Johannes Kepler

Birth Data

Biography

German author, mathematician, scientist, astronomer, court astrologer and teacher. Known as "the father of modern astronomy," he discovered the three laws of planetary motion which paved the way a half century later for Newton's laws of universal gravitation. The leading astronomical theorist for over 400 years, he was regarded as having "one foot in medieval mysticism and one foot in the scientific method."

The son of peasants, Kepler's prodigious ability placed him as a student in the University of Tubingen, where he was strongly influenced by Copernican teachings. Following graduation, he was professor of mathematics at the University at Graz where he wrote "Mysterium Cosmographicum" in 1596, a treatise which initiated a correspondence with Danish Astronomer Tycho Brahe, who subsequently employed Kepler as his assistant at his observatory near Prague, 1600. It was there Kepler discovered his laws of planetary motion governing elliptical orbits, which were motivated by his desire to prove the Pythagorean Music of the Spheres.

Following Brahe's untimely death the following year, Kepler succeeded him as Court Mathematician to Holy Roman Emperor Rudolf II, King of Bohemia and Hungary. After publishing Brahe's calculations on the orbit of Mars in 1609, he became Mathematician to the States of Upper Austria and moved to Linz in 1612, where he wrote "De Cometis and Harmonic Mundi."

Kepler's mathematical genius allowed him to see mathematical formulas of planetary orbit hidden in the rough pre-telescope observational data of Tycho Brahe. Thus he became the first scientist to derive precise, universal laws from empirical data. He also invented log tables, an essential tool for calculating planetary positions.

As a professor and an astronomer Kepler held grave doubts about astrology, but practice and experience persuaded him to reconsider the celestial science. "A most unfailing experience (as far as can be expected in nature) of the excitement of sublunary (that is, human) natures by the conjunctions and aspects of the planets has instructed and compelled my unwilling belief."

He repeatedly penned letters to friends to "separate the gems from the slag," and in later years, accepted the position of Court Astrologer to Albrecht Wallenstein, Bohemian general and imperial commander of armies in the Thirty Years War. Despite his rank as a Court Astrologer, Kepler lived on the edge of poverty and died in this condition on 11/15/1630 in Regensburg, Germany.

In the early 1800's, Catherine II of Russia purchased his manuscripts and placed in the observatory at Pulkovo near St. Petersburg, where they allegedly remained. While a member of academia was casually rummaging through an obscure archive at the University of California at Santa Cruz in March 1999, he found a letter "written in the hand of Kepler, from the collection of Kepler manuscripts in Pulkova" illustrating and delineating a horoscope, and was later verified to be authentic.

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