What is a comet? Where does it come from? What is it made of, and how long does it last? Are comets the building blocks from which the planets were formed? These are just a few of the intriguing questions addressed in this spectacular book by the Pulitzer Prize-winning scientist and author of Cosmos--the greatest science bestseller of all time.Written with his longtime collaborator, Ann Druyan, Carl Sagan's COMET is the definitive work on its subject. Beginning with a breathtaking journey through space astride a comet, Sagan and Druyan probe the myths and portents that comets have given rise to around the world and across the centuries. They trace scientific enterprises that have been devoted to comets, the rivalries and controversies that have been inspired by them, and examine comet activity from 1987 to the present--including the forthcoming appearance of Hale-Bopp, currently anticipated to be fifty times brighter in our skies than Halley's or Kohoutek.