Tycho Brahe

Tycho Brahe was a Danish astronomer who produced the most accurate and comprehensive naked-eye astronomical observations made up to that point in history, working in the decades before the telescope came into astronomical use. In 1572 he observed a new, previously unrecorded star, now understood to have been a supernova, and his careful measurements showed it did not move relative to the other fixed stars the way a nearby object would, evidence that challenged the prevailing Aristotelian belief that the heavens beyond the Moon were permanent and unchanging. With generous funding from the Danish crown, Brahe built the observatory complex of Uraniborg on the island of Hven, where he and his assistants compiled an unusually precise, decades-long record of planetary and stellar positions using large purpose-built instruments. Late in his life Brahe took on Johannes Kepler as an assistant, and after Brahe's death in 1601, Kepler used this same body of observational data to derive his three laws of planetary motion, making Brahe's meticulous measurements the essential empirical foundation for one of the major breakthroughs of the scientific revolution.