It was Copernicus who, in 1543 in his De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres) placed the Sun as the center of the Solar System with the planets revolving around it. Then in the early seventeenth century Johannes Kepler published his three laws governing the motion of the planets around the Sun. These were derived empirically from a wealth of astronomical data compiled by the Danish astronomer Tycho Brahe.