Kepler's Laws

An Introduction To Kepler's Laws
Kepler's Laws, as they known collectively, are three laws that govern planetary motion. They were named after Dr. John Kepler, a "german astrologer and astromer", circa 1610.

Kepler's First Law of Orbits
Kepler's Law of Orbits states that "[e]very planet moves in an ellipse".

Kepler's Second Law of Areas
Kepler's Law of Areas states that "[t]he radius vector drawn from the sun to the planet sweeps out inequal areas in equal times". This Law "arises from the conservation of angular momentum."

Kepler's Third Law of Periods
Kepler's Law of Periods states that "[t]he squares of the times taken to describe their orbits by two planetsare proportional to the cubes of the major semi axes of the orbits."