# Johannes Kepler

Johannes Kepler (/ˈkɛplər/;[2] German: ();[3][4] 27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music.[5] He is a key figure in the 17th-century Scientific Revolution, best known for his laws of planetary motion, and his books Astronomia nova, Harmonice Mundi, and Epitome Astronomiae Copernicanae. These works also provided one of the foundations for Newton's theory of universal gravitation.[6]

Johannes Kepler
Portrait of Kepler by an unknown artist in 1620.
Born27 December 1571
Died15 November 1630 (aged 58)
EducationTübinger Stift, University of Tübingen (M.A., 1591)[1]
Known forKepler's laws of planetary motion
Kepler conjecture
Rudolphine Tables
Scientific career
FieldsAstronomy, astrology, mathematics, natural philosophy
InfluencesNicolaus Copernicus
Tycho Brahe
Pythagoras
InfluencedSir Isaac Newton
Benoit Mandelbrot
Thomas Browne
Signature

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

Kepler lived in an era when there was no clear distinction between astronomy and astrology, but there was a strong division between astronomy (a branch of mathematics within the liberal arts) and physics (a branch of natural philosophy). Kepler also incorporated religious arguments and reasoning into his work, motivated by the religious conviction and belief that God had created the world according to an intelligible plan that is accessible through the natural light of reason.[7] Kepler described his new astronomy as "celestial physics",[8] as "an excursion into Aristotle's Metaphysics",[9] and as "a supplement to Aristotle's On the Heavens",[10] transforming the ancient tradition of physical cosmology by treating astronomy as part of a universal mathematical physics.[11]