Sagan not only consulted on Pioneer, Viking, and Voyager missions but eloquently explained them to the world. Science journalist Poundstone captures both the black holes in Sagan’s personal life (his failures as a husband and father) and the prodigious dimensions of Sagan’s mind, energy, and imagination. B+