What killed Tycho Brahe?

To help with the calculations,he brings in Kepler,a 28-year-old with his own weird model of the universe. Kepler,a devout Lutheran as well as a Copernican,believes that God created cosmic “harmony” by arranging the planets’ orbits around the Sun so that they’re spaced at distances corresponding to certain geometrical figures. Tycho introduces Kepler to the emperor and lobbies for his appointment as imperial mathematician. But before Kepler’s appointment is formalised,Tycho suddenly becomes terribly ill after a banquet and dies 11 days later,at the age of 54.

What killed him? At the time of Tycho’s death,in 1601,the blame fell on his failure to relieve himself while drinking profusely at the banquet,supposedly injuring his bladder and making him unable to urinate. But then,in the 1990s,some hairs from Tycho were separately analysed. Researchers reported elevated levels of mercury,including one brief high dose that was absorbed within 10 minutes during the final 24 hours of his life.

Those findings inspired Heavenly Intrigue: Johannes Kepler,Tycho Brahe,and the Murder Behind One of History’s Greatest Scientific Discoveries,a 2004 book by a pair of married journalists,Joshua Gilder and Anne-Lee Gilder. They argue that the evidence from the hairs points to two incidents of mercury poisoning,one at the time of the banquet and the other just before death,and that Kepler is the prime suspect because he had the means,the motive and the opportunity. As an assistant living at Tycho’s home,Kepler had access to toxic mercury compounds in Tycho’s alchemical lab and could have poisoned him at the time of the banquet,the Gilders write. When Tycho began to recover 10 days later,they reason,Kepler could have administered a second dose because he was one of the few people at the home who saw Tycho the evening before his death.

In his furious arguments with Tycho,Kepler called himself an “uncontrollable spirit” and once told a friend that he felt like attacking Tycho with a sword. Kepler resented Tycho’s higher status and,above all,his refusal to allow access to the full log of observations,including the records of Mars’s movements that Kepler considered essential to demonstrate the validity of his own model of the universe. Kepler tried several schemes to see Tycho’s data—to sneakily “wrest his riches away,” as Kepler put it—but Tycho resisted and forced Kepler to keep working on calculations aimed at supporting the Tychonic cosmology.

“Kepler’s ambition was to prove his vision of the divine architecture of God’s universe,” Joshua Gilder says in an interview. “Every time he feels Tycho is getting in the way,he blows up at him. Is it plausible that Kepler would kill for a vision? I look around the world and see it happening all the time. Kepler had felt himself despised and outcast his whole life. This would make him famous.”

Things ultimately worked out quite nicely for Kepler because he still got the job as imperial astronomer—and the data. Even though Tycho bequeathed the observatory’s logs to his family,Kepler grabbed them first and held on to the crucial Mars records until he and the heirs and the emperor worked out an arrangement allowing him to finish the project of publishing the observations. Kepler never managed to prove his divine-architecture model,but he made his name anyway,thanks to the records and his own hunch that the Sun exerted some kind of pull on the planets. Using Tycho’s data,he formulated his famous three laws of planetary motion and discovered that the planets travelled around the Sun in elliptical,not circular,orbits. If he did commit a crime,it certainly paid.

The other murder suspect is Eric Brahe,a Swedish relative of Tycho’s who was staying at his home. Eric attended the fateful banquet,and his diary contains incriminating entries alluding to his role in the poisoning,says Peter Andersen,a professor of literature at the University of Strasbourg in France. He argues that Eric was hard up for money and was hired for the hit by the new Danish king,Christian IV.

Professor Andersen has several hypotheses explaining the king’s animus. One is that a royal science adviser was a Copernican feuding against Tycho. A more cinematic hypothesis is that Tycho may have been secretly consorting with Christian’s mother,Queen Sophie,and may have been Christian’s father. Professor Andersen argues that the rumours about Tycho’s royal affair contributed to Shakespeare’s Hamlet.

Professor Andersen is requesting that the current Danish royal family allow Christian’s body to be exhumed so that his DNA can be compared with Tycho’s,but don’t expect any immediate results. It took Jens Vellev,the archaeologist at Aarhus University in Denmark who is leading the project,nearly a decade to get permission to exhume Tycho’s body. Professor Vellev suspects that if Tycho was poisoned by mercury,it was from an accidental ingestion in his laboratory or from a medicine administered to treat his urinary problems.