Kepler, Johannes (yōhä`nəs kĕp`lər), 1571–1630, German astronomer. From his student days at the Univ. of Tübingen, he was influenced by the Copernican teachings. From 1593 to 1598 he was professor of mathematics at Graz and while there wrote his Mysterium cosmographicum (1596). This work opened the way to friendly intercourse with Galileo and Tycho Brahe, and in 1600 Kepler became Tycho's assistant in his observatory near Prague. On Tycho's death (1601) Kepler succeeded him as court mathematician to Holy Roman Emperor Rudolf II. In 1609 he published the results of Tycho's calculations of the orbit of Mars. In this celebrated work were stated the first two of what became known as Kepler's laws Kepler's laws, three mathematical statements formulated by the German astronomer Johannes Kepler that accurately describe the revolutions of the planets around the sun. Kepler's laws opened the way for the development of celestial mechanics, i.e.
..... Click the link for more information. . In 1612, becoming mathematician to the states of Upper Austria, he moved to Linz. He wrote an epitome of the astronomy of Copernicus in 1618, and in 1619 De cometis and Harmonice mundi (in which was announced the third of Kepler's laws). In 1626, Kepler moved to Ulm. After his death his manuscript writings, bought by Catherine II of Russia, were placed in the observatory of Pulkovo.

Bibliography

See biographies by M. Caspar (tr. 1959, repr. 1962) and A. Armitage (1966); A. Beer, ed., Kepler: Four Hundred Years (1974).

Kepler, Johannes

(born Dec. 27, 1571, Weil der Stadt, Württemberg—died Nov. 15, 1630, Regensburg) German astronomer. Born into a poor family, he received a scholarship to the University of Tübingen. He received an M.A. in 1594, after which he became a mathematics teacher in Austria. He developed a mystical theory that the cosmos was constructed of the five regular polyhedrons, enclosed in a sphere, with a planet between each pair. He sent his paper on the subject to Tycho Brahe, who invited Kepler to join his research staff. In attempting to understand atmospheric refraction of light, he became the first to explain accurately how light behaves within the eye, how eyeglasses improve vision, and what happens to light in a telescope. In 1609 he published his finding that the orbit of Mars was an ellipse and not the perfect circle hitherto presumed to be the orbit of every celestial body. This fact became the basis of the first of Kepler's three laws of planetary motion. He also determined that planets move faster as they near the Sun (second law), and in 1619 he showed that a simple mathematical formula related the planets' orbital periods to their distance from the Sun (third law). In 1620 he defended his mother from charges of witchcraft, thereby preserving his own reputation as well.