Colorized portrait of Johannes Kepler (December 27, 1571 - November 15, 1630), a German mathematician, astronomer and astrologer. A key figure in the 17th century scientific revolution, best known for his works Astronomia nova, Harmonices Mundi, and Epitome Astronomiae Copernicanae. Kepler devised the three fundamental laws of planetary motion: 1) The planets orbit the Sun in elliptical paths, with the Sun at one focus of the ellipse. 2) The closer a planet comes to the Sun, the faster it moves. 3) The ratio of the cube of a planet's mean distance from the Sun to the square of its orbital period is a constant.