Review

Johannes Kepler discovered his third planetary law 400 years ago - his home address in Linz has also been discovered.

On May 15, 1618 Johannes Kepler discovered his third planetary law in Linz:

"The squares of the orbital times of the planets around the sun are related
like the third powers of their mean distances from the sun. "

This fundamental law applies not only to the movement of planets around the sun, but also to all bodies that move around a much larger mass, e.g. B. exoplanets around stars or satellites that orbit the earth. In Linz, Kepler had observed several lunar eclipses and made detailed records of his observation results. From these observations, Erich Meyer from the Linz Astronomical Community was able to locate the house in which Kepler lived when he made this discovery. So far it was only known that Kepler had lived in Hofgasse, now it is certain that he lived with his family in Hofgasse 7. A newly installed plaque reminds:

"The astronomer Johannes Kepler lived here from 1613 to 1620 and wrote important works such as 'Harmonices mundi' with the famous third law."

I.a. the American space agency NASA published the Keplerhaus in Linz on May 15, 2018 as 'Astronomy Picture of the Day'.

The third planetary law was published by Kepler in 1619 in the fifth book of the Harmonices mundi (world harmonics).
The Kepler Society, together with the Universities of Stuttgart and Tübingen, will be honoring this event in the coming year with a series of events entitled "400 Years of World Harmony".