Tycho Brahe and Johannes Kepler

Brahe was so enthusiastic „Mysterium Cosmographicum“ [„Secret of the World“], Kepler’s debut work, that he invited him to for a visit to Prague.

Brahe hoped to create a new world model with the help of Kepler’s ideas and mathematical skills, which is why he appointed Kepler assistant at the Prague court.

Still this cooperation turned out to be difficult. Kepler, the theorist, and Brahe, the practitioner, were unable to agree on a common world model. Brahe considered the earth as the centre orbited by the sun, which, again, is orbited by the planets. Kepler, on the contrary, supported the Copernican system that considers the sun as the centre, which is orbited by all planets.

Brahe’s sudden death in 1601 also abruptly ended his project of compiling planetary position prediction tables and rules prediction, known as Rudolphine Plates today. It was Kepler who finally completed his master’s work.

Theories have kept on weaving themselves around Brahe’s sudden death. And it was Johannes Kepler who was in the focus of the accusations. He was accused of having poisoned his master to get access to his precious recordings.

In 2012, Professor Ludwig Jonas, who had worked for 40 years at the University of Rostock after finalizing his biology studies here, was able to refute these accusations by means of a facial hair analysis. According to this, mercury was found in the hair only, but not in hair shaft and hair roots. These investigation results indicate long-term poisoning resulting from many years of handling chemicals. The study published by Ludwig Jonas, acquitted Johannes Kepler of assassination, centuries after his death.

Johannes Kepler used Brahe’s recordings for studying the planetary motions of Mars. With these investigations, he intended to plausibly explain the apparent loop movements and to achieve a more precise predictability of planetary positions in a next step. The laws developed by him have remained valid until today.

1. The planetary orbits are ellipses with the sun as focal point.
2. The connection line planet – sun underlines covers same surfaces in the same time.
3. The squares of the planet’s orbital periods are like the cube of their average distance from the sun.

In remembrance of Brahe and Kepler

In the Prague district Hradcany, a bronze sculpture reminds of the achievements of Tycho Brahe and Johannes Kepler.