Kepler, Johannes

BORN 27 Dec 1571, Weil, Baden-Württemberg (near Stuttgart) - DIED 15 Nov 1630, Regensburg, Bayern
GRAVE LOCATION Regensburg, Bayern: St. Peter Friedhof (grave disappeared)

Johannes Kepler was born in Weil, now part of the Stuttgart region. His grandfather had been mayor of the city, but his father worked as a mercenary and left the family when Johannes was five years old. His mother Katharina Guldenmann was the daughter of an innkeeper. She was a herbalist. He saw the Great Comet of 1577 and was interested in astronomy from an early age. In 1589 he entered the University of Tübingen, where Vitus Müller as his philosophy teacher and Jacob Heerbrand taught him theology. Michael Maestlin was his mathematics teacher.

Instead of entering the clergy, in 1594 he was engeged as teacher of mathematics and astronomy at the Protestant School in Graz. In 1596 he published "Mysterium Cosmographicum" ("The Cosmographic Mystery") in defense of the concept of a heliocentric universe by Copernicus. On 27 April 1597 he marrried the widow Barbara Müller although the family initally objected because of his poverty. Barbara Müller already had a daughter, Regina Lorenz. Together they had five children, three of whom survived.

He started corresponding with Tycho Brahe and he met him on 4 February 1600 at Benátky nad Jizerou near Prague. On 2 August 1602 he was banished from Graz after he refused to convert to Catholicism. He took his family to Prague, where Brahe engaged him for a new project, the Rudolphine Tables. After Brahe died on 24 October 1601 Kepler succeeded him as imperial mathematician. Until he 1612 he also worked for Rudolph II as his astrological adviser. In 1605 he discovered that the movements of the planet Mars fitted an ellipse and he concluded that all planets moved in ellipses with the sun at one focus. This would be known as his first law of planetary motion. In 1610 he was in contact with Galileo Galileï. By 1611 Rudolph II's health was failing and Kepler's prospects in Prague worsened. In 1611 Barbara contracted a fever and suffered from seizures. His son Friedrich died aged six.

The University of Padua was interested in engaging him, on advice of the retiring Galileï. But Kepler preferred to return to German ground and accepted a position as teacher and district mathematician in Linz. Before he colud leave Prague Barbara died. He stayed there until Rudoplh II died in 1612. The new emperor Matthias confirmed his position as imperial mathematician but allowed him to move to Linz. On 30 October he married Susanna Reuttinger. She was 24 years old and he chose her from 11 women. It was a good marriage and by Susanna he had three more surviving children.

From 1617 to 1621 he published "Epitome astronomiae Copernicanae" ("Epitome of Copernican Astronomy") in which he formulated his three laws for planetary motion. In August 1620 his mother Katharina was imprisoned after she had been accused of witchcraft in 1617 after a dispute with a woman named Ursula Reingold in 1615. Kepler contributed to her defense and she was released in October 1621.

In 1623 he completed the Rudolphine Tables, but publishing requirements of the emperor and negotiations with Tycho Brahe's heir prevented publication until 1627. In 1626 Linz was under siege and Kepler moved to Ulm. In 1628 he became official advisor to general Wallenstein. He visited Praque and Linz again and temporarily lived in Sagan in Western Poland. During a visit to Regensburg he fell ill and he died on 15 November 1630.

He was buried in Regensburg, outside the city walls because he was protestant. The cemetery was destroyed in 1632 or 1633 euding the Thirty Years War. In August 1636 Susanne died in Regensburg as well. In 1808 a small temple was placed in the area where he had presumably been buried.

Related persons
• was written about by Schuder, Rosemarie

0/10/1601Kepler is engaged as imperial mathematician by emperor Rudolph II. He succeeded Tycho Brahe, who had died. Before that Brahe had recommended Kepler as his successor to the emperor. 


Kepler memorial at the Stadtpark, Graz.
Picture by Androom (15 Aug 2009)


Plaque for Johannes Kepler at the Rathaus in Ulm, Baden-Württemberg.
Picture by Androom (23 Aug 2016)


Monument for Johannes Kepler in Regensburg.
Picture by Androom (31 Aug 2016)


Monument for Johannes Kepler in Regensburg.
Picture by Androom (31 Aug 2016)


• Vocelka, Karl, Rudolf II. und Seine Zeit, Böhlau, Wien, 1985
Johannes Kepler - Wikipedia

Keppel, Alice

Published: 19 Apr 2020
Last update: 13 Aug 2023