Tycho Brahe

Brahe, Tycho (1546–1601), Danish astronomer, the greatest exponent of naked-eye positional astronomy. Johannes Kepler, who became his assistant in 1601, postulated an elliptical orbit for Mars based on his confidence in Brahe's data. Brahe's “Tychonic system,” in which the planets circled the sun, which in turn orbited a stationary earth, was the principal 17th-century rival of the Copernican hypothesis. Brahe observed a supernova with the naked eye in 1872.

See also: Astronomy.