Mathematician:Johannes Kepler

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German mathematician and astronomer best known nowadays for Kepler's Laws of Planetary Motion.

Inherited the papers of Tycho Brahe and spent many years analysing his observations, looking for patterns.

His most significant contribution to scientific thought was his deduction that the orbits of the planets are elliptical.

Also pre-empted the methods of integral calculus to find the volume of a solid of revolution by slicing it into thin disks, calculating the volume of each, and then adding those volumes together.

The foremost expert of his age on the Conics of Apollonius of Perga.

From an early age accepted the concept of the heliocentric universe of Nicolaus Copernicus rather than the geocentric one of Claudius Ptolemy.

At one point earned a living (reluctantly) as an astrologer, a profession he despised.




  • Born: 27 Dec 1571, Weil der Stadt, Württemberg, Holy Roman Empire (now Germany)
  • 1589: Studied mathematics at the University of Tübingen under Michael Maestlin
  • 1591: Received Master's degree
  • 1594: Obtained position as lecturer in mathematics and astronomy in the Protestant seminary in Graz.
  • 1596: Wrote to Tycho Brahe, sending him a copy of his Mysterium Cosmographicum
  • 1598: Temporarily exiled from Graz on religious grounds
  • 1600: Became assistant to Tycho Brahe in Prague
  • 1601: Took over Tycho Brahe's position as Imperial Mathematician to Emperor Rudolph II. Spent years analysing the orbit of Mars. Took up casting horoscopes in order to make ends meet.
  • 1609: Sent a copy of his Astronomia Nova to Galileo, who failed to recognise its importance
  • 1611: Kepler's son and wife died. Political changes exiled him from Prague.
  • 1613: Remarried
  • Died: 15 Nov 1630, Regensburg (now in Germany)


Results named for Johannes Kepler can be found here.

Definitions of concepts named for Johannes Kepler can be found here.


  • 1596: Mysterium Cosmographicum (The Sacred Mystery of the Cosmos)
  • 1601: De Fundamentis Astrologiae Certioribus (Concerning the More Certain Fundamentals of Astrology)
  • 1604: Astronomiae Pars Optica (The Optical Part of Astronomy)
  • 1604: De Stella Nova in Pede Serpentarii (On the New Star in Ophiuchus's Foot)
  • 1609: Astronomia Nova (New Astronomy) (in which Kepler's First and Second Laws of Planetary Motion appeared)
  • 1610: Tertius Interveniens (Third-party Interventions)
  • 1610: Dissertatio cum Nuncio Sidereo (Conversation with the Starry Messenger)
  • 1611: Dioptrice
  • 1611: De Nive Sexangula (On the Six-Cornered Snowflake)
  • 1613: De Vero Anno, quo Aeternus Dei Filius Humanam Naturam in Utero Benedictae Virginis Mariae Assumpsit
  • 1615: Eclogae Chronicae (published with Dissertatio cum Nuncio Sidereo)
  • 1615: Nova Stereometria Doliorum Vinariorum (New Stereometry of Wine Barrels) (in which the techniques of integral calculus were foreshadowed)
  • 1618 -- 1621: Epitome Astronomiae Copernicanae
  • 1619: Harmonices Mundi (The Harmonies of the World) (in which Kepler's Third Law of Planetary Motion appeared)
  • 1621: Mysterium Cosmographicum (The Sacred Mystery of the Cosmos) (2nd Edition)
  • 1627: Tabulae Rudolphinae (Rudolphine Tables)
  • 1634: Somnium (The Dream)

Notable Quotes

God lives in the details.

Geometry has two great treasures, one is the Theorem of Pythagoras, the other the division of a line into extreme and mean ratio; the first we may compare to a measure of gold, the second we may name a precious jewel.

A mind accustomed to mathematical deduction, when confronted with the faulty foundations of astrology, resists a long, long time, like an obstinate mule, until compelled by beating and curses to put its foot down into that dirty puddle.

Mother Astronomy would certainly starve if daughter Astrology did not earn the bread of both.

Also known as

Some sources give his name as Johann Kepler.