(n) a law concerning the speed at which planets travel; a line connecting a planet to the sun will sweep out equal areas in equal times, Syn. law of equal areas, law of areas, Example:Kepler's second law means that a planet's orbital speed changes with its distance from the sun
(n) 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, Syn. harmonic law