1. The orbits of the planets are ellipses with the sun at one focus.

2. A line from the planet to the sun sweeps over equal areas in equal intervals of time. This is equivalent to the statement of conservation of angular momentum.

3. , where T is the orbital period in years and a is the semimajor axis in AU. Also known as the harmonic law.

Kepler's First Law, Kepler's Second Law, Kepler's Third Law