Johannes Kepler Timeline

(1571 – 1630)

Johannes Kepler (1571–1630) was a German astronomer, mathematician, and astrologer who played a pivotal role in the 17th-century Scientific Revolution. He is best known for his three laws of planetary motion, which described the elliptical orbits of planets around the Sun and laid the foundation for Isaac Newton's theory of universal gravitation. Kepler worked closely with Tycho Brahe and later served as Imperial Mathematician to Emperor Rudolf II. More Less

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Early Life and Education

Kepler born in Weil der Stadt

Dec 27, 1571

Johannes Kepler was born in the Free Imperial City of Weil der Stadt in the Holy Roman Empire, in what is now Baden-Württemberg, Germany. He was a sickly child but showed remarkable mathematical ability from an early age.

Image source: Johannes Kepler

Attends the University of Tübingen

1589 - 1594

Kepler studied at the University of Tübingen, where he was introduced to the Copernican heliocentric system by astronomer Michael Maestlin. His talent for mathematics quickly became evident to his teachers.

Image source: University of Tübingen

Becomes teacher of mathematics in Graz

Apr 1594

Kepler accepted a position as a teacher of mathematics and astronomy at the Protestant school in Graz, Austria, beginning his professional career while continuing his astronomical studies.

Marries Barbara Müller

Apr 27, 1597

Kepler married Barbara Müller in Graz. Their marriage was marked by personal difficulties and the deaths of two of their children in infancy.

Image source: Johannes Kepler

Meets Tycho Brahe near Prague

Feb 4, 1600

Kepler met Tycho Brahe at Benátky nad Jizerou near Prague after being exiled from Graz for his Protestant faith. Brahe possessed the most precise astronomical data ever collected, which would prove essential to Kepler's later discoveries.

Image source: Tycho Brahe

Appointed imperial mathematician after Brahe's death

1601

Following Tycho Brahe's death, Kepler succeeded him as Imperial Mathematician to Emperor Rudolf II, gaining access to Brahe's invaluable observational data.

Image source: Mathematician

Wife Barbara dies

1611

Kepler's wife Barbara died, along with his son Friedrich, plunging him into a period of grief amid the religious turmoil then engulfing Prague.

Appointed mathematician in Linz

1612

Kepler moved to Linz, Austria, where he took up the position of provincial mathematician, completing work begun in Prague and teaching at the local Landschaftsschule.

Image source: Linz

Marries Susanna Reuttinger

Oct 30, 1613

Kepler married his second wife, Susanna Reuttinger, after considering eleven candidates in a famously methodical matchmaking exercise described in a letter.

Scientific Works

Publishes Mysterium Cosmographicum

1596

Kepler published his first major astronomical work, defending the Copernican system and proposing that the orbits of the planets could be explained by nesting the five Platonic solids. This work brought him to the attention of prominent astronomers including Tycho Brahe.

Image source: Mysterium Cosmographicum

Publishes Dioptrice on optics

1611

Kepler published Dioptrice, a foundational work on optics describing the principles of refraction and the design of the telescope, building on Galileo's telescopic discoveries.

Publishes Epitome Astronomiae Copernicanae

1618 - 1621

Published in three volumes between 1618 and 1621, this influential textbook presented heliocentric astronomy systematically and included all three of Kepler's laws of planetary motion.

Image source: Epitome Astronomiae Copernicanae

Publishes Rudolphine Tables

Sep 1627

Kepler completed the Rudolphine Tables, the most accurate star tables and planetary ephemerides of their era, based on Tycho Brahe's observations and his own laws of planetary motion.

Image source: Rudolphine Tables

Somnium published posthumously

1634

Kepler's fictional account of a journey to the Moon, Somnium, was published posthumously by his son Ludwig. It is often considered one of the earliest works of science fiction and offered lunar astronomy consistent with the Copernican system.

Image source: Somnium (novel)

Astronomical Discoveries

Observes supernova now known as Kepler's Supernova

Oct 17, 1604

Kepler observed a brilliant new star in the constellation Ophiuchus. The supernova, later named Kepler's Star, provided evidence against the Aristotelian idea of an unchanging celestial realm.

Image source: Kepler's Supernova

Publishes Astronomia Nova with first two laws of planetary motion

1609

After years of painstaking analysis of Mars's orbit using Brahe's data, Kepler published Astronomia Nova, containing his first law (planets move in ellipses with the Sun at one focus) and second law (planets sweep out equal areas in equal times), revolutionizing astronomy.

Image source: Astronomia nova

States third law of planetary motion in Harmonices Mundi

1619

In Harmonices Mundi (The Harmony of the World), Kepler announced his third law: the square of a planet's orbital period is proportional to the cube of its semi-major axis, linking the motions of all planets mathematically.

Image source: Harmonices Mundi

Predicts transit of Mercury accurately observed by Gassendi

Nov 7, 1631

The Rudolphine Tables enabled Pierre Gassendi to observe the predicted transit of Mercury, a dramatic posthumous vindication of Kepler's methods and laws, as Kepler had died a year earlier.

Image source: Transit of Mercury

Later Life and Legacy

Mother accused of witchcraft

1615

Kepler's mother Katharina was accused of witchcraft in Leonberg, initiating a legal ordeal that consumed much of Kepler's time and energy for years.

Image source: Katharina Kepler

Defends mother successfully in witchcraft trial

1620 - 1621

Kepler personally intervened in his mother's trial, traveling to Württemberg and mounting a vigorous legal defense that secured her release from imprisonment, though she died shortly afterward.

Kepler dies in Regensburg

Nov 15, 1630

Kepler fell ill and died in Regensburg at age 58 while traveling to collect money owed to him. He was buried locally, though his tomb was destroyed during wars in subsequent decades.

Kepler's laws used by Newton in Principia

1687

Isaac Newton demonstrated that Kepler's three laws of planetary motion follow from his law of universal gravitation in the Principia, cementing Kepler's empirical discoveries as foundations of modern physics.

Image source: Philosophiæ Naturalis Principia Mathematica

Kepler's laws used by Newton in Principia

Key Facts

Johannes Kepler was born on December 27, 1571, in Weil der Stadt, in the Holy Roman Empire (present-day Germany).
He discovered his three laws of planetary motion, published between 1609 and 1619, which established that planets orbit the Sun in ellipses rather than perfect circles.
Kepler worked as an assistant to Danish astronomer Tycho Brahe in Prague starting in 1600 and inherited Brahe's precise observational data after his death in 1601.
In 1611, he invented an improved version of the refracting telescope known as the Keplerian telescope, using a convex eyepiece for greater magnification.
His major works include 'Astronomia Nova' (1609) and 'Harmonices Mundi' (1619), which influenced later scientists such as Isaac Newton.

Source

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