Editing Tycho Brahe (section)

==Life==
[[File:Jacques de Gheyn Ii - Portrait of Tycho Brahe, astronomer (without a hat) - Google Art Project.jpg|thumb|[[Jacob de Gheyn II|Jacques de Gheyn]]: Tycho Brahe framed by the family shields of his noble ancestors, 1586.]]
[[File:Tycho Brahe - Stellarum octavi orbis inerrantium accurata restitutio, 1598. Author's portrait (Tycho Brahe portrait, cropped).jpg|thumb|Tycho Brahe: ''Stellarum octavi orbis inerrantium accurata restitutio'', 1598. Author's portrait in this book.]]
[[File:Tycho Brahe - Dedication to Josephus Scaliger of Astronomiae instauratae mechanica, 1598 (signature, cropped).jpg|thumb|Signature on a book dedication to [[Josephus Scaliger]], around 1598.]]

===Family===
Tycho Brahe was born as heir to several of Denmark's most influential noble families. In addition to his immediate ancestry with the [[Brahe]] and the [[Bille (noble family)|Bille families]], he counted the Rud, [[Trolle]], [[Ulfstand]], and [[Rosenkrantz (noble family)|Rosenkrantz]] families among his ancestors. Both of his grandfathers and all of his great-grandfathers had served as members of the Danish king's [[Riksråd|Privy Council]]. His paternal grandfather and namesake, Thyge Brahe, was the lord of [[Tosterup Castle]] in Scania and died in battle during the 1523 Siege of Malmö during the Lutheran Reformation Wars.{{sfn|Håkansson|2006|pp=39{{ndash}}40}}

His maternal grandfather, [[Claus Bille]], lord to [[Bohus Fortress|Bohus Castle]] and a second cousin of Swedish king [[Gustav I of Sweden|Gustav Vasa]], participated in the [[Stockholm Bloodbath]] on the side of the Danish king against the Swedish nobles. Tycho's father, [[Otte Brahe]], a royal Privy Councilor (like his own father), married [[Beate Clausdatter Bille|Beate Bille]], a powerful figure at the Danish court holding several royal land titles. Tycho's parents are buried under the floor of the church of [[Kågeröd]], four kilometres west of [[Knutstorp Castle]].{{sfn|Håkansson|2006|pp=39{{ndash}}40}}

===Early years===
Tycho was born on 14 December 1546,{{sfn|Hoskin|1997|p=98}} at his family's ancestral seat at [[Knutstorp Castle|Knutstorp]] ({{lang|da|Knudstrup borg}}; {{lang|sv|Knutstorps borg}}), about {{convert|8|km}} north of [[Svalöv Municipality|Svalöv]] in then Danish [[Scania]]. He was the oldest of 12 siblings, 8 of whom lived to adulthood, including [[Steen Ottesen Brahe (1547–1620)|Steen Brahe]] and [[Sophia Brahe]]. His twin brother died before being [[baptized]]. Tycho later wrote an ode in Latin to his dead twin,{{sfn|Wittendorff|1994|p=68}} which was printed in 1572 as his first published work. An [[epitaph]], originally from Knutstorp, but now on a plaque near the church door, shows the whole family, including Tycho as a boy.

When he was only two years old Tycho was taken away to be raised by his uncle [[Jørgen Thygesen Brahe]] and his wife [[Inger Oxe]], sister to [[Peder Oxe]], Steward of the Realm, who were childless. It is unclear why Otte Brahe reached this arrangement with his brother, but Tycho was the only one of his siblings not to be raised by his mother at Knutstorp. Instead, Tycho was raised at Jørgen Brahe's estate at [[Tosterup Castle|Tosterup]] and at [[Tranekær]] on the island of [[Langeland]], and later at Næsbyhoved Castle near [[Odense]], and later again at the Castle of [[Nykøbing Falster|Nykøbing]] on the island of [[Falster]]. Tycho later wrote that Jørgen Brahe "raised me and generously provided for me during his life until my eighteenth year; he always treated me as his own son and made me his heir".{{sfn|Håkansson|2006|p=40}}

From ages 6 to 12, Tycho attended Latin school, probably in Nykøbing. At age 12, on 19 April 1559, Tycho began studies at the [[University of Copenhagen]]. There, following his uncle's wishes, he studied law, but also studied a variety of other subjects and became interested in [[astronomy]]. At the university, [[Aristotle]] was a staple of scientific theory, and Tycho likely received a thorough training in [[Aristotelian physics]] and cosmology. He experienced the [[solar eclipse of August 21, 1560|solar eclipse of 21 August 1560]], and was greatly impressed by the fact that it had been predicted, although the prediction based on current observational data was a day off. He realized that more accurate observations would be the key to making more exact predictions. He purchased an [[ephemeris]] and books on astronomy, including [[Johannes de Sacrobosco]]'s {{lang|la|[[De sphaera mundi]]}}, [[Petrus Apianus]]'s {{lang|la|Cosmographia seu descriptio totius orbis}} and [[Regiomontanus]]'s {{lang|la|De triangulis omnimodis}}.{{sfn|Håkansson|2006|p=40}}

Jørgen Thygesen Brahe, however, wanted Tycho to educate himself in order to become a civil servant, and sent him on a study tour of Europe in early 1562. Fifteen-year-old Tycho was given as mentee to the 19-year-old [[Anders Sørensen Vedel]]. Tycho eventually talked Vedel into allowing him to pursue astronomy during the tour.{{sfn|Bricka|1888|p=608}} Vedel and his pupil left Copenhagen in February 1562. On 24 March, they arrived in [[Leipzig]], where they matriculated at the Lutheran [[Leipzig University]].{{sfn|Dreyer|1890|p=16}} In 1563, he observed [[Great conjunction#1563|a close conjunction]] of the planets [[Jupiter]] and [[Saturn]], and noticed that the Copernican and Ptolemaic tables used to predict the conjunction were inaccurate. This led him to realise that progress in astronomy required systematic, rigorous observation, night after night, using the most accurate instruments obtainable. He began maintaining detailed journals of all his astronomical observations. In this period, he combined the study of astronomy with [[astrology]], laying down horoscopes for different famous personalities.{{sfn|Håkansson|2006|p=45}}

When Tycho and Vedel returned from Leipzig in 1565, Denmark was at [[Northern Seven Years' War|war with Sweden]], and as vice-admiral of the Danish fleet, Jørgen Brahe had become a national hero for having participated in the sinking of the [[Swedish warship Mars|Swedish warship ''Mars'']] during the [[First battle of Öland (1564)]]. Shortly after Tycho's arrival in Denmark, Jørgen Brahe was defeated in the [[action of 4 June 1565]], and shortly afterwards died of a fever. Stories have it that he contracted pneumonia after a night of drinking with the Danish King [[Frederick II of Denmark|Frederick II]] when the king fell into the water in a Copenhagen canal and Brahe jumped in after him. Brahe's possessions passed on to his wife Inger Oxe, who considered Tycho with special fondness.{{sfn|Håkansson|2006|p=46}}

===Tycho's nose===
In 1566, Tycho left to study at the [[University of Rostock]] in what is now [[Germany]]. There he studied with professors of medicine at the university's famous medical school and became interested in medical [[alchemy]] and [[herbal medicine]].<ref>{{cite web |title=Immatrikulation von Tycho Brahe |url=http://purl.uni-rostock.de/matrikel/100028187 |website=[[Rostock Matrikelportal]] |publisher=[[University of Rostock]] |access-date=21 December 2022 |archive-url=https://web.archive.org/web/20221221102550/http://matrikel.uni-rostock.de/id/100028187 |archive-date=21 December 2022 |page=|trans-title=Matriculation of Tycho Brahe |language=de}}</ref> On 29 December 1566 at the age of 20, Tycho lost part of his nose in a sword [[duel]] with a fellow Danish nobleman, his third cousin [[Manderup Parsberg]]. At an engagement party at the home of Professor [[Lucas Bacmeister (theologian)|Lucas Bachmeister]] on 10 December the two had drunkenly quarreled over who was the superior mathematician.{{sfn|Benecke|2004|p=6}} On 29 December, the cousins resolved their feud with a duel in the dark. Though the two were later reconciled, in the duel Tycho lost the bridge of his nose and gained a broad scar across his forehead.{{sfn|Boerst|2003|pp=34{{ndash}}35}}

He received the best possible care at the university and wore a prosthetic nose for the rest of his life. It was kept in place with [[wheatpaste|paste]] or glue and said to be made of silver and gold.{{sfn|Boerst|2003|pp=34{{ndash}}35}} In November 2012, Danish and Czech researchers reported that the prosthesis was actually made of [[brass]] after chemically analyzing a small bone sample from the nose from the body exhumed in 2010.<ref name="Gan">{{cite news |last1=Gannon |first1=Megan |title=Tycho Brahe Died from Pee, Not Poison |url=http://www.livescience.com/24835-astronomer-tycho-brahe-death.html |access-date=21 December 2022 |work=[[LiveScience]] |date=16 November 2012}}</ref> The prostheses made of gold and silver were mostly worn for special occasions, rather than everyday wear.

===Science and life on Uraniborg===
{{Main|Uraniborg}}

In April 1567, Tycho returned home from his travels, with a firm intention of becoming an astrologer. Although he had been expected to go into politics and the law, like most of his kinsmen, and although Denmark was still at war with Sweden, his family supported his decision to dedicate himself to the sciences. His father wanted him to take up law, but Tycho was allowed to travel to [[Rostock]] and then to [[Augsburg]], where he built a great [[quadrant (instrument)|quadrant]], then [[Basel]], and [[Freiburg im Breisgau|Freiburg]]. In 1568, he was appointed a [[canon (priest)|canon]] at [[Roskilde Cathedral]], a largely honorary position that allowed him to focus on his studies.{{sfn|Christianson|2000|pp=8{{ndash}}14}}

At the end of 1570, he was informed of his father's ill health, so he returned to Knutstorp Castle, where his father died on 9 May 1571. The war was over, and the Danish lords soon returned to prosperity. Soon, another uncle, Steen Bille, helped him build an observatory and alchemical laboratory at [[Herrevad Abbey]], where Tycho was assisted by his keenest disciple, his younger sister [[Sophia Brahe|Sophie Brahe]].{{sfn|Christianson|2000|pp=8{{ndash}}14}} Tycho was acknowledged by King Frederick II, who proposed to him that an observatory be built to better study the night sky. After accepting this proposal, the location for the Uraniborg's construction was set on an island called [[Ven (Sweden)|Hven, now Ven]] in the Sound not too far from Copenhagen,<ref name="Van">{{cite web |last1=Van Helden |first1=Al |title=Tycho Brahe (1546–1601) |url=http://galileo.rice.edu/sci/brahe.html |website=The Galileo Project |publisher=[[Rice University]] |access-date=21 December 2022 |archive-url=https://web.archive.org/web/20221205205214/http://galileo.rice.edu/sci/brahe.html |archive-date=5 December 2022 |date=1995}}</ref> the earliest large observatory in Christian Europe.{{sfn|Hoskin|1997|p=98}}

Tycho Brahe was highly appreciated by [[Frederick II of Denmark|King Frederick II]], and he was accepted and supported by people of high social status. He was supported by the church. The support Tycho Brahe received from the king allowed him to continue his research and make significant contributions to the field of astronomy.

In the late 16th century, Tycho Brahe built an observatory called Uraniborg. It was built on the island of Hven located between the provinces of Zealand (Sjælland) and Scania (Skåne). The island was then an administrative part of Zealand. Later, after the [[Treaty of Roskilde|Peace of Roskilde]] in 1658, Scania was conquered by the Swedes. In 1660, Hven became part of Sweden. In Tycho's time, it was all Denmark. He lived on Hven for approximately 21 years. He began to build Uraniborg in 1576 and moved there soon after. As Uraniborg was a significant and advanced observatory, it took years to complete.<ref>Christianson, J. R. (2020). "Star Castle: Going Down to See Up". In ''Tycho Brahe and the measure of the heavens'' (pp. 118–159). essay, Reaktion Books.</ref>

Uraniborg was a place where Tycho Brahe could research and analyze his previous findings, as well as explore new discoveries. Tycho Brahe was an astronomer of the pre-telescope era. Using just his naked eye, he observed the planets, Moon, stars, and space and recorded everything he saw while completing a multitude of calculations daily. The location of Uraniborg was strategically chosen, with seclusion and support being the primary reasons for building on the island of Hven. Seclusion was essential for accurate observation, and gave Tycho Brahe a better way to focus on his work without worrying about interruptions from other people. Seclusion was also important for observation, as there was nothing interfering with time, light, or motion observations.<ref>Christianson, J. R. (2020). "Star Castle: Going Down to See Up". In ''Tycho Brahe and the measure of the heavens'' (pp. 118–159). essay, Reaktion Books.</ref>

Tycho Brahe was a perfectionist, and by being secluded he had complete control over his research and was not limited by anyone else's restrictions, enabling him to develop innovative research. He could focus all of his energy on his work, without receiving any backlash or questioning from anyone. The seclusion gave him the freedom to pursue his research without limitations and paved the way for groundbreaking discoveries in the field of astronomy. Uraniborg was one of the most advanced observatories of its time, equipped with several astronomical instruments, including quadrant instruments, sextants, and astronomical clocks.<ref>Christianson, J. R. (2020). "Star Castle: Going Down to See Up". In ''Tycho Brahe and the measure of the heavens'' (pp. 118–159). essay, Reaktion Books.</ref>

Tycho Brahe's observations and calculations at Uraniborg allowed him to develop more accurate [[Solar System]] models. He compiled the most extensive and accurate catalog of stellar positions up to that time. Tycho Brahe's observations and calculations at Uraniborg allowed him to lay the groundwork for astronomers in the future.<ref>Christianson, J. R. (2020). "Star Castle: Going Down to See Up". In ''Tycho Brahe and the measure of the heavens'' (pp. 118–159). essay, Reaktion Books.</ref> 

Despite the success Tycho Brahe had on Hven, he eventually left the island after a disagreement with the new king of Denmark, Christian IV. In 1597, Tycho Brahe moved to Prague, where he continued his work and was eventually appointed by Emperor Rudolf II in 1601 as imperial mathematician.<ref>{{cite book|url=https://books.google.com/books?id=-h5FAAAAIAAJ&q=brahe|title=The Follies of Science at the Court of Rudolph II: 1576–1612|last=Bolton|first=Henry Carrington|pages=78, 85|place=Milwaukee|publisher=Pharmaceutical Review Publishing Co.|year=1904}}</ref> However, Uraniborg remained a significant landmark in the history of astronomy. 

====Morganatic marriage to Kirsten Jørgensdatter====
Towards the end of 1571, Tycho fell in love with Kirsten, daughter of Jørgen Hansen, the [[Lutheranism|Lutheran]] minister in Knudstrup.{{sfn|Thoren|Christianson|1990|p=45}} As she was a [[commoner]], Tycho never formally married her, since if he did he would lose his noble privileges. However, [[Courts of Denmark|Danish law]] permitted [[morganatic marriage]], which meant that a nobleman and a common woman could live together openly as husband and wife for three years, and their alliance then became a legally binding marriage. However, each would maintain their social status, and any children they had together would be considered commoners, with no rights to titles, landholdings, coat of arms, or even their father's noble name.{{sfn|Christianson|2000|pages=12–14}} 

While King Frederick respected Tycho's choice of wife, himself having been unable to marry the woman he loved, many of Tycho's family members disagreed, and many churchmen continued to hold the lack of a divinely sanctioned marriage against him. Kirsten Jørgensdatter gave birth to their first daughter, Kirstine, named after Tycho's late sister, on 12{{nbsp}}October 1573. Kirstine died from the plague in 1576. Tycho wrote a heartfelt elegy for her tombstone.{{sfn|Björklund|1992}} In 1574, they moved to Copenhagen where their daughter Magdalene was born.{{sfn|Christianson|2000|page=60}} Later the family followed him into exile.{{sfn|Christianson|2000|page=207}} Kirsten and Tycho lived together for almost thirty years until Tycho's death. Together, they had eight children, six of whom lived to adulthood.

[[File:Tycho Cas SN1572.jpg|thumb|A star map of the constellation [[Cassiopeia (constellation)|Cassiopeia]] showing the position of the [[SN 1572|supernova of 1572]], the topmost star, labelled ''I'', from Tycho Brahe's {{lang|la|De nova stella}}|alt=Star map of the constellation Cassiopeia showing the position of the supernova of 1572 (the topmost star, labelled I); from Tycho Brahe's De nova stella.|upright=0.85]]

====1572 supernova====
[[File:Brahe-6.jpg|alt=Title page to De nova stella, in a facsimile reprint of the original 1573 edition (1901)|thumb|The title page to ''De nova stella'', in a facsimile reprint of the original 1573 edition, 1901]]
On 11 November 1572, Tycho observed, from Herrevad Abbey,  a very bright star, now numbered [[SN 1572]], which had unexpectedly appeared in the constellation [[Cassiopeia (constellation)|Cassiopeia]]. Because it had been maintained since [[Ancient history|antiquity]] that the world beyond the Moon's orbit was eternally unchangeable, with celestial immutability being a fundamental axiom of the [[Aristotelianism|Aristotelian]] world-view, other observers held that the phenomenon was something in the terrestrial sphere below the Moon. However, Tycho observed that the object showed no daily [[Diurnal parallax|parallax]] against the background of the fixed stars. This implied that it was at least farther away than the Moon and those planets that do show such parallax. He found that the object did not change its position relative to the fixed stars over several months, as all planets did in their periodic orbital motions, even the outer planets, for which no daily parallax was detectable.{{sfn|Christianson|2000|pages=17–18}}{{sfn|Thoren|Christianson|1990|pp=55–60}}

This suggested that it was not even a planet, but a fixed star in the stellar sphere beyond all the planets. In 1573, he published a small book {{lang|la|De nova stella}},<ref>[http://www.texts.dnlb.dk/DeNovaStella/Index.html ''De nova et nullius ævi memoria prius visa stella'']. {{webarchive|url=https://web.archive.org/web/20090224211014/http://www.texts.dnlb.dk/DeNovaStella/Index.html |date=24 February 2009 }} – Photocopy of the Latin print with a partial translation into Danish: {{lang|da|"Om den nye og aldrig siden Verdens begyndelse i nogen tidsalders erindring før observerede stjerne&nbsp;..."}}</ref><ref>{{Cite book |last=Brahe |first=Tycho |url=https://books.google.com/books?id=X71OAQAAMAAJ&dq=De+nova+stella&pg=PR7 |title=De nova stella: summi civis memor denuo |date=1901 |language=la}}</ref> coining the term [[nova]] for a "new" star. This star was a [[supernova]] and is 7,500&nbsp;[[light-year]]s from Earth. This discovery was decisive for his choice of astronomy as a profession. Tycho was strongly critical of those who dismissed the implications of the astronomical appearance, writing in the preface to {{lang|la|De nova stella}}: {{lang|la|"O crassa ingenia. O caecos coeli spectatores"}} ("O thick wits. O blind watchers of the sky"). The publication of his discovery made him a well-known name among scientists in Europe.{{sfn|Christianson|2000|pages=17–18}}{{sfn|Thoren|Christianson|1990|pp=55–60}}

====Lord of Hven====
Tycho continued with his detailed observations, often assisted by his first assistant and student, his younger sister [[Sophia Brahe|Sophie]]. In 1574, Tycho published the observations made in 1572 from his first observatory at Herrevad Abbey. He then started lecturing on astronomy, but gave it up and left Denmark in spring 1575 to tour abroad. He first visited [[William IV, Landgrave of Hesse-Kassel]]'s observatory at Kassel, then went on to Frankfurt, Basel, and Venice, where he acted as an agent for the Danish king, contacting artisans and craftsmen whom the king wanted to work on his new palace at Elsinore. Upon his return, the King wished to repay Tycho's service by offering him a position worthy of his family. He offered him a choice of lordships of militarily and economically important estates, such as the castles of [[Hammershus]] or [[Helsingborg]].{{sfn|Christianson|2000|p=8}}{{sfn|Hoskin|1997|p=98}}

Tycho was reluctant to take up a position as a lord of the realm, preferring to focus on his science. He wrote to his friend Johannes Pratensis, "I did not want to take possession of any of the castles our benevolent king so graciously offered me. I am displeased with society here, customary forms and the whole rubbish".{{sfn|Christianson|2000|p=8}} Tycho secretly began to plan to move to Basel, wishing to participate in the burgeoning academic and scientific life there. The King heard of Tycho's plans, and desiring to keep the distinguished scientist,{{sfn|Christianson|2000|pp=7–8, 25–27}} in 1576 he offered Tycho the island of [[Hven]] in [[Øresund]] and funding to set up an observatory.{{sfn|Hoskin|1997|p=98}}

{{multiple image
 | direction = horizontal
| total_width = 440
 | header =
 | footer =
 | image1 = Tycho-Brahe-Mural-Quadrant.jpg
 | alt1 =
 | caption1 = Tycho Brahe's large mural quadrant at [[Uraniborg]]
 | image2 = Tycho_Brahe%27s_Stjerneborg.jpg
 | alt2 =
 | caption2 = An engraving of the above ground parts of Tycho Brahe's underground observatory, [[Stjerneborg]]
 }}

Until then, Hven had been property directly under the Crown. The 50 families on the island considered themselves to be freeholding farmers, but with Tycho's appointment as Feudal Lord of Hven, this changed. Tycho took control of agricultural planning, requiring the peasants to cultivate twice as much as they had done before, and he exacted [[corvée]] labor from the peasants for the construction of his new castle.{{sfn|Christianson|2000|pp=28{{ndash}}39}} The peasants complained about Tycho's excessive taxation and took him to court. The court established Tycho's right to levy taxes and labor. The result was a contract detailing the mutual obligations of lord and peasants on the island.{{sfn|Christianson|2000|pp=40–43}}

Tycho envisioned his castle [[Uraniborg]] as a temple dedicated to the [[muse]]s of arts and sciences, rather than as a military fortress. It was named after [[Urania]], the muse of astronomy. Construction began in 1576, with a laboratory for his [[alchemy|alchemical]] experiments in the cellar. Uraniborg was inspired by the Venetian architect [[Andrea Palladio]]. It was one of the first buildings in northern Europe to show influence from Italian renaissance architecture.

When he realized that the towers of Uraniborg were not adequate as observatories, because of the instruments' exposure to the elements and the movement of the building, he constructed an underground observatory close to Uraniborg called [[Stjerneborg]] (Star Castle) in 1584. This consisted of several hemispherical crypts which contained the great equatorial armillary, large azimuth quadrant, zodiacal armillary, largest azimuth quadrant of steel and the trigonal sextant.{{sfn|Christianson|2000|p=108}}

The basement of Uraniborg included an alchemical laboratory, with 16 furnaces for conducting distillations and other chemical experiments.{{sfn|Shackelford|1993}} Unusually for the time, Tycho established Uraniborg as a research centre, where almost 100 students and artisans worked from 1576 to 1597.{{sfn|Christianson|2000|p=247}} Uraniborg contained a printing press and a paper mill, both among the first in Scandinavia, enabling Tycho to publish his own manuscripts, on locally made paper with his own [[watermark]]. He created a system of ponds and canals to run the wheels of the paper mill.{{sfn|Christianson|2000|p=142}} Another resident of Uraniborg was a man with [[dwarfism]] named Jeppe, whom Tycho believed had the ability to predict the future, and he allegedly was able to correctly predict the chances of recovery or death of ill people in Hven.<ref>{{cite web|url=https://www.peterbeard.net/tycho-brahe-at-hven.html |title=
Tycho Brahe at Hveen|last=Beard|first=Peter |website=peterbeard.net |access-date=26 July 2024}}</ref>

Over the years he worked on Uraniborg, Tycho was assisted by a number of students and protegés, many of whom went on to their own careers in astronomy. Among them were [[Christian Sørensen Longomontanus]], later one of the main proponents of the Tychonic model and Tycho's replacement as royal Danish astronomer, Peder Flemløse, Elias Olsen Morsing, and [[Cort Aslakssøn]]. Tycho's instrument-maker Hans Crol formed part of the scientific community on the island.{{sfn|Christianson|2000|p=142}}

[[File:Brahe notebook.jpg|thumb|Brahe's notebook with his observations of the 1577 comet]]

==== Great Comet of 1577 ====
Tycho observed the [[Great Comet of 1577|great comet]] that was visible in the Northern sky from November 1577 to January 1578. Within Lutheranism, it was commonly believed that celestial objects like comets were powerful portents, announcing the coming apocalypse. Several Danish amateur astronomers observed the object and published prophesies of impending doom. Tycho was able to determine that the comet's distance to Earth was much greater than the distance of the Moon, so that the comet could not have originated in the "earthly sphere", confirming his prior anti-Aristotelian conclusions about the fixed nature of the sky beyond the Moon.{{sfn|Christianson|1979}}

Tycho realized that the comet's [[Comet tail|tail]] was always pointing away from the Sun. He calculated its diameter, mass, and the length of its tail, and speculated about the material it was made of. Through nightly observations of the comet, Tycho Brahe estimated its closest approach to Earth at about 230 times the Earth's radius. He also analyzed its motion, suggesting an orbit located between Mercury and Venus.<ref name=":0">{{Cite journal |last=Yavari Ayin |first=Mostafa |date=2023 |title=Defenseless eyes against the sky. A narrative of some astronomical observations before the invention of the telescope |journal=Nojum Magazine [Iranian Magazine of Astronomy] |volume=32 |issue=4 |pages=36–41}}</ref>

At this point, he had not yet broken with [[Copernican heliocentrism]], and observing the comet inspired him to try to develop an alternative Copernican model, in which the Earth was immobile.{{sfn|Christianson|1979}} Tycho Brahe's comet observations challenged the prevailing theory of solid celestial spheres. With the comet likely traveling between Mercury and Venus, the notion of these rigid spheres became untenable. It suggested a vast emptiness where objects like the comet, potentially quite large, could move freely and exhibit properties unlike those previously understood.<ref name=":0" /> The second half of his manuscript about the comet dealt with the astrological and apocalyptic aspects of the comet. Tycho rejected the prophesies of his competitors. Instead, he made his own predictions of dire political events in the near future.{{sfn|Håkansson|2004}} Among his predictions was bloodshed in Moscow, and the imminent fall of [[Ivan the Terrible]] by 1583.{{refn|1=Ivan the Terrible died a year later than predicted by Tycho Brahe{{sfn|Christianson|1979}}|group=note}}

==== Support from the Crown ====
The support that Tycho received from the Crown was substantial, amounting to 1% of the annual total revenue at one point in the 1580s.{{sfn|Thoren|Christianson|1990|p=188}} Tycho often held large social gatherings in his castle. [[Pierre Gassendi]] wrote that Tycho had a tame [[Moose|elk]] and that his mentor the [[Landgrave]] Wilhelm of [[Landgraviate of Hesse-Kassel|Hesse-Kassel]] asked whether there was an animal faster than a deer. Tycho replied that there was none, but he could send his tame elk. When Wilhelm replied he would accept one in exchange for a horse, Tycho replied with the sad news that the elk had just died on a visit to entertain a nobleman at [[Landskrona]]. Apparently, during dinner, the elk had drunk a lot of beer, fallen down the stairs, and died.{{sfn|Dreyer|1890|p=210}}

Among the many noble visitors to Hven was [[James VI and I|James VI of Scotland]], who married the Danish princess [[Anne of Denmark|Anne]]. He gave gold coins to the ferryman and to the builders and workers at Tycho's paper mill.{{sfn|Kerr-Peterson|Pearce|2020|p=45}} After his visit to Hven in 1590, James wrote a poem comparing Tycho with Apollon and [[Phaethon]].{{sfn|Christianson|2000|p=141}}

As part of Tycho's duties to the Crown, in exchange for his estate, he fulfilled the functions of a royal astrologer. At the beginning of each year, he had to present an Almanac to the court, predicting the influence of the stars on the political and economic prospects of the year. At the birth of each prince, he prepared their horoscopes, predicting their fates. He also worked as a cartographer with his former tutor Anders Sørensen Vedel on mapping out all of the Danish realm.{{sfn|Håkansson|2006|p=62}} An ally of the king and friendly with [[Sophie of Mecklenburg-Güstrow|Queen Sophie]], both his mother Beate Bille and adoptive mother Inger Oxe had been her court maids, he secured a promise from the King that ownership of Hven and Uraniborg would pass to his heirs.{{sfn|Christianson|2000|p=141}}

====Publications, correspondence and scientific disputes====
[[File:Astronomiae Instauratae Progymnasmata.jpg|thumb|The [[Book frontispiece|frontispiece]] of the 1610<!--The date indicated in the Wikicommons file says "1609", but the cover of the book itself says "1610".--> edition of {{lang|la|Astronomiae Instauratae Progymnasmata}}]]
In 1588, Tycho's royal benefactor died, and a volume of Tycho's great two-volume work {{lang|la|Astronomiae Instauratae Progymnasmata}} (''Introduction to the New Astronomy'') was published. The first volume, devoted to the new star of 1572, was not ready, because the reduction of the observations of 1572–73 involved much research to correct the stars' positions for [[atmospheric refraction|refraction]], [[axial precession|precession]], the motion of the Sun etc., and was not completed in Tycho's lifetime. It was published in Prague in 1602–1603.{{sfn|Christianson|1979}}

The second volume, titled {{lang|la|De Mundi Aetherei Recentioribus Phaenomenis Liber Secundus}} (''Second Book About Recent Phenomena in the Celestial World'') and devoted to the comet of 1577, was printed at Uraniborg and some copies were issued in 1588. Besides the comet observations, it included an account of Tycho's system of the world.{{sfn|Christianson|1979}} The third volume was intended to treat the comets of 1580 and following years in a similar manner. It was never published, or written, though a great deal of material about the comet of 1585 was put together and published in 1845 with the observations of this comet.{{sfn|Dreyer1890|pp=162–163}}

While at Uraniborg, Tycho maintained correspondence with scientists and astronomers across Europe.{{sfn|Mosley|2007|p=36}} He inquired about other astronomers' observations and shared his own technological advances to help them achieve more accurate observations. Thus, his correspondence was crucial to his research. Often, correspondence was not just private communication between scholars, but also a way to disseminate results and arguments and to build progress and scientific consensus. Through correspondence, Tycho was involved in several personal disputes with critics of his theories. Prominent among them were [[John Craig (physician)|John Craig]], a Scottish physician who was a strong believer in the authority of the Aristotelian worldview, and [[Nicolaus Reimers|Nicolaus Reimers Baer]], known as Ursus, an astronomer at the Imperial court in Prague, whom Tycho accused of having plagiarized his cosmological model.{{sfn|Håkansson|2006|pp=179–189}}

Craig refused to accept Tycho's conclusion, that the comet of 1577 had to be located within the aetherial sphere, rather than within the atmosphere of Earth. Craig tried to contradict Tycho by using his own observations of the comet, and by questioning his methodology. Tycho published an ''apologia'' (a defense) of his conclusions, in which he provided additional arguments, as well as condemning Craig's ideas in strong language for being incompetent. Another dispute concerned the mathematician [[Paul Wittich]], who, after staying on Hven in 1580, taught Count Wilhelm of Kassel and his astronomer [[Christoph Rothmann]] to build copies of Tycho's instruments without permission from Tycho. Craig, who had studied with Wittich, accused Tycho of minimizing Wittich's role in developing some of the trigonometric methods used by Tycho. In his dealings with these disputes, Tycho made sure to leverage his support in the scientific community, by publishing and disseminating his own answers and arguments.{{sfn|Håkansson|2006|pp=179–189}}

===Exile and later years===
{{Quote box |width=300px |align=right|quoted=true |
|salign=right
|quote=<poem>Denmark what is my offense? How
have I offended  my fatherland?
You may think that what I have done is wrong
But was I wrong to spread your fame abroad?
Tell me, who has done such things before?
And sung your honor to the very stars?</poem>
|source=Excerpt of Tycho Brahe's ''Elegy to Dania''{{sfn|Christianson|2000|page=216}}
}}
When Frederick died in 1588, his son and heir [[Christian IV of Denmark|Christian IV]] was only 11 years old. A regency council was appointed to rule for the young prince-elect until his coronation in 1596. The head of the council (Steward of the Realm) was [[Christoffer Valkendorff]], who disliked Tycho after a conflict between them, and hence Tycho's influence at the Danish court steadily declined. Feeling that his legacy on Hven was in peril, he approached the Dowager Queen Sophie and asked her to affirm in writing her late husband's promise to endow Hven to Tycho's heirs.{{sfn|Christianson|2000|p=141}} 

He realized that the young king was more interested in war than in science, and was of no mind to keep his father's promise. King Christian IV followed a policy of curbing the power of the nobility, by confiscating their estates to minimize their income bases, by accusing nobles of misusing their offices and of heresies against the Lutheran church. Tycho, who was known to sympathize with the [[Philippists]], followers of [[Philip Melanchthon]], was among the nobles who fell out of grace with the new king. The king's unfavorable disposition towards Tycho was likely also a result of efforts by several of his enemies at court to turn the king against him.{{sfn|Björklund|1992}}

In addition to Valkendorff, Tycho's enemies included the king's doctor Peter Severinus, who also had personal gripes with Tycho. Several [[gnesio-Lutheran]] Bishops suspected Tycho of heresy{{snd}}a suspicion motivated by his known Philippist sympathies, his pursuits in medicine and alchemy, both of which he practiced without the church's approval, and his prohibiting the local priest on Hven to include the exorcism in the baptismal ritual. Among the accusations raised against Tycho were his failure to adequately maintain the royal chapel at Roskilde, and his harshness and exploitation of the Hven peasantry.{{sfn|Björklund|1992}}

[[File:Titelblad till bok om astronomi av Tycho Brahe, 1648 - Skoklosters slott - 99889.tif|thumb|The title page of {{lang|la|Astronomiae Instauratae, 1648 edition.}}]]
Tycho became even more inclined to leave when a mob of commoners, possibly incited by his enemies at court, rioted in front of his house in Copenhagen. Tycho left Hven in 1597, bringing some of his instruments with him to Copenhagen, and entrusting others to a caretaker on the island. Shortly before leaving, he completed his star catalogue giving the positions of 1,000 stars.{{sfn|Björklund|1992}} After some unsuccessful attempts at influencing the king to let him return, including showcasing his instruments on the wall of the city, he acquiesced to exile. He wrote his most famous poem, ''Elegy to Dania'' in which he chided Denmark for not appreciating his genius.{{sfn|Björklund|1992|p=33}}<ref name="Bra">{{cite web |last1=Brashear |first1=Ronald |title=Tycho Brahe: Astronomiæ instauratæ (1602) |url=http://www.sil.si.edu/DigitalCollections/HST/Brahe/brahe-introduction.htm#book |website=Smithsonian Libraries |publisher=[[Smithsonian Institution]] |access-date=19 July 2016 |date=1999}}</ref>

The instruments he had used in Uraniborg and Stjerneborg were depicted and described in detail in his [[star catalogue]] {{lang|la|Astronomiae instauratae mechanica}} or ''Instruments for the restoration of astronomy'', first published in 1598. The King sent two envoys to Hven to describe the instruments left behind by Tycho. Unversed in astronomy, the envoys reported to the king that the large mechanical contraptions such as his large quadrant and sextant were "useless and even harmful".{{sfn|Björklund|1992|p=33}}<ref name="Bra">{{cite web |last1=Brashear |first1=Ronald |title=Tycho Brahe: Astronomiæ instauratæ (1602) |url=http://www.sil.si.edu/DigitalCollections/HST/Brahe/brahe-introduction.htm#book |website=Smithsonian Libraries |publisher=[[Smithsonian Institution]] |access-date=19 July 2016 |date=1999}}</ref>

From 1597 to 1598, he spent a year at the castle of his friend [[Heinrich Rantzau]] at Haus Wandesburg in [[Wandsbek]] outside [[Hamburg]]. Then they moved for a while to [[Wittenberg]], where they stayed in the former home of Philip Melanchthon.{{sfn|Håkansson|2006|p=68}}

In 1599, he obtained the patronage of [[Rudolf II, Holy Roman Emperor]] and moved to Prague, as Imperial Court Astronomer. Tycho built a new observatory in a castle in [[Benátky nad Jizerou]], 50&nbsp;km from Prague, and worked there for one year. The emperor then brought him back to Prague, where he stayed until his death. At the imperial court even Tycho's wife and children were treated like nobility, which they had never been at the Danish court.{{sfn|Håkansson|2006|p=68}}

Tycho received financial support from several nobles in addition to the emperor, including Oldrich Desiderius Pruskowsky von Pruskow, to whom he dedicated his famous {{lang|la|Mechanica}}. In return for their support, Tycho's duties included preparing [[astrological chart]]s and predictions for his patrons at events such as births, [[weather forecasting]], and astrological interpretations of significant astronomical events, such as the supernova of 1572, sometimes called Tycho's supernova, and the Great Comet of 1577.<ref>Adam Mosley and the Department of History and Philosophy of Science of the [[University of Cambridge]]. [http://www.hps.cam.ac.uk/starry/tychoastrol.html "Tycho Brahe and Astrology"]. {{Webarchive|url=https://web.archive.org/web/20111208234739/http://www.hps.cam.ac.uk/starry/tychoastrol.html |date=8 December 2011 }}. 1999. Retrieved 2 October 2008</ref>

====Relationship with Kepler====
{{Main|Johannes Kepler}}

In Prague, Tycho worked closely with Kepler, his assistant. Kepler was a convinced Copernican, and considered Tycho's model to be mistaken, and derived from simple "inversion" of the Sun's and Earth's positions in the Copernican model.{{sfn|Jardine|2006|p=258}} Together, the two worked on a new star catalogue based on his own accurate positions{{snd}}this catalogue became the ''[[Rudolphine Tables]]''.{{sfn|Taton|Wilson|1989}} Also at the court in Prague was the mathematician Nicolaus Reimers (Ursus), with whom Tycho had previously corresponded, and who, like Tycho, had developed a geo-heliocentric planetary model, which Tycho considered to have been plagiarized from his own.{{sfn|Jardine|2006}}{{sfn|Mosley|2007|p=28}}{{sfn|Ferguson|2002}}

Kepler had previously spoken highly of Ursus, but now found himself in the problematic position of being employed by Tycho and having to defend his employer against Ursus' accusations, even though he disagreed with both of their planetary models. In 1600, he finished the tract {{lang|la|Apologia pro Tychone contra Ursum}} (defense of Tycho against Ursus).{{sfn|Jardine|2006}}{{sfn|Mosley|2007|p=28}}{{sfn|Ferguson|2002}} Kepler had great respect for Tycho's methods and the accuracy of his observations and considered him to be the new [[Hipparchus]], who would provide the foundation for a restoration of the science of astronomy.{{sfn|Christianson|2000|p=304}}

===Illness, death, and investigations===
Tycho suddenly contracted a bladder or kidney ailment after attending a banquet in Prague. He died eleven days later, on 24 October 1601, at the age of 54. According to Kepler's first-hand account, Tycho had refused to leave the banquet to relieve himself because it would have been a breach of etiquette.{{sfn|Thoren|Christianson|1990|pp=468–469}} After he returned home, he was no longer able to urinate, except eventually in very small quantities and with excruciating pain. The night before he died, he suffered from a [[delirium]] during which he was frequently heard to exclaim that he hoped he would not seem to have lived in vain.{{sfn|Dreyer|1890|p=309}} 

Before dying, he urged Kepler to finish the ''Rudolphine Tables'' and expressed the hope that he would do so by adopting Tycho's own planetary system, rather than that of the [[polymath]] [[Nicolaus Copernicus]]. It was reported that Tycho had written his own epitaph, "He lived like a sage and died like a fool."<ref>{{cite web |title=Brahe, Tycho (1546–1601) |url=http://scienceworld.wolfram.com/biography/Brahe.html |website=Eric Weisstein's World of Scientific Biography |publisher=Eric W. Weisstein |access-date=13 August 2012}}</ref> A contemporary physician attributed his death to a [[kidney stone]], but no kidney stones were found during an [[autopsy]] performed after his body was exhumed in 1901. Modern medical assessment is that his death was more likely caused by either a burst bladder,<ref>{{Cite web|url=https://www.nbcnews.com/id/wbna49858043|title=Astronomer Tycho Brahe died of burst bladder, not poisoning|date=16 November 2012|website=NBC News|accessdate=4 August 2023}}</ref> [[prostatic hypertrophy]], acute [[prostatitis]], or [[prostate cancer]], which led to [[urinary retention]], [[overflow incontinence]], and [[uremia]].{{sfn|Gotfredsen|1955}}{{sfn|Wyner|2015}}

Investigations in the 1990s suggested that Tycho may not have died from urinary problems, but instead from [[mercury poisoning]].<ref>Kaempe, Thykier, Pedersen. "The cause of death of Tycho Brahe in 1601". ''Proceedings of the 31st TIAFT Congress, Leipzig 1993, Contributions to Forensic Toxicology''. Molina Press, Leipzig 1994, pp.{{nbsp}}309–315</ref> It was speculated that he had been intentionally poisoned. The two main suspects were his assistant, [[Johannes Kepler]], whose motives would be to gain access to Tycho's laboratory and chemicals,{{sfn|Gilder|Gilder|2005}} and his cousin, Erik Brahe, at the order of friend-turned-enemy [[Christian IV]], because of rumors that Tycho had had an affair with Christian's mother.

In February 2010, the Prague city authorities approved a request by Danish scientists to exhume the remains, and in November 2010 a group of Czech and Danish scientists from [[Aarhus University]] collected bone, hair and clothing samples for analysis.<ref>{{cite news| url = http://www.cphpost.dk/culture/culture/122-culture/48128-tycho-brahe-to-be-exhumed.html| title = Tycho Brahe to be exhumed| date = 4 February 2010| newspaper = [[The Copenhagen Post]]| access-date = 27 May 2010| archive-date = 11 August 2011| archive-url = https://web.archive.org/web/20110811035807/http://www.cphpost.dk/culture/culture/122-culture/48128-tycho-brahe-to-be-exhumed.html| url-status = dead}}</ref><ref>{{cite web| url =http://humaniora.au.dk/en/events/tychobrahetomb/| archive-url =https://web.archive.org/web/20101023035446/http://humaniora.au.dk/en/events/tychobrahetomb/| url-status =dead| archive-date =23 October 2010| title =The opening of Tycho Brahe's tomb| date =21 October 2010| publisher =[[Aarhus University]]| access-date =27 October 2010}}</ref> The scientists, led by Jens Vellev, analyzed Tycho's beard hair once again. The team reported in November 2012 that there was not enough mercury present to substantiate murder, and there were no lethal levels of any poisons present. The team's conclusion was that "it is impossible that Tycho Brahe could have been murdered".<ref name="BBC2012">{{cite news |title=Astronomer Tycho Brahe 'not poisoned', says expert |url=https://www.bbc.co.uk/news/science-environment-20344201 |access-date=15 November 2012 |work=[[BBC News]] |date=15 November 2012}}</ref><ref>{{Cite magazine|url=https://newsfeed.time.com/2012/11/17/was-tycho-brahe-poisoned-according-to-new-evidence-probably-not/ |title=Was Tycho Brahe Poisoned? According to New Evidence, Probably Not|magazine=[[Time (magazine)|Time]] |date=17 November 2012|access-date=17 November 2012}}</ref> 

The findings were confirmed by scientists from the University of Rostock, who examined a sample of Tycho's beard hairs that had been taken in 1901. Although traces of mercury were found, these were present only in the outer scales. Therefore, mercury poisoning as the cause of death was ruled out. The study suggests that the accumulation of mercury may have come from the "precipitation of mercury dust from the air during [Tycho's] long-term alchemistic activities".<ref>{{cite journal |title=Detection of mercury in the 411-year-old beard hairs of the astronomer Tycho Brahe by elemental analysis in electron microscopy |last1=Jonas |first1=Ludwig |last2=Jaksch |first2=Heiner |last3=Zellmann |first3=Erhard |last4=Klemm |first4=Kerstin I. |last5=Andersen |first5=Peter Hvilshøj |journal=[[Ultrastructural Pathology]] |date=2012 |volume=36 |issue=5 |pages=312–319 |pmid=23025649 |doi=10.3109/01913123.2012.685686|s2cid=21440099 }}</ref> 

Tycho is buried in the [[Church of Our Lady before Týn]], in [[Old Town Square (Prague)|Old Town Square]] near the [[Prague Astronomical Clock]].