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David Nightingale: Tycho’s Death

Tycho Brahe
Public Domain / Wikicommons

Those giants of astronomy, Tycho Brahe and Johannes Kepler, were both born in the 1500s. It’s never been clearly established how Tycho died, but there have been suspicions that the younger man, Kepler, poisoned him.

Tycho was a nobleman. Sent away to a school in Leipzig [ref.1 p.32]  to study law, his real interests lay in the heavens as well as in chemistry. He was the outsider in a family of statesmen and generals, and he would devote his life to making observations of the positions of stars and planets.

The telescope had not yet been invented, and Tycho’s instruments were sextants and quadrants. He had noticed that the ephemeris tables used by sailors gave star positions that were often quite inaccurate. His own measuring was much better, and this was soon recognized by the Danish king.

At 26, Tycho witnessed the sudden creation of a star where he knew there had been none before [ref.1,p58]  – we would call this a ‘nova’. He was invited to lecture at the Univ. of Copenhagen, and also about this time he fell in love with someone below his noble rank – a vicar’s daughter – and married her. His aristocratic family didn’t recognize his marriage, regarding her merely as a mistress, and so to avoid unpleasantness Tycho made plans to continue his accurate measurements abroad. The king heard of his plans, and not wishing him to him leave Denmark offered him the island of Hven, plus a salary and monies to construct an observatory. Drawings of this castle-like ‘lab’, named Uraniborg, can be seen on the internet.    

Tycho stayed there about 15 years, but kept many of his planetary measurements to himself, which certainly came to irk the young German mathematician Johannes Kepler.

Kepler had been born in poverty, as I described in a 2005 essay. His aggressive mother had been accused of witchcraft, and Kepler described his father as brutal and criminal. His early schooling was in monasteries, and he describes hunger and ill-health as well as a deep self-loathing.

Kepler was accepted to the theological seminary at Tubingen in south-west Germany, and always top of the class in mathematics he began working on a sun-centered model of the heavens, as opposed to Tycho’s earth-centered universe.

So how did their paths cross? By the time Tycho was in his fifties and famous, and Uraniborg had become history, Tycho was in Prague as the Holy Roman Emperor’s mathematician/astronomer. Kepler, frequently down on his luck, had unhappily accepted Tycho’s offer to be his assistant; and all this has been fully described in a stimulating book by Gilder [ref.1].

Now Kepler had more than once asked Tycho for his accurate planetary data, and more than once had even insulted his benefactor. Nevertheless the easy-going Tycho kept him on, while guarding his data, intending to publish later.

In 1601 Tycho was at one of the Emperor’s banquets but needing to relieve himself badly. Unwilling to defy court decorum he remained seated. His bladder ruptured, and he died some days later.

In 2010 Tycho’s tomb was opened, and very high levels of mercury were detected in Tycho’s hair. Did his assistant Kepler have a hand in possible mercury poisoning?

To complicate matters, suspicion was also cast on others, who may have administered mercury at the request of the then new young Danish king, whose mother was rumored to have been having an affair with Tycho.

After Tycho’s 1601 death, Kepler was able to study the crucial data, and came up with his three famous laws of planetary motion, laws that pre-date Newton.

Studies are still being made, using X-ray instruments on Tycho’s hair, [iPIXE; ibid p. 216] to try to clear up how Tycho died.


 1.  “Heavenly Intrigue” by Joshua Gilder and Anne-Lee Gilder; Doubleday, a division of Random House, Inc, NY, (2004).

David Nightingale is Professor of Emeritus of Physics at the State University of New York at New Paltz. His latest book is A Kitchen Course in Electricity and Magnetism, published by Springer, New York.

The views expressed by commentators are solely those of the authors. They do not necessarily reflect the views of this station or its management.

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