About Tycho Brahe

Tycho Brahe, Danish astronomer 14/12 1546 - 24/10 1601

Born: 14 Dec 1546 in Knudstrup, Denmark
Died: 24 Oct 1601 in Prague, Bohemia (now Czech Republic)

Tycho Brahe, a Danish aristocrat turned astronomer, invented a system in which the earth is stationary and the planets revolve around the sun which, in turn, revolves around the earth. This model replaced that of Ptolemy, which had the planets revolving around the earth, with epicycles accounting for their retrograde motion. This model was favored by most astronomers until the mid-seventeenth century. It had the advantage of avoiding the problems introduced by ascribing motion to the Earth, which was obviously not moving.

Tycho Brahe's most important studies, however, concerned the supernova of 1572, which appeared as a new star in the constellation Cassiopeia. He argued that it was at a great distance from the earth, and not merely a local phenomenon, using the absence of a parallax as evidence. The star is now usually known as 'Tycho's supernova'. This work, together with his observations of the comet of 1577, enabled him to destroy the hypothesis of solid celestial spheres.

With financial help from the King of Denmark, he built an observatory on the island of Hveen in Copenhagen Sound. The observatory, called Uraniborg, was equipped with exceptionally large and accurate instruments (and with an alchemical laboratory in its basement). At Uraniborg Tycho made twenty years' worth of astronomical observations, all without telescopes, which did not come into use until later.

In 1599 he was appointed Imperial Mathematician to the Holy Roman Emperor, Rudolph II, in Prague. Johannes Kepler (1571 -1630) joined him as an assistant, to help with mathematical calculations. Kepler, unlike Tycho, was a follower of Copernicus, who put the sun at the center of the solar system.


Thanks to John J O'Connor and Edmund F Robertson of the School of Mathematical and Computational Sciences, University of St Andrews, St Andrews, Scotland, who maintain the MacTutor History of Mathematics Archive:

http://www-groups.dcs.st-and.ac.uk/~history/ from which this information is derived. Thanks also to the Institute and Museum of the History of Science of Florence, Italy, for the image of Tycho Brahe.

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Last updated: 12/17/96, comments to: tycho@eecs.berkeley.edu