Camille Flammarion (1842-1925) began his career at 16 as a human computer under the great mathematician U. J. J. Le Verrier at the Paris Observatory. He soon tired of the drudgery; he was drawn to more romantic vistas, and at 19 wrote a book on an idea that he was to make his own—the habitability of other worlds. There followed a career as France’s greatest popularizer of astronomy, with …