Eccentric Planet portrays the relationship between the young Renaissance mathematician Rheticus, and Nicolas Copernicus, the reclusive and cautious astronomer. In 1542 Rheticus described himself as "a rather daring young man." Some might call him reckless. Arthur Koestler, in The Sleepwalkers, presents Rheticus as: "...one of the knights errant of the Renaissance whose enthusiasm fanned borrowed sparks into flame...an enfant terrible, an inspired fool, a condottiere of science, an adoring disciple and, fortunately, either homo- or bi-sexual after the fashion of the time. I say "fortunately" because the so afflicted have always proved to be the most devoted teachers and disciples, from Socrates to this day, and History owes them a debt." A 25-year-old professor at Wittenberg, Rheticus ventured in 1539 to the distant Baltic coast in search of the secretive Copernicus. Brilliant, exuberant, Lutheran and audacious, he presented multiple challenges to the elderly Catholic canon Copernicus. They argued and struggled, and--despite a final betrayal--brought forth a book that changed our understanding of the universe.