Quadrant of Tycho Brahe, 16th century

Quadrant of Tycho Brahe, 16th century. Heliotype photograph from 1876-1900. Tycho Brahe (1546-1601) was born on 14 December 1546 in Skane, then in Denmark, now in Sweden. Brahe's contributions to astronomy were enormous. He not only designed and built instruments, but calibrated them. Earlier astronomers had been content to observe the positions of planets and the Moon at certain important points of their orbits. Brahe and his assistants observed these bodies throughout their orbits. His observations, set out in his publications on these phenomena, were instrumental in establishing the fact that these bodies were above the Moon and that therefore the heavens were not immutable as Aristotle had argued and philosophers still believed. ©SSPL/Science Museum