Johannes Kepler facts

Johannes Kepler
Portrait of Kepler by an unknown artist, 1610
Born (1571-12-27)December 27, 1571
Free Imperial City of Weil der Stadt, Holy Roman Empire
Died November 15, 1630(1630-11-15) (aged 58)
Regensburg, Electorate of Bavaria, Holy Roman Empire
Residence Württemberg; Styria; Bohemia; Upper Austria
Nationality German
Fields Astronomy, astrology, mathematics and natural philosophy
Alma mater Tübinger Stift, University of Tübingen
Doctoral advisor Michael Maestlin
Known for Kepler's laws of planetary motion
Kepler conjecture
Rudolphine Tables
Influences Nicolaus Copernicus
Tycho Brahe
Influenced Sir Isaac Newton

Johannes Kepler (December 27, 1571 – November 15, 1630) was a German mathematician, astronomer, and astrologer.

Kepler is a key figure in the 17th-century scientific revolution. He is best known for his laws of planetary motion, 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.

Johannes Kepler Observatory Linz
Johannes Kepler Observatory Linz

Kepler was a mathematics teacher at a seminary school in Graz, where he became an associate of Prince Hans Ulrich von Eggenberg. Later he became an assistant to the astronomer Tycho Brahe in Prague, and eventually the imperial mathematician to Emperor Rudolf II and his two successors.

He also taught mathematics in Linz, and was an adviser to General Wallenstein. Additionally, he did fundamental work in the field of optics, invented an improved version of the refracting telescope (the Keplerian telescope), and was mentioned in the telescopic discoveries of his contemporary Galileo Galilei. He was a corresponding member of the Accademia dei Lincei in Rome.

Kepler has acquired a popular image as an icon of scientific modernity and a man before his time; science popularizer Carl Sagan described him as "the first astrophysicist and the last scientific astrologer".

Early years

5 Mark DDR 1971 - 400. Geburtstag von Johannes Kepler - Bildseite
5 Mark DDR 1971
Homage to Johannes Kepler in Tel Aviv University
Homage to Johannes Kepler in Tel Aviv University

Kepler was born on December 27, the feast day of St John the Evangelist, 1571, in the Free Imperial City of Weil der Stadt (now part of the Stuttgart Region in the German state of Baden-Württemberg.

He was introduced to astronomy at an early age, and developed a love for it that would span his entire life. At age six, he observed the Great Comet of 1577, writing that he "was taken by [his] mother to a high place to look at it." In 1580, at age nine, he observed another astronomical event, a lunar eclipse, recording that he remembered being "called outdoors" to see it and that the moon "appeared quite red". However, childhood smallpox left him with weak vision and crippled hands, limiting his ability in the observational aspects of astronomy.

In 1589, after moving through grammar school, Latin school, and seminary at Maulbronn, Kepler attended Tübinger Stift at the University of Tübingen. There, he studied philosophy and theology, while he was a student, until he became Chancellor at Tübingen in 1590.

He proved himself to be a superb mathematician and earned a reputation as a skilful astrologer, casting horoscopes for fellow students. From 1583 to 1631, he learned both the Ptolemaic system and the Copernican system of planetary motion. He became a Copernican at that time. In a student disputation he maintained that the Sun was the principal source of motive power in the universe.

Despite his desire to become a minister, near the end of his studies, Kepler was recommended for a position as teacher of mathematics and astronomy at the Protestant school in Graz. He accepted the position in April 1594, at the age of 23.

Writings by Kepler

Brahe kepler
Monument of Tycho Brahe and Johannes Kepler in Prague
  • Mysterium cosmographicum (The Sacred Mystery of the Cosmos) (1596)
  • Astronomia nova (New Astronomy) (1609)
  • Epitome astronomiae Copernicanae (Epitome of Copernican Astronomy) (published in three parts from 1618-1621)
  • Harmonice Mundi (Harmony of the Worlds) (1619)
  • Mysterium cosmographicum (The Sacred Mystery of the Cosmos) 2nd Edition (1621)
  • Tabulae Rudolphinae (Rudolphine Tables) (1627)
  • Somnium (The Dream) (1634)


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