Johannes Kepler

Johannes Kepler (1571–1630), born at Weil der Stadt, was a German astronomer and mathematician. He taught mathematics before moving to Prague in 1600 as Tycho Brahe's assistant; after Brahe's death in 1601 he inherited his observations and became imperial mathematician under Rudolf II.

In Astronomia nova (1609) he showed that Mars moves in an ellipse and formulated his first two laws of planetary motion, the third following in Harmonice Mundi (1619). Later based in Linz and then Sagan, he died at Regensburg in November 1630; his laws underpinned Newton's theory of universal gravitation.