Many scholars accepted the theory of the Greek philosopher Aristotle. He said that the earth was round, stationary, and located in the middle of the universe. The moon, sun and five planets circled it. As astronomers learned more about the universe, they found that they had to keep adding epicycles to explain the motion of the planets and their schemes became very complicated. But Nicolaus Copernicus changed that theory.
Nicolaus Copernicus was born on February 19, 1473 in Thorn, Poland. He died May 24th, 1543 after a long, successful life. Copernicus was the son of a prosperous merchant and was raised by a protective uncle after his father's death. His uncle enabled him to enter the University of Krakow, which was famous for its mathematics, philosophy, and astronomy courses. Next he studied liberal arts at Bologna, medicine at Padua, and law at the University of Ferrara. He left Ferrara in 1503 with a doctorate in canon law. He returned to Poland and settled at the cathedral in Frauenberg. As an elected canon of the church, he not only faithfully performed his duties, but practiced medicine, wrote a treatise on monetary reform, and turned his attention toward astronomy, a subject which had interested him for a long time.
Copernicus decided to challenge the theory of Ptolemy, which was that the earth was motionless and the center of the universe. He believed that Ptolemy's theory was too complicated and he decided that the most simplest and logical explanation was that the earth had to spin around its axis once every day and every planet, including the earth, revolved around the sun. Copernicus realized that his theory implied that the universe was larger than what was originally thought.
Copernicus hesitated to publish his theory because he knew it would cause controversy. Many scientists still accepted the medieval paradigm that favored tradition over change. Finally he published his ideas in his book "On the Revolutions of the Heavenly Spheres'.
