The planets rotate around the sun in elliptical orbits such that 1. The orbit of a planet is an ellipse with the Sun at one of the two foci. 2. A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time. 3. The square of a planet's orbital period is proportional to the cube of the length of the semi-major axis of its orbit.
| 1514 AD | Copernicus | Heliocentric theory |
| 1609 AD | Kepler | Laws of planetary motion |
| 1684 AD | Newton | Theory of gravitation |