Spectacular and mysterious objects that come and go in the night sky, comets have dwelt in our popular culture for untold ages. As remnants from the formation of the Solar System, they are objects of key scientific research and space missions. As one of nature's most potent and dramatic dangers, they pose a threat to our safety - and yet they were the origin of our oceans and perhaps even life itself. This beautifully illustrated book tells the story of the biggest and most awe-inspiring of all comets: those that have earned the title 'Great'. It focuses on Great Comets Hyakutake in 1996 and Hale-Bopp in 1997, which gripped attention world-wide because, for many, they were the first comets ever seen. For everyone interested in astronomy, this exciting book reveals the secrets of the Great Comets and provides essential tools for keeping up-to-date with comet discoveries in the future.