What is another name for Kepler's third law?

Kepler's First Law, also known as The Law of Ellipses — The orbits of the planets are ellipses, with the sun at one focus. ... Kepler's Third Law, or The Law of Harmony — The time required for a planet to orbit the sun, called its period, is proportional to half the long axis of the ellipse raised to the 3/2 power.