Tycho Brahe (December 14, 1546 – October 24, 1601) was a Danish astrologer, astronomer, and alchemist. He had Uraniborg built, which became an early "research institute". For purposes of publication, Tycho owned a printing press and paper mill. His best known assistant was Johannes Kepler.
Tycho realized that progress in the science of astronomy could be achieved not by occasional haphazard observations, but only by systematic and rigorous observation, night after night, and by using instruments of the highest accuracy obtainable. He was able to improve and enlarge the existing instruments, and construct entirely new ones. Brahe's naked eye measurements, of planetary parallax were accurate to the arcminute. (These measurements became the possessions of Kepler following Brahe's death.)
While a student, Tycho lost part of his nose in a duel. This occurred in 1566 while the 20-year-old Tycho was studying at the University of Rostock in Germany. Attending a dance at a professor's house, he quarrelled with one Manderup Parsbjerg, a fellow member of the Danish gentry. A subsequent duel (in the dark) resulted in Tycho losing the bridge of his nose. For the rest of his life, he was said to have worn a silver replacement. Tycho's tomb was reopened in 1901 and his remains were examined by medical experts. The nasal opening of the skull was rimmed with green, a sign of exposure to copper, not silver.
In November, 1572, Tycho had observed a very bright star which had unexpectedly appeared in the constellation Cassiopeia. Since it had been maintained since Antiquity that the world of the fixed stars was eternal and unchangeable, other observers held that the phenomenon was something in the Earth's atmosphere. Tycho, however, observed that the parallax of the object did not change from night to night, suggesting that the object was far away. Tycho argued that a nearby object should appear to shift its position with respect to the background. He published a small book, De Stella Nova (1573), thereby coining the term nova for a "new" star. (We now know that Tycho's star was a supernova.) This discovery was decisive for his choice of astronomy as a profession.
Kepler tried, but was unable, to persuade Brahe to adopt the heliocentric model of the solar system. Tycho believed in a modified geocentric model known as the Tychonian system, for the same reasons that he argued that the supernova of 1572 was not near the Earth. He argued that if the Earth were in motion, then nearby stars should appear to shift their positions with respect to background stars. In fact, this effect of parallax does exist; it could not be observed with the naked eye, or even with the telescopes of the next two hundred years, because even the nearest stars are much more distant than most astronomers of the time believed possible.
Uraniborg, Stjerneborg and Benátky nad Jizerou
King Frederick II of Denmark and Norway, impressed with Tycho's 1572 observations, financed the construction of two observatories for Tycho on Ven. These were Uraniborg and Stjerneborg. Uraniborg also had a laboratory for Brahe's alchemical experiments.
Because he disagreed with Christian IV, the new king of his country, he moved to Prague in 1599. Sponsored by Rudolf II, the Holy Roman Emperor, he built a new observatory (in a castle in Benátky nad Jizerou 50 km away from Prague) and worked there until his death.
In return for their support, Brahe's duties included preparing astrological charts and predictions for his patrons on events such as births; weather forecasting; and astrological interpretations of significant astronomical events such as the comet of 1577 and the supernova of 1572.
Tycho was the preeminent observational astronomer of the pre-telescopic period, and his observations of stellar and planetary positions achieved unparalleled accuracy for their time. After his death, his records of the motion of the planet Mars enabled Kepler to discover the laws of planetary motion, which provided powerful support for the Copernican heliocentric theory of the solar system. Tycho himself was not a Copernican, but proposed a system in which the planets other than Earth orbited the Sun while the sun orbited the earth. This system is frequently described as a "compromise"; however, both the heliocentric and geocentric theories relied upon "crystal spheres", to which the planets were attached. Tycho's theory abandoned the crystal spheres, a remarkable step to take before Isaac Newton formulated the concept of "action at a distance". In this respect, then, the Tychonic universe was more revolutionary than the Copernican.
He was aware that a star observed near the horizon appears with a greater altitude than the real one, due to atmospheric refraction, and he worked out tables for the correction of this source of error.
Brahe died in 1601, several days after his bladder burst during a banquet. It has been said that to leave the banquet before it concluded, would be "the height" of bad manners, and so he remained until his bladder exploded.
Recent investigations suppose that Tycho did not die directly of his urinary problems, but may have poisoned himself unintentionally by administering some medicine containing mercury (he pursued alchemical studies as well throughout his life, however he seems either not to have kept records or to have destroyed them).