This biography of Johann Kepler is unique in that it follows the development of Kepler's theories in logical sequence and in language young readers will readily grasp. During the course of his studies at the University of Tubingen, Kepler became fascinated by astronomy. With the encouragement of Professor Maestlin and the use of Tycho Brahe's measuring instruments, Kepler began to experiment with known theories. He drew from the work of Copernicus and then discarded certain concepts. One of his major discoveries was that ellipses, not circles, trace the route of the planets and that the sun is the focal point of the universe. The biography does not isolate Kepler's scientific achievements. They are discussed in the full context of his life and times. The struggle between Catholics and Protestants, Kepler's refusal to convert to Catholicism, the brilliant defense of his own mother against charges of witchcraft, the peasant uprising in Germany all add the necessary dimensions for a rounded and lively portrait.