Johannes+Kepler

Johannes Kepler Born 1571, Died 1630. He was a german who went to Prague to become Brahe's assisitant. Kepler and Brahe didn't get along very well. Brahe thought that Kepler take over his glory. So he therefor let Kepler see only part of his voluminous data. Unlike Brahe, Kepler believed in the Copernican system.



Kepler's three laws of planetary motion: 1. The orbits of the planets are elipses, with the sun at one focus of the elipse. 2. The line joining the planet to the sun sweeps out equal areas in equal times as the planet travels around the elipse. 3. The ratio of squares of the revolutionary periods of two planets is equal to the ratio of the cubes of their semimajor axes.

http://csep10.phys.utk.edu/astr161/lect/history/kepler.html