What are these graceful visitors to our skies? We now know that they bring both life and death and teach us about our origins. Comet begins with a breathtaking journey through space astride a comet. Pulitzer Prize-winning astronomer Carl Sagan, author of Cosmos and Contact, and writer Ann Druyan explore the origin, nature, and future of comets, and the exotic myths and portents attached to them. The authors show how comets...