Tycho Brahe

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Portrait of Brahe.

Despite his accurate observations and measurements of the positions of stars and movements of the planets, Tycho Brahe (1546-1601) could not abandon the idea of an "Earth-centered" universe. However, his two-year long observations of the color and magnitude change of a "new star" in the Constellation of Cassiopeia's helped bring the Aristotelian theory of unchanging celestial spheres to an end. His records on this new star identify it as a supernova.

Although he was the last great astronomer who rejected Copernicus' "sun-centered' theory, Brahe's "naked-eye" observations and the observation tools he designed ultimately proved helpful in developing the Gregorian calendar still in use today. Brahe's work also was useful to his assistant Kepler, who defended the Copernican sun-centered view and developed Kepler's laws.

Brahe had astronomical instruments, built in wood, brass and iron, of every known variety. His observations and measurements through these instruments changed or improved almost every single aspect of astronomical theory.