Nicolaus Copernicus

Copernicus, Nicolaus (1473–1543), Polish astronomer who put forward the theory that the earth and other planets orbit the sun. Until the time of Copernicus, Ptolemy's theory that the earth was the center of the universe and that heavenly bodies, with the exception of the “fixed” stars, rotated around it, was generally accepted.

Copernicus studied mathematics and astronomy at the University of Krakow, and completed his education in Italy, He returned to Poland to become a canon in Frauenberg cathedral.

Many of the astronomers of Copernicus's day were dissatisfied with Ptolemy's theory, which was becoming more and more complex in order to take account of new discoveries about the universe. Copernicus tried to account for the observed motions of the planets by assuming that the earth and planets orbited the sun. He found that his system was much simpler than Ptolemy's complex picture of the universe. Afraid of a hostile reaction to his ideas, Copernicus began to circulate his theory anonymously until a pupil, Georg Joachim Rheticus, published a popular version of it in 1540. This version was enthusiastically received and Copernicus finally published his book On the Revolutions of the Celestial Spheres.

See also: Astronomy.