Johannes Kepler was an obsessive, devout teacher of astronomy, and Tycho Brahe was a cruel, extravagant aristocrat who believed the sun orbited the Earth. Kepler's analytical abilities were said to be second to none, while Brahe was one of the best observational astronomers of all time. Their meeting in Prague in 1600 led to an extraordinary, if uneasy, alliance which eventually resulted in a huge leap forward in the understanding of astronomy. Together they produced the first three laws of planetary motion. This book tells the story of a major watershed in the history of human thought.