GAT: Kepler's laws - eMyTextBooks

GAT: Kepler's laws

Kepler's laws were discovered by the German astronomer Johannes Kepler based on his attempts to fit Tycho Brahe's observations of the orbit of the planet Mars into a circular path. At the time of Kepler's observations, both the Ptolemaic model of the universe and the Copernican model of the universe believed all heavenly bodies moved in circles, or combinations of circles.

Kepler's laws are:

1. All planets move in elliptical orbits, with the Sun as one of the two foci of the ellipse.
2. As a planet moves, it sweeps out equal areas in equal times.
3. The square of the object's period of orbit is proportional to the cube of its distance to the Sun.