# Kepler's third law

> physical law that the square of a planet’s orbital period is proportional to the cube of the orbit’s semimajor axis

**Wikidata**: [Q122928319](https://www.wikidata.org/wiki/Q122928319)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Kepler's_third_law)  
**Source**: https://4ort.xyz/entity/kepler-s-third-law