Kepler's law of planetary motion

law of nature, law - a generalization that describes recurring facts or events in nature; "the laws of thermodynamics"

Kepler's first law - a law stating that the orbit of each planet is an ellipse with the sun at one focus of the ellipse

Kepler's second law, law of areas, law of equal areas - 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; "Kepler's second law means that a planet's orbital speed changes with its distance from the sun"

harmonic law, 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

astronomy, uranology - the branch of physics that studies celestial bodies and the universe as a whole