ALPHABETICAL BRAIN VOCABULARY 100 MOST INFLUENTIAL SCIENTISTS #9 JOHANNES KEPLER Life Dates = 1571-1630 A.D. Johannes Kepler was a German mathematician, astronomer, and astrologer. He was a key figure in the 17th century scientific revolution and is best known for his laws of planetary motion, which were 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. Eventually, he became the imperial mathematician to Emperor Rudolf II and his two successors Matthias and Ferdinand II. Kepler was also a mathematics teacher in Linz, Austria, and an adviser to General Wallenstein. Also 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. Kepler lived in an era when there was no clear distinction between astronomy and astrology. However, 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. Kepler called his new astronomy "celestial physics" and described it as "an excursion into Aristotle's Metaphysics" and as "a supplement to Aristotle's On the Heavens". Thus he transformed the ancient tradition of physical cosmology by treating astronomy as part of a universal mathematical physics. SOURCES = The Scientific 100 by John Simmons, Britannica Encyclopedia, and Wikipedia. INSTANTLY GO TO: 100 SCIENTISTS RANKED BY NAME AND CENTURY OF DISCOVERY OR INVENTION (1-10) OR RETURN TO: ALPHABETICAL BRAIN™ VOCABULARY INDEX