Tyge (Latinized as Tycho) Ottesen Brahe was born on 14 December 1546 in Knudstrup, a town in the Scania region of southern Sweden (then controlled by Denmark). At an early age he was taken into the care of his paternal uncle, who raised Tycho and provided liberally for his education.
From the age of six until he was twelve years old Tycho took a Latin School education. In 1559 Tycho began to study law at the University of Copenhagen (est.1479). The following year on 21 August he observed a partial eclipse of the Sun and this so impressed him that, particularly as it had been predicted, he began to study astronomy. In 1562 he set off for the University of Leipzig (est.1409) to continue his studies of law. When he was seventeen he recorded a conjunction of Jupiter and Saturn on 17 August 1563 and found that the Alfonsine Tables were off by a month and even the Prutenic Tables (1551) by Erasmus Reinhold (1511-53), sponsored by the Duke of Prussia Albert Frederick (65; r.1568-1618) and based on Copernicus models, were nearly two days wrong.
Between 1566 and 1570 he studied astronomy in Rostock, Wittenberg and Basel. Tycho had been working on improved instruments for observing for a while and at Augsburg he built a large wooden quadrant with a 19-foot (≈5.8-metre) radius, graduated in sixtieths of a degree; it was the beginning of his accurate observations.
Receiving word that his father was ill, Tycho returned home during the last few days of 1570. His father died in 1571 and soon after, with the help of his other uncle, Tycho began constructing an observatory at the Herrevad Abbey. On 11 November 1572 Tycho observed a star-like object bright enough to be seen in the daytime that appeared in the constellation of Cassiopeia and remained visible for eighteen months.
Aristotelians believed that the Universe beyond the Moon was eternally unchangeable and many observers of the phenomenon held that it was in the terrestrial sphere below the Moon. Tycho, however, found that, unlike the planets, the object did not change its position relative to the fixed stars. This suggested it was not a planet, but a fixed star in the stellar sphere beyond all the planets. (We now know that the star was a supernova 8000 light years from Earth.) In 1573 he published a small book, De nova stella (‘On the New Star’).
In 1576 the king of Denmark and Norway Frederick II (53; r.1559-88), impressed with Tycho’s 1572 observations, financed the construction of an observatory Uraniborg (‘Heavenly Castle’) on the island of Hven. In c.1584 Tycho built Stjerneborg (‘Castle of the Stars’), a largely underground observatory adjacent to Uraniborg.
In November 1577 a brilliant comet appeared. Aristotle had taught that comets were atmospheric phenomena but Tycho’s observations revealed no measurable parallax. This implied that the comet was located beyond the sphere of the Moon.
From its brightening and dimming and displacement with respect to the background stars, Tycho calculated that the comet had passed through several of the concentric celestial spheres on which the planets were supposed to be carried. This implied that the spheres did not exist at all.
Tycho’s report in 1572 had had little reaction. This time he presented a comprehensive analysis of his observations together with critique of the results of other observers. When his book De Mundi Aetherei Recentioribus Phaenomenis Liber Secundus finally appeared in 1588, the transfer of comets from meteorology to astronomy was assured.
Tycho could not accept the Copernican system. Even with his superb instrumentation Tycho could not detect the annual movement of the stars that was to be expected if they were being observed from a moving Earth. Either Copernicus was wrong and Earth was at rest, or the stars were so far away that their apparent movements were too small to be detected. For Tycho such a large Universe was not comprehendible.
In 1583 Tycho put forward his scheme for the structure of the Solar System. In his Tychonic System, which soon replaced the Ptolemaic as the most popular of Earth-centred models, the Moon and the Sun orbit Earth; the other five planets orbit the Sun and are carried with the Sun around Earth; and the stars are in a thin shell of space centred on Earth and positioned just beyond the furthest position reached by any planet. Following a disagreement with Frederick II’s son Christian IV (70; r.1588-1648) Tycho left Hven in 1597. He eventually moved to Prague and took service with Emperor Rudolf (59; Holy Roman Emperor 1576-1612). In 1601 Tycho secured a commission for Johannes Kepler to collaborate with him on a new project: the Rudolphine Tables to replace the Prutenic Tables. Tycho fell ill a few weeks later and died the following day on 24 October 1601.
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