Tycho Brahe

Tycho Brahe was a Danish nobleman whose passion for precise astronomical measurement transformed the science. After observing the supernova of 1572 (now called "Tycho's supernova"), which proved that the heavens were not immutable as Aristotle had taught, he received the island of Hven from King Frederick II and built Uraniborg, the most advanced astronomical observatory of the pre-telescopic era. Over two decades, Tycho amassed the most precise body of astronomical observations ever collected, with positional accuracy of about one arcminute — a feat not surpassed until the invention of the telescope. His meticulous observations of Mars became the foundation for Kepler's discovery of elliptical orbits. Tycho proposed his own compromise model of the solar system (the Tychonic system) in which the planets orbited the Sun, but the Sun orbited a stationary Earth.

Observed and documented the supernova of 1572 (SN 1572), proving that the celestial sphere could change. Built Uraniborg observatory and achieved ~1 arcminute positional accuracy without a telescope. Compiled the most comprehensive and accurate pre-telescopic star catalog. His Mars observations enabled Kepler to discover elliptical orbits. Observed the Great Comet of 1577, proving comets were beyond the Moon.