Tycho Brahe

Tycho Brahe ran the observatory of Uraniborg on the island of Hven from 1576 for over twenty years, measuring the positions of stars and planets night after night with large instruments and a staff of assistants. Continuity and precision were the point: only a long, consistent record of Mars could show its true path. After his death his assistant Johannes Kepler used the data to find the laws of planetary motion.