The story of how we understand planetary motion would be impossible to tell if not for the work of the German mathematician Johannes Kepler. Kepler’s Three Laws describe how the planets orbit the Sun. They describe 1 – how planets move in elliptical orbits with the Sun as the focus, 2 – a planet covers the same area of ​​space in the same amount of time, regardless of where it is in its orbit, and 3 – the period revolution is proportional to the size of its orbit.