... Concerning those theories, Tycho believed that all planets revolved around the Sun, but the Sun circled Earth. ... That was when he published his first two laws of planetary motion: . ... Kepler's 3rd Law . ... Earth . ... Not only were Kepler's laws confirmed and explained by later scientists, but they apply to any orbital system of two bodies--even artificial satellites in orbit around the Earth. ... By Kepler's formula . ... More will be said about Kepler's first two laws in the next two sections...