Carl Sagan, the astronomer and Pulitzer Prize-winning author whose books and television shows fired the imaginations of millions of people, was born 9 November 1934. Arguably the greatest science popularizer of the 20th century, Sagan gained fame for hosting Cosmos, the Emmy Award-winning PBS series that ran in the late 1970s and is estimated to have reached 500 million people worldwide.
Sagan's research at Cornell University had focused on the origin of life on Earth. He also was an active player on large scientific teams analyzing data from missions to Mars, Venus, and other planets. Perhaps his best known work to scientists outside his field, however, was his passionate defense of the controversial nuclear winter theory, which holds that a nuclear war would chill Earth's climate for years.
But while Sagan charmed most of the world, he rubbed some prominent scientists the wrong way. In 1992, his astronomy colleagues proposed him for membership in the prestigious National Academy of Sciences. Sagan appeared to make the final cut, but an eleventh-hour debate among academy mandarins over whether his research accomplishments were up to snuff ended his candidacy. Two years later, however, the academy offered an olive branch when it awarded Sagan its Public Welfare Medal, presented annually "to honor the extraordinary use of science for the public good." Sagan died in 1996 at age 62.