Johannes Kepler (December 27; 1571 - November 15; 1630) was a German mathematician; astronomer; and astrologer. A key figure in the 17th century scientific revolution; he is best known for his laws of planetary motion; based on his works Astronomia nova; Harmonices Mundi; and Epitome of Copernican Astronomy. These works also provided one of the foundations for Isaac Newton's theory of universal gravitation.

During his career; Kepler was a mathematics teacher at a seminary school in Graz; Austria; where he became an associate of Prince Hans Ulrich von Eggenberg. Later he became an assistant to astronomer Tycho Brahe; and eventually the imperial mathematician to Emperor Rudolf II and his two successors Matthias and Ferdinand II. He was also a mathematics teacher in Linz; Austria; and an adviser to General Wallenstein. Additionally; he did fundamental work in the field of optics; invented an improved version of the refracting telescope (the Keplerian Telescope); and mentioned the telescopic discoveries of his contemporary Galileo Galilei.