Elliptical orbits

Discovery that planetary orbits aren’t circular but elliptical. Working under Tycho Brahe, Kepler found that his teacher’s data worked best for non-circular orbits with sun at one of the foci’s. Also developed Kepler’s laws.
 Johannes Kepler Germany 1609 Elliptical orbits

Discovery that planetary orbits aren’t circular but elliptical. Working under Tycho Brahe, Kepler found that his teacher’s data worked best for non-circular orbits with sun at one of the foci’s. Also developed Kepler’s laws.