Did Johannes Kepler Plot the Death of Tycho Brahe?

Published February 25, 2019 by .

2,256 words, estimated reading time 9 minutes.

Did Johannes Kepler Plot the Death of Tycho Brahe?

Tycho Brahe died suddenly more than 400 years ago and there's been a mystery around if he fell victim to natural causes or was murdered.

Ever since Tycho Brahe died suddenly more than 400 years ago, there has been a mystery about whether the Dane whose observations laid the groundwork for modern astronomy fell victim to natural causes or was murdered.

Who was Tycho Brahe?

Tycho Brahe (1546-1601) was a Dutch astronomer known for his accurate astronomical observations. Born into nobility, Brahe benefited from an excellent education at the University of Copenhagen (at the age of 12) where he studied law. Whilst at the University Brahe was exposed to the works of Aristotle, and from this teaching, was probably introduced to astronomy and cosmology. A year later, in 1560, he experienced a solar eclipse which had been predicted (albeit a day late) by Christopher Clavius. It was this prediction which probably sparked Brahe's interest in astronomy. A few years later whilst travelling in Europe, he witnessed the conjunction of Jupiter and Saturn. It was this conjunction that made him realise just how inaccurate the current prediction methods were, and that astrometric predictions require extensive and accurate observations.

Brahe wearing the Order of the Elephant by Eduard Ender (1822-1883)
Brahe wearing the Order of the Elephant by Eduard Ender (1822-1883) 

Having returned from his travels, Brahe was convinced that he wanted to unlock the secrets of the skies. After the death of his father in 1571, Brahe set up his first observatory at Herrevad Abbey, where he observed a "Stella Nova" in the constellation of Cassiopeia. Over the course of a year, he studied the phenomena and published his findings. This paper would set him firmly on the course to become a world-famous astronomer.

Uraniborg - Tycho's Observatory in Denmark
Uraniborg - Tycho's Observatory in Denmark

Over the next couple of decades, Brahe moved around from Holland to Germany to Prague. He attended royal courts and continued his studies reconciling the Copernican system and the Ptolemaic system into his own Tychonic system. Brahe liked the heliocentric Copernican system but didn't agree with the physics involved. The Ptolemaic system, on the other hand, had better physics but didn't agree with his observations. During this work, Brahe hired a new assistant, a young Johannes Kepler, who was charged with observations of Mars and it's orbit.

Shortly thereafter, Brahe became ill at a banquet in Prague and contracted a urinary condition and died a few days later. Johannes Kepler who was there to record an account wrote that Brahe refused to break etiquette and leave the banquet to relieve himself. He believed it would have been rude of him to leave the banquet. At the time his death was attributed to a kidney stone by contemporary physician James Wittich. Kepler would now take over Brahe's job as court astronomer to the emperor Rudolf II.

Who was Johannes Kepler?

Johannes Kepler (1571-1630) was a German mathematician and astronomer and a huge influence for the astronomical revolution of the 17th century. He is most famous for his study of, and subsequent laws of planetary motion. Unlike Brahe, Kepler was born into poverty.

Kepler's career began as a mathematics teacher in Graz, Austria, but his love for astronomy began many years earlier. When he was six years old, his mother took him outside to see the Great Comet of 1577. This was the first event that sparked his love for astronomy. At the age of 23, Kepler accepted the position of mathematics teacher at the Protestant school in Graz. It was during his time at Graz he published his first paper, Mysterium Cosmographicum (1596), in which he describes his theory on the geometry of the structure of the universe. It was the first piece of work supporting the heliocentric system since Copernicus 50 years previous.

Johannes Kepler (1571 - 1630)
Johannes Kepler (1571 - 1630) 
The Great comet of 1577, seen over Prague on November 12. Engraving made by Jiri Daschitzky.
The Great comet of 1577, seen over Prague on November 12. Engraving made by Jiri Daschitzky.

It was through this work that Kepler and Brahe would be introduced. Kepler wrote to many other astronomers seeking their opinions on the Mysterium Cosmographicum. One of these, Nicolaus Reimers Bar, was a rival to Brahe and republished the letter to advance a personal dispute between himself and Brahe. Despite this Brahe wrote to Kepler criticizing his lack of numerical accuracy which was taken from Copernicus. Despite this, the two corresponded frequently on a number of subjects, data accuracy being one of them. Brahe held accurate observations and recording to be a vital part of any research. The issue of inaccurate data was always an issue for Kepler as he had no accurate observations, and without Brahe's observatory, he would be unable to resolve the issues.

In 1600 the two met during the construction of Brahe's observatory near Prague. Kepler stayed with Brahe as a guest and analysed some of Brahe's work on Mars. This relationship eventually culminated in Kepler being hired as Brahe's assistant at the observatory to record data on Mars orbits. This allowed him to gather the data he required for his Cosmographicum. After Brahe's unexpected death in 1601, Kepler took his place as an imperial mathematician and was commanded to complete his unfinished work.

Statue of Johannes Kepler (left) and Tycho Brahe (right) in Prague
Statue of Johannes Kepler (left) and Tycho Brahe (right) in Prague

Evidence for Murder of Tycho Brahe

Contemporary writing at the time from physician James Wittich would indicate that Brahe's death was attributed to a kidney stone. Kepler wrote that Brahe would not excuse himself from the banquet as doing so would be a breach of etiquette. This action would damage his bladder and he was unable to urinate. For five days he suffered insomnia, fever and delirium until he passed some water, albeit blocked. He then began to recover, he regained strength, was talking to family and friends, the fever was gone and it looked like he was going to make a full recovery. This, however, was not to be the case. After a short, while his strength again ran out and shortly thereafter, on October 24th, he passed away.

Rumours quickly spread across Europe claiming that Brahe had been poisoned. Brahe had previously been known for his robust constitution, and his sudden illness and death was seen as suspicious. However, the writings of Wittich were eventually accepted as the knowledge of medicine at the time was somewhat limited.

It wouldn't be until 1901 when the crypt Brahe was entombed in was to be renovated. 1901 marked the 300th anniversary of his death and the city of Prague decided to refurbish the crypt. They decided to open the tomb and check to see if he was still inside. During the Battle of the White Mountain in 1620, many non-Catholic burials were vandalised. On top of this, some of the repair work to the church over the years had been of poor quality. When they opened the crypt, the found that it had indeed been damaged over the course of time.

They found the coffins of two individuals, both heavily damaged. The first was the coffin of a woman, believed to be that of Kirsten, Brahe's wife. The second contained the remains of a male. Examination showed damage to the skull around the nose and the teeth showed the level of abrasion expected in a man of Brahe's age. It was the remains of Brahe. The crypt was restored, and the bones cleaned and interred in the church. Some of his clothing and hair was removed to be kept at the National Museum of Prague.

In 1955, Danish urologist Edvard Gotfredsen was to examine the kidney stone theory. He was not convinced that the kidney stones were the cause of death since kidney stones very rarely cause blockages, and that burst bladders are extremely rare and only occur after trauma. He notes that the bladder is an extremely tough organ and very difficult to damage. He further notes that no kidney stones were recovered during the 1901 examination of Brahe's burial. He puts forward an alternative theory that an enlarged prostate gland caused the blockage, although the symptoms would have been far more gradual, taking months not days to develop. It was also noted that the inability to urinate would cause swelling in Brahe's abdomen, a symptom not written in any of the accounts.

In 1991 during a repatriation ceremony, the Dutch ambassador was given a sample of Brahe's moustache. The ambassador then gave this sample to the Tycho Brahe Planetarium in Copenhagen where it was further sent to Institute of Forensic Medicine at the University of Copenhagen for analysis. The results of this analysis found the there were normal levels of arsenic and lead, but the level of mercury was much time more than expected. Brahe was a keen alchemist so elevated levels or heavy metals were to be expected, but the levels of mercury we too high to be explained by this. The results of the analysis concluded that the levels of mercury found in the hair samples were of a lethal dose and most probably caused by mercury poisoning shortly before the banquet. Mercury poisoning symptoms include Impairment of peripheral vision, Disturbances in sensations, Lack of coordination, weakness, Insomnia, kidney effects, respiratory failure and death. These all seem to match with accounts of the last days before Brahe's death. Most academics remained sceptical, however, believing that the mercury was left over from the embalming process.

In 1996 the hair was analysed again, this time by Jan Pallon of the University of Lund using a method of chemical analysis involving high energy proton beams. This analysis was called PIXE, short for particle-induced x-ray emission. This method not only analyses the composition of a sample but also the location within the sample. The analysis of one hair showed that there were high levels of mercury, supporting the 1991 examination, and also that the mercury was close to the hair root. He was also able to determine that the mercury was concentrated inside the strand of hair, indicating that it was not contaminated, but grown. By noting the position of the mercury and it's proximity to the hair root, he was able to calculate that mercury was given to Brahe approximately 13 hours before he died. These findings rule out the embalming theory that mercury was left from the embalming process. The findings also raise another question, if the mercury was given to Brahe 13 hours before he died, why did his symptoms last nearly two weeks before? The 1991 analysis showed that mercury was found in Brahe's moustache before the banquet, while the 1996 analysis showed that mercury was not present after 13 hours before his death. What was going on? In order to solve this, they had to look at the samples of hair again, specifically where each was taken. The first samples were taken from Brahe's moustache hair cut from the original 1901 samples. They did not contain the roots. The 1996 analysis was performed on the root of the hair, much closer to the time of death.

One theory put forward by Joshua Gilder (author of Heavenly Intrigue) claims to explain the events being observed here. One poisoning at before the banquet and another 13 hours before his death. Gilder notes that this closely matches with the symptoms of Brahe's illness. It would explain how Brahe had gotten better before becoming severely ill again. Was he then poisoned a second time when it looked like he was going to recover?

Certainly, all the signs are pointing to mercury poisoning, but who was behind it? Did Brahe poison himself with one of his alchemical elixirs? This is unlikely as Brahe was one of the top alchemists of the time and he would be undoubtedly aware of Paracelsus "The dose makes the poison" He would also have known how excruciatingly painful mercury poisoning would be. So who would have had the motive and opportunity to kill Brahe?

Tycho Brahe's Skeleton, November, 2010
Tycho Brahe's Skeleton, November, 2010 

Subsequent analysis of Brahe's hair was conducted in 2010 when Brahe was exhumed again. A Danish-Czeck team conducted a thorough investigation into his death. They took samples from his beard, bones and teeth and analysed them using different techniques. Each result came back the same. The levels of Mercury were not present in sufficient concentrations to cause death, and he had not been exposed to significant concentrations in the last 10 years of his life.

Why Would Kepler Plot to Kill Tycho Brahe?

The first and most obvious motive for Kepler murdering Brahe is the fact that Kepler stood to inherit Brahe's job as an imperial mathematician for Rudolf II, Holy Roman Emperor of Prague. With this came the title, property and observatory. Kepler was born into poverty, so the opportunity to launch himself into nobility must have been tempting. Kepler would also have had access to Brahe and his lab. Kepler certainly had much to gain from the death of Brahe.

Who else would have had motives and opportunity? One of the household staff? It was known the Brahe's staff travelled with him from Denmark when he was exiled, but in the 17th century, the relationship between a master and servant was almost total reliance. To kill the master meant almost certain lack of food, water, clothing and home.

Did any of the Danish nobility who forced Brahe into exile still harbour a grudge? Was Brahe assassinated by the imperial court?

Another possible person with a motive is Brahe's own cousin, Erik Brahe, at the request of the Danish King Christian IV. Under the previous king Brahe had experienced great wealth and popularity in the court, but when he died, the new king was not so favourable and Brahe had to abandon his island. It was speculated that in revenge for this he had an affair with Christians mother. Was this a motive?

We shall, unfortunately, probably never know the actual answer to these questions, nor will we know if Kepler plotted the death of Brahe.

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