Kepler’s Laws

Kepler’s Laws describe planetary motion: (1) Planets orbit the Sun in ellipses, with the Sun at one focus; (2) A line segment joining a planet and the Sun sweeps out equal areas during equal time intervals, meaning planets move faster when closer to the Sun; (3) The ratio of the cubes of the semi-major axes of two planets’ orbits is equal to the ratio of the squares of their orbital periods. These laws revolutionized our understanding of the solar system.