Equal parts scientist and public personality, Carl Sagan was one of the most well-known figures of the 20th century. As an adviser to NASA, he helped plan the first moon landing. As an activist, he warned of the dangers of nuclear war. And through his writings and television show, Sagan nurtured the scientific curiosity of audiences around the world, encouraging even the non-scientifically inclined to understand the possibilities that lay in the cosmos and beyond. The remarkable life of the multi-talented Sagan is chronicled within these pages, which survey his personal and professional challenges and his greatest successes.