Knowing then that the orbits of the planets are elliptical, johannes Kepler formulated three laws of planetary motion, which accurately described the motion of comets as well.
Kepler's Laws of Planetary Motion
Kepler's three laws describe how planetary bodies orbit the Sun. They describe how
1) Planets move in elliptical orbits with the Sun as a focus
2) A planet covers the same area of space in the same amount of time no matter where it is in its orbit
3) A planet’s orbital period is proportional to the size of its orbit (its semi-major axis).