In the spring of 1539, Georg Rheticus, a 25-year-old mathematics prodigy met the not-yet-famous amateur astronomer Nicolaus Copernicus. There were rumors for years about his revolutionary theory that the sun, not the earth, was at the center of the universe, and about a manuscript he had almost completed on the subject. By autumn of 1541, the astronomer had completed his manuscript, ¿De revolutionibus,¿ and Rheticus persuaded his mentor to let him take it to Germany for publication. This enabled Copernicus¿ seminal work to usher in a new understanding of the physical universe. This is the first popular account of the life of Rheticus -- Copernican muse, founder of modern trigonometry, and champion of new science. ¿The definitive story.¿ Illustrations.