BRAHE,TYCHO (1546-1601),
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Danish astronomer, the discoverer of the "new star" in Cassiopeia andand one ofthe great practical astronomers of the later Renaissance, was born on Dec. 14, 1546, at the family seat of Kundstrup in Scania, Den. he studied at Copenhagen, Leipzig, Rostock and Augsburg, and in 1571 was permitted by his maternal uncle, Steno Belle, to install a laboratory at his castle of Herritzvad, near Kunstrup, where on Nov. 11, 1572, he discovered the famous "new star" in the costellation Cassiopeia. His observations were published in De Nova Stella (1573), in which he proved that the star was beyond the moon, contrary to the general belief.
He gave lectures in Copenhagen, by royal command, in 1574 and traveled to Germanyand Italy in 1575. he returned to Denmark in the following year when Frederick II granted him the island of Hven, near Copenhagen, together with ample means to found an observatory there. In return, Tycho acted as astrologer and almanac maker for the royal family. The corner stone of Uraniborg ("castle of the sky") was laid in 1576 and the finished building provided working spaces, living quarters and instrumentson a scale much greater than had previously been available to astronomers. Uraniborg, together with a later building, Stellaborg, is the forerunner of the great modern observatories.
The apearance of the new star in 1572 had given Tycho the idea of forming a precise star catalogue which, together with most of his other work, was carried out on Hven between 1576 and1596. In 1596 Frederick was Succeeded by Christian IV who was less tolerant to Tycho's arrogance and heavy drain on the royal treasury. Tycho's pensions having been withdrawn, he left Denmark in 1597 and finally reached Prague in June 1599, where he was assured of favour and protection by the emperor Rudolph II, who granted him the castle of Benatky, near Prague, together with an ample pension. Although most of his instruments were moved from Hven to Prague, and Kepler joinedhim in Jan. 1600, very few observatons were made and Tycho died there on Oct. 24, 1601.
Tycho's principal work, Astrnomiae instauratae Progymnasmata, 2 vol. (1602-03), was edited by Kepler. The first volume treated of the motions of the Sun and Moon and gave the places of the 777 fixed stars -- this number increased to 1000 by Kepler in 1627 when he published his "Rudolphine Tables." The second volume, which had been privately printed in Uraniborg in 1588 with the title De Mundi aertherii recentioribus phaenomenis, was mainly cocerned wiyh the comet of 1577 which, Tycho showed, as he had the new star, possessed no appreciable paeallax and was therefore an extra-terrestrial phenomenon. This volume also includes an account of the Tychonic system in which a middle ground was sought between the Ptolemaic and Coprnican systems. The immobility of the Earth was retained from the Ptolemaic systems but the other planets were made to revolve around the Sun, which, with this planets, annually circuited the Earth. In both the Tychonic and Ptolemaic systems, the sphere of the fixed stars performed a diurnal rotation. Tycho, in correspondence, tried to convert Galileo from the Coprrnican systems on the basis of the fact that his precise observations showed no sensibale relative motion of the fixed stars, but Galileo was unconvinced and groups Tycho with Aristotle and Ptolemy in his Diologue on the Two Systems of the World, although he expresses admiration for Tycho's observational results.
In Astrnomiae instauratae Mechanica, Tycho published at Wandbeck, in 1598, a description of his instruments, together with an autobiographical account of his career and discoveries, including the outstanding one of a new variation in the motion of the Moon. His Epistolae Astronomicae, printed at Uraniborg in 1596, where embodied in a complete edition of his works issued at Frankfurt in 1648. He was the first to allow for the effect of refraction, by the Earth's atmosphere, on astronomical observations and introduced methods for the correction of instrumental errors and the averaging of accedental errors. He substantially corrected the received value of nearly every astronomical quantity and his observations on Hven are characterized by their accuracy and their continuity.
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