Nicolaus Copernicus was born in Torun, Poland, the son of a German mother and Slavic father. Like Tycho Brahe, he was raised by his uncle-the bishop of Ermeland. Copernicus was not trained as a scientist, nor was his job an officially scientific one. He studied mathematics, optics, and medicine at the University of Krakow and canon law at the University of Bologna in Italy. Copernicus received a degree from the University of Ferrara in 1506 and returned to Poland when his uncle presented him with the canonry of the cathedral at Frauenberg, East Prussia (now part of Poland). As canon of Frauenberg, Copernicus developed a routine in which he divided his "working" day into thirds. One-third was devoted to religious duties, another third was for providing charity to the sick in need of medical attention, and the final third was devoted to his hobby---the study of astronomy and philosophical meditation. Copernicus's life was devoted to understanding planetary motion. He became famous for proposing that the sun rather than earth was the center of the solar system. A preliminary version of this theory was circulated privately in 1514. However, the first publication of this radical idea, De Revolutionibus Orbium Coelestium (On the Revolutions of the Heavenly Spheres), was not published until 1543, the year of his death. Copernicus's theory finally was accepted nearly 100 years later, when measurements and analyses by Johannes Kepler, Brahe, Galileo, Sir Isaac Newton, and others permitted detailed, quantitative comparisons between predictions of the Copernican model and observation of planetary positions. he acceptance of a heliocentric solar system proposed by Copernicus represents the most fundamental change in our conception of the solar system. Because of Copernicus's leading role in this changing perspective, astronomers refer to this period as the Copernican Revolution.