Mercury Murder Mystery: An Analysis of the Demise of Tycho Brahe

On the morning of October 24, 1601, Danish astronomer Tycho Brahe died from a bladder inflammation. He had been invited eleven days earlier to a banquet by his neighbour, Baron Peter von Rosenberg, alongside his student, Johannes Kepler. The men drank a lot, however Tycho held his urine due to etiquette in the presence of the distinguished Rosenberg. Upon returning home, he discovered to his distress that he could no longer urinate. After days of excruciating pain, intestinal fever and long periods of unconsciousness, he died from complications of uraemia and urosepsis. Brahe was the first modern astronomer to base his theories on both observation and conjecture. His instruments were capable of measuring planetary movements to a degree of accuracy never before attempted and used the principle of parallax to show that the Great Comet of 1577 and the 1572 supernova were celestial phenomena. Brahe was a large believer of the geocentric theory, a model of the universe in which Earth lies at the centre, after failing to find evidence of stellar parallax that would show the Earth moved. His work gained him an excellent reputation and soon many aspiring young astronomers fought to work for him, including the notorious Kepler who later used Brahe’s work in his own studies, continuing his legacy.   

A meta-analysis of the death of Tycho Brahe by virtue of the Czech-Danish consortium has been synthesised with the three contemporary accounts of his cause of death, yet the mystery behind his bladder inflammation is arguably no closer to being solved than of the time of Shakespeare, who wrote of Brahe in his 1603 play Hamlet. Whether his demise was simply urologic, or also involved foul play, namely the administration of mercury poising remains unclear. The most recent forensic evidence disfavours the theory that Tycho Brahe was murdered, though there is no evidence as of yet to confirm he did not die a violent death – and suggests that it was his already degenerating health that caused his demise.  

The three accounts of his death are by Kepler, Brahe’s personal physician Johannes Jessenius, and the German doctor Johannes Wittich. While the latter wrote that a stone prevented Brahe from urinating and he died of a burst bladder, Kepler and Jessenius claimed that it was a combination of bladder inflammation, fever and delirium. An obvious question that arises from these accounts is why nobody tried to catheterise Brahe in an effort to facilitate the healing process of his damaged bladder. Jessenius was Brahe’s physician and was no stranger to catheters. He had even written a treatise on which kinds of catheters to use in difficult situations, proposing that those ‘made of horn and made flexible by soaking them in warm water’ would be more effective than the more common wax catheters. Why, in this case, did he not help Brahe? Perhaps this was because somebody did want Brahe dead; Kepler, for example, was certainly a timely suspect. There had been a strong distrust between him and Brahe despite their collaborative work in astronomy. Brahe admired Kepler’s ability to think ‘outside the box’, but he was also protective of his protocols about the positions of stars and planets he had observed for almost 40 years. Kepler threatened to leave Brahe if he continued to hide his protocols around the same time of the banquet invitation, therefore it is possible that the young astronomer lost his patience and poisoned Brahe’s drink in order to finally obtain his life work. Once Kepler had digested all of Brahe’s voluminous data after his death, he elegantly summarised his observations in his famous three laws of planetary motion, published in 1619. Kepler did have a motive, but whether his passion for astronomy was strong enough to spark murder is questionable.  

Forensic research from the twentieth century onwards has enabled archaeologists to use scientific means of investigation to determine whether Kepler was responsible for Brahe’s death. Although the first hair and beard samples were extracted from Brahe’s tomb in 1901, the first real developments in the research of these samples were in 1992 by the Danish forensic scientist Bent Kæmpe, who detected mercury in these hairs, and by the Swedish physicist Jan Pallon four years later. These scientific results were popularised beyond Scandinavia in 2004 with the publication of the book Heavenly Intrigue by Joshua and Anne-Lee Gilder, who supported the theory that Kepler was responsible for Brahe’s murder. More recent findings, on the other hand, seem to denounce this theory and offer different explanations for the presence of mercury in the astronomer’s hair.   

In 2010, the Czech government granted a team of Danish and Czech archaeologists the permission to re-exhume Brahe’s remains from the Church of Our Lady in Prague for modern forensic analysis. Performed over 400 years after his death, Brahe’s autopsy was hoped to evaluate the hypothesis asserted by Heavenly Intrigue that his own student, Kepler, had murdered him. His hairs were studied in an electron microscope, where an accumulation of electron-dense granules were detected in the outer hair scales, measuring 10 nanometres. At these dense areas, an energy dispersive X-ray analysis revealed the presence of mercury, though not in the surface coatings of hairs. This data refutes the murder theory since the distribution of mercury detected by the electron microscope suggests a long-term accumulation of mercury vapour from Brahe’s alchemistic activities. Analysis of his bones revealed further evidence that Brahe was subjected to a long-term exposure of mercury, contrary to what Heavenly Intrigue had claimed. Brahe in 1597 described the detoxication and cleaning of mercury in the production of an elixir, Tychonis, he believed would prevent diseases affecting skin and blood, thus his exposure to mercury can be explained with evidence of the Tychonis elixir. The data, though it disproves the theory that Brahe was poisoned, does not reject that mercury still may have been the cause of his death. His uptake of alcohol at the banquet might have acted as a trigger for the alteration of the mercury’s pharmacokinetics, for instance, but this again is speculation. What the main result of the data suggests is that the mercury on Brahe’s hair came from the environment, and not from a mercury-contaminated drink, further substantiated by the fact that his bone mineralisation was within normal limits. 

A more sensible explanation for Tycho Brahe’s death was that he had other underlying health implications. A recent palaeopathological study of Brahe’s bones, funded by the Ministry of Culture of the Czech Republic, has produced alternative theories about Brahe’s death. Their findings concluded that he potentially suffered from diffuse idiopathic skeletal hyperostosis (DISH), an arthritis mainly of the spine, and obesity. Brahe was a member of the elite; therefore, this prognosis is not surprising considering the strong correlations between DISH sufferers and obese individuals, with those who are members of a high social status. At present, the precise aetiology of DISH is still uncertain. According to the textual accounts of Brahe’s last days, his symptoms were as follows: ‘Urine retention and strong pain’ according to Jessenius, and a loss of consciousness, i.e. coma. In a seventeenth century context, the term ‘coma’ could also refer to a stroke – DISH is associated with an increased risk of stroke. The study’s explanation of acute urinary retention remains loyal to previous urological research, reiterating its symptomology including bladder dysfunction and renal failure, however this bladder dysfunction is attributed to diabetic neuropathy, stroke and benign prostatic hyperplasia, all which are frequent causes of acute urinary retention. The study ultimately attributes both DISH, diabetes and benign prostatic hypertrophy to Brahe’s death, showing that acute urinary retention has a multifactorial aetiology.  

The analysis of Brahe’s demise at present seems to disprove any conspiracy murder theories and favours the explanation that he died due to poor health. It is probable that the timing of Rosenberg’s banquet and his death was a mere coincidence rather than a carefully situated event that served as a setting for murder. On the other hand, Brahe was rather young to suffer from prostatic hypertrophy at only 54 years of age. The murder theory still remains valid; there was not a lack of people who wanted him dead. He had enemies at the Danish court, the nobility in Prague were not pleased with the influence he held over Emperor Rudolph II of Bohemia and Kepler’s wife was also on bad terms with her husband’s teacher. Nonetheless scientific evidence ruled out the cause of death to be murder following hair and bone analyses. There remain plot holes to this murder mystery, and many questions left unanswered. It is probable that Tycho Brahe’s death will never be solved. 

Written by Kat Jivkova 


Jonas, Ludwig, Jaksch, Heiner, Zellmann, Erhard, Klemm, Kerstin I, and Andersen, Peter Hvilshøj. “Detection of Mercury in the 411-year-old Beard Hairs of the Astronomer Tycho Brahe by Elemental Analysis in Electron Microscopy.” Ultrastructural Pathology 36, no. 5 (2012): 312-19. 

Kacki, Sacha, Velemínský, Petr, Lynnerup, Niels, Kaupová, Sylva, Jeanson, Alizé Lacoste, Povýšil, Ctibor, Horák, Martin, Kučera, Jan, Rasmussen, Kaare Lund, Podliska, Jaroslav, Dragoun, Zdeněk, Smolík, Jiří, Vellev, Jens, and Brůžek, Jaroslav. “Rich Table but Short Life: Diffuse Idiopathic Skeletal Hyperostosis in Danish Astronomer Tycho Brahe (1546-1601) and Its Possible Consequences.” PloS One 13, no. 4 (2018): E0195920. 

Rasmussen, K. L, Kučera, J, Skytte, L, Kameník, J, Havránek, V, Smolík, J, Velemínský, P, Lynnerup, N, Bruzek, J, and Vellev, J. “Was He Murdered Or Was He Not?—Part I: Analyses of Mercury in the Remains of Tycho Brahe.” Archaeometry 55, no. 6 (2013): 1187-195. 

Wyner, Lawrence M. “Urologic Demise of Astronomer Tycho Brahe: A Cosmic Case of Urinary Retention.” Urology (Ridgewood, N.J.) 88 (2015): 33-35. 

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