Half of the major axis is termed a semi-major axis. The equation for Kepler’s Third Law is P² = a³, so the period of a planet’s orbit (P) squared is equal to the size semi-major axis of the ...

Kepler’s second law says that a line joining a planet and ... and the orbit’s semi-major axis in astronomical units, the equation simplifies to period squared equals semi-major axis cubed.

Johannes Kepler was a 16th century astronomer who established three laws which govern the motion of planets around the sun. These are known as Kepler’s laws of planetary motion. These laws ...

(These are usually presented as "Kepler's three laws of planetary motion," but taking ... period and orbital distance gives a "1 = 1" equation for Earth. It takes Earth one year to orbit the ...