Eng: A set

一副

A set (of)

開普勒定律

A set of three scientific laws describing the motion of planets around the Sun published by Johannes Kepler (1571–1630). They define the shape of planetary orbits (1. All planets move along elliptical orbits with the Sun located at one focus.), explain how a planet's velocity changes during an orbit (2. During each orbit, a line connecting a planet with the Sun sweeps out equal areas in equal time intervals.), and relate a planet's orbital period to its distance from the Sun (3. The square of the planet's orbital period (P) is proportional to the cube of its semimajor axis).