Definition that contains astronomical unit
- kepler's third law a law stating that the ratio of the square of the revolutionary period (in years) to the cube of the orbital axis (in astronomical units) is the same for all planets
- solar parallax the angle subtended by the mean equatorial radius of the Earth at a distance of one astronomical unit
- harmonic law a law stating that the ratio of the square of the revolutionary period (in years) to the cube of the orbital axis (in astronomical units) is the same for all planets