Johannes Kepler

Born on 27 December 1571 in Weil der Stadt in what is now Germany, Johannes Kepler was an astronomer who formulated three laws of planetary motion. Kepler received a Lutheran education at the University of Tübingen. One of his teachers gave him a copy of a book by Nicolaus Copernicus, sparking Kepler’s interest in the heliocentric model. In 1600 Danish astronomer Tycho Brahe invited Kepler to Prague to create astronomical tables based on measurements that Brahe had carefully collected. Brahe died the following year, and Kepler eventually gained access to his colleague’s data and position as imperial mathematician to the Holy Roman emperor. In 1609 Kepler published Astronomia Nova, which included his first two laws of planetary motion; his third law was published in 1619. Kepler observed a supernova (he called it a “new star”) and completed the detailed astronomical tables Brahe had been so determined to produce. Kepler also contributed research in optics and vision. Later in the century Isaac Newton would prove his law of universal gravitation by showing that it could produce Kepler’s orbits.

Editor’s note, 2 January 2018: The article has been updated to correct some historical inaccuracies.

Date in History: 27 December 1571