John Kepler was born in 1571 in Weil der Stadt, Wurttemburg, in the Holy Roman Empire, the son of a poor mercenary soldier. He began his education in Württemburg through a scholarship program designed to train Lutheran teachers and pastors. In 1589 Kepler entered the theological seminary of the University of Tübingen. It was here that he first learned Copernican astronomy from Michael Maestlin. The University of Tübingen awarded Kepler his master's degree in 1591. In 1594 Kepler interrupted his theological studies and accepted a position as a mathematics teacher at the Lutheran school in Graz, however, he was later dismissed from the position in 1600 due to religious persecution and a standing order for all Lutherans to leave the district. Earlier that year, Kepler temporarily worked with Emperor Rudolf II's imperial mathematician, Tycho Brahe. . Kepler later traveled to Prague to join Brahe and work as his assistant until Brahe's death in 1601, whereupon Kepler was appointed successor as Imperial Mathematician. The nomination was the most prestigious honor in all of Europe for mathematics of its time. While working as Brahe's assistant, Kepler was given the task of studying and attempting to understand the orbit of the planet Mars. The orbit of Mars was particularly difficult because Copernicus had correctly placed the Sun at the center of the Solar System, but had erred in his assumption of circular planetary orbits. After numerous experiments and mathematical calculations, he finally realized that the orbits of the planets were in fact not circular as Aristotle had previously insisted and Copernicus believed correct, but were actually more elliptical in shape. The fact that Mars has the most elliptical of all the orbits on which Kepler had data led Kepler eventually to formulate the correct theory for the Solar System. After Brahe's death Kepler managed to obtain all of Brahe's data and observations. Using Brahe's voluminous and precise data, Kepler was able to use his understanding of the elliptical orbits of the planets to formulate his Three Laws of Planetary Motion, his most important achievement and the only one for which history particularly remembers him . Planetary motion is "The orbits of the planets are ellipses, with the Sun at one of the foci of the ellipse." The Sun is not at the center of the ellipse but is in a focus. The planet then follows the ellipse in its orbit, meaning that the planet-Sun distance is constantly changing as the planet goes around its orbit.