1546-1601. With his discovery of "the new star" in 1572, Tycho Brahe became famous as an astronomer throughout Europe.
To secure him for Denmark, Frederik II endowed him in 1576 with the island of Ven, where he gradually built up a research institution of an entirely new kind. This comprised the extensive castle of Uranienborg, the observatory of Stjerneborg, a paper mill and printing press, and a workshop for making instruments, by means of which Tycho Brahe gradually increased the accuracy of his observations to the limits of what the naked eye could see.
He rejected all previous observations as dubious, and aimed to "reconstruct astronomy" by personally surveying all heavenly phenomena from scratch. This work continued until 1597, when after a quarrel with Christian IV Tycho Brahe left Denmark. He took all his equipment with him and ended his days as a "mathematician" at the court of the Emperor Rudolph II of Vienna.
Among Tycho Brahe's many results was the demonstration in 1577 that a comet was a heavenly body and not an atmospheric phenomenon as previously assumed. In addition came the discovery of two hitherto unknown "anomalies" in the movements of the moon and a catalogue containing the positions of 1000 fixed stars.
He himself did not manage to utilize his many planetary observations, but in 1600 he handed a series of observations of Mars to Johannes Kepler, who used them in deriving his three fundamental laws for the movement of the planets in general.
Tycho Brahe's cosmology with the Earth at the centre of a system, circled by the Sun, around which the other planets rotate, was widely used in the 17th century as an alternative to the Copernican system condemned by the Church.
Olaf Pedersen, Gyldendal Leksikon