Brahe, Tycho (15461601), a Danish astronomer. Tycho achieved fame by writing a book on the brilliant new star that appeared in 1572. (Actually, it was a supernova, an old star that suddenly becomes extremely bright.) His observations of this star (later named Tycho's Star in his honor), made over a period of 18 months, disproved the notion then held that the heavens never change.

Tycho's interest in astronomy was stirred by witnessing a partial eclipse of the sun in 1560. His family, of the Danish nobility, felt disgraced that he chose to become an astronomer rather than study law. In 1576 he received the patronage of his king, Frederick II, and was thus enabled to build the finest observatory in the world, Uraniborg. The observations he made there are considered the most accurate ever made before the invention of the telescope. Tycho left Denmark for Germany in 1597, and moved to Prague in 1599 to serve as imperial mathematician of Holy Roman Emperor Rudolph II. Tycho's most famous assistant was Johannes Kepler, who joined him in 1600.