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tycho brahe, famous astronomers

Happy Birthday, Tycho Brahe, Notable Danish Astronomer

December 14, 2009
by Liz Colville
Tycho Brahe’s perfectionist approach to astronomy and astronomical instruments yielded some of the field’s greatest discoveries.

Tycho Brahe's Early Days

Born Tyge Brahe on December 14, 1546, in a castle in Skane, Denmark (now part of Sweden), Tycho Brahe was the oldest child of noble Danish parents. Raised by his uncle and benefactor, Jörgen Brahe, the young man studied at the University of Copenhagen and the University of Leipzig in Germany. He then moved on to other German universities in Wittenberg, Rostock and Basel, according to the Galileo Project’s biography of Brahe.

Witnessing a solar eclipse in 1560 sparked Brahe’s interest in astronomy; he had previously studied philosophy and rhetoric, according to TychoBrahe.com, an educational site devoted to the astronomer. He started studying astronomy without permission, “but was soon forgiven after demonstrating successes.”

It was at the University of Wittenberg, in 1566, that Brahe lost part of his nose in a duel with a fellow student over who was the better mathematician. “For the rest of his life he wore a metal insert over the missing part.”

Brahe's Notable Accomplishments

Unlike his predecessor, Nicholas Copernicus (1473–1543), Brahe did not believe in a heliocentric (sun-centered) universe, a theory Copernicus laid out in the Copernican system. Brahe argued, as did Aristotle, that Earth was the center of the universe. But his theory was more or less a bridge between the two, according to the Galileo Project: The Tychonic world system, adopted by many astronomers in the 17th century, proposed that the “Moon and Sun revolved about the Earth, and the shell of the fixed stars was centered on the Earth,” but Mercury, Venus, Mars, Jupiter and Saturn revolved around the Sun.

Brahe’s most significant discovery was of a new star in the constellation Cassiopeia in 1572; in 1573 he wrote “On the New and Never Previously Seen Star,” although, like the rest of Brahe’s writings, this was not published in his lifetime. Brahe’s apprentice, Johannes Kepler, later used Brahe’s writings in his own studies.

Brahe also made several influential measurements of a comet observed in Europe in 1577. By this time he was working on the Danish island of Hven at the observatory Uraniburg, funded by King Frederick II of Denmark. His stature and reputation as a builder of instruments helped to change the commonly held idea that comets occurred in the sublunar sphere. Brahe’s measurements suggested that comets were actually “heavenly bodies.” Aristotle’s theory was that the universe consisted of two spheres: the heavens and the sublunary regions, with the heavens being unchanging. Brahe’s measurements of the star and comet helped to gradually erode that line of thinking.

Brahe fell out of favor with the Danish court, but he was able to secure an important position in Prague, serving from 1599 until his death in 1601 as the Imperial Mathematician to Emperor Rudolph II. Brahe had created a printing press at Hven, as well as many instruments, and brought these to his castle in Prague, where he hired Kepler as his apprentice.

The Rest of the Story

Brahe’s meticulous measurements of objects at different stages of their orbits was a revolutionary approach to astronomy that helped pave the way for the more sophisticated conjectures of Kepler, Galileo and others who followed Brahe. Specifically, Kepler used Brahe's observations to develop the theory that the planets move in elliptical orbits.

There are two theories about Brahe’s death on October 24, 1601. The long-held theory was that he died of a bladder infection after failing to relieve himself, out of politeness, while at a banquet in Prague. The episode was described in the 1654 book “Tycho Brahe, the man and his work,” written in Latin by Pierre Gassendi. The passage about the banquet is reproduced on a Web site of a Tycho Brahe society based in Sweden. The second theory is far more recent and backed by scientific research that followed the opening of Brahe’s grave in 1996: researchers found high mercury levels in strands of his hair, indicating mercury poisoning as a possible cause of death.

England’s Museum of the History of Science in Oxford has an online exhibition of images of Brahe, including a 19th-century painting believed to be of Emperor Rudolph II and Brahe.

Information about Tycho Brahe’s written work, which Kepler helped to complete, is available, with images, on a University of Cambridge Web page about astronomy.

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