Ellipses became important in [[astronomy]] in the early 1600s, when [[Kepler]] proved that planets orbiting the sun always follow elliptical paths. This helped overturn the [[Ptolemaic theory]], and led to [[Issac Newton]]'s [[law of gravitation]]. | Ellipses became important in [[astronomy]] in the early 1600s, when [[Kepler]] proved that planets orbiting the sun always follow elliptical paths. This helped overturn the [[Ptolemaic theory]], and led to [[Issac Newton]]'s [[law of gravitation]]. |