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  • Print publication year: 2019
  • Online publication date: March 2019

6 - Instruments of reform: Tycho’s restoration of observational


While the Copernican theory was endorsed by some writers such as Thomas Digges and Giordano Bruno, most astronomers remained skeptical of a moving Earth. One such skeptic was Tycho Brahe, who set out to reform astronomy through improved observational methods. His careful observations of a new star (or “nova”) and a comet indicated that change could occur in the heavens, in contrast to the teachings of Aristotle. However, his observations of the angular size of stars seemed to contradict Copernicus’ theory. Tycho proposed a new geoheliocentric model in which the Earth sits at rest at the center of the cosmos and the Sun orbits around the Earth, but the planets orbit around the Sun. This model retained the stationary Earth but included some of the best features of the Copernican model. In an attempt to find evidence for his model, Tycho made extraordinarily extensive and accurate measurements of planetary positions, particular of the planet Mars.