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...