You're looking for Kepler's third law, which is a result of inverse square law and Newton's laws: https://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_mo

You're looking for Kepler's third law, which is a result of inverse square law and Newton's laws: https://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_motion#Third_law_of_Kepler https://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_m... For all planets, the ratio of the (cubed) distance from the sun to (squared) period is a constant which only depends on the mass of the sun, regardless of the mass of the planets (all assuming that the sun is far massive than any other planet.)