About Johannes Kepler

Johannes Kepler (December 27, 1571 – November 15, 1630) was a German mathematician, astronomer and astrologer, and key figure in the 17th century scientific revolution. He is best known for his eponymous laws of planetary motion, codified by later astronomers based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astrononomy. They also provided one of the foundations for Isaac Newton's theory of universal gravitation.

During his career, Kepler was a mathematics teacher at a seminary school in Graz, Austria, an assistant to astronomer Tycho Brahe, the court mathematician to Emperor Rudolf II, a mathematics teacher in Linz, Austria, and an adviser to General Wallenstein. He also did fundamental work in the field of optics, invented an improved version of the refracting telescope (the Keplerian Telescope), and helped to legitimize the telescopic discoveries of his contemporary Galileo Galilei.

Kepler lived in an era when there was no clear distinction between astronomy and astrology, but there was a strong division between astronomy (a branch of mathematics within the liberal arts) and physics (a branch of natural philosophy). Kepler also incorporated religious arguments and reasoning into his work, motivated by the religious conviction that God had created the world according to an intelligible plan that is accessible through the natural light of reason. Kepler described his new astronomy as "celestial physics", as "an excursion into Aristotle's Metaphysics", and as "a supplement to Aristotle's On the Heavens", transforming the ancient tradition of physical cosmology by treating astronomy as part of a universal mathematical physics.

The patronage in his life

Kepler started working with Tycho who had been supported by Rudolf II, the Holy Roman Emperor. But soon Kepler found himself and Brahe both desperate for funds, that Brahe proposed the composition of a set of astronomical tables bearing Emperor Rudolf II’s name, which project would secure the funding of Kepler. That turned out to be the famous Rudolphine Tables. After Tycho's unexpected death, Kepler was appointed as imperial mathematician to complete the unfinished work, which became Astronomia nova.


Throughout his life, he had many difficulties including his wife’s death, three children’s illness and death, his mother’s witchcraft trial, political troubles between King of Bohemia and Emperor Rudolf II, and legal issues with Tycho’s heirs. To cope with these situations, Kepler kept sending letters to potential patrons in Wuttemberg and Padua while his patron, the Emperor’s support was not satisfactory for his such life.

Astronomia Nova

The Astronomia nova, published in 1609, contains the results of the astronomer Johannes Kepler's ten-year long investigation of the motion of Mars. In English, the full title of his work is the New Astronomy, Based upon Causes, or Celestial Physics, Treated by Means of Commentaries on the Motions of the Star Mars, from the Observations of Tycho Brahe, Gent.[citation needed] Where previous astronomers had relied on geometric models to explain the observed positions of the planets, Kepler sought for and discovered physical causes for planetary motion.[citation needed] Prior to Kepler, Nicolaus Copernicus proposed in 1543 that the Earth and other planets orbit the Sun. Kepler was the first astronomer to prove this conjecture with rigorous scientific arguments. It is recognized as one of the most important works of the Scientific Revolution.

Astronomia nova TP Astronomia nova image

At over 650 pages in English translation, the Astronomia nova is a lengthy and complex work from the perspective of a modern reader.[citation needed] Kepler walks his readers, step by step, through his process of discovery so as to dispel any impression of "cultivating novelty," he says. Kepler bases his investigations upon the observations of Danish astronomer Tycho Brahe.

The 2009 International Year of Astronomy commemorates the 400th anniversary of the publication of this work.

[Source: Wikipedia]


Johannes Kepler

Tycho Brahe

Rudolf II, Holy Roman Emperor