Inspirational Quotes by Johannes Kepler (German Astronomer)

Johannes Kepler (1571–1630) was a German mathematician and astronomer. One of the principal founders of modern astronomy, he supported Copernicus’s heliocentric theory and discovered the three basic laws that govern the orbital motion of planets. In so doing, Kepler posed questions of planetary motion that it took Isaac Newton to answer.

Born in Weil der Stadt, Württemberg, Kepler was educated at the University of Tübingen where he obtained a master’s degree in theology in 1591. He became a professor of mathematics in Graz in 1594, where he learned of the work of Copernicus and supported the heliocentric theory. He also published almanacs to forecast the weather and to predict favorable days per the rules of astrology. He recorded in his first major publication, the Mysterium Cosmographium (1596,) that the distances from the Sun of the six planets including the Earth could be related to the five regular solids of geometry, of which the cube is the simplest.

Kepler settled in Prague in 1599, becoming Dutch astronomer Tycho Brahe’s assistant and later court mathematician to Emperor Rudolf II. It was in this position that he discovered the laws governing planetary motion, and foreshadowed the general application of the scientific method to astronomy.

After a study of the planet Mars, Kepler determined that its movement could not be explained in terms of the customary cycles and epicycles. This proclamation broke with the tradition of more than 2,000 years—Kepler demonstrated that the planets do not move uniformly in circles, but in ellipses with the sun at one focus and with the radius vector of each planet describing equal areas of the ellipse in equal times (Kepler’s first and second laws.) In Harmonices Mundi (1620,) he expounded the third law of planetary dynamics, relating the distances of the planets from the sun to their orbital periods.

In 1627, Kepler published the Tabulae Rudolphinae, which contained the ephemerides of the planets according to the new laws, and an expansive catalog of 1,005 stars based on Tycho’s observations. Among Kepler’s other achievements are a description of optic vision, a study of the behavior of light in the newly invented telescope, and discovery of the geometry of semiregular polyhedrons.

A popular biography is Max Caspar’s Kepler (1959.)

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