Laws of planety motion
There are three main laws; 1) The orbit of a planet has these ellipses with the Sun at one of the two foci, 2) A line segment joining a planet and the sun sweeps out equal areas during equal intervals of time, 3) The square of the orbital period of proportional to the cube of the cube of the semi-major axis of its orbit. Basically the process of how the planets rotate around the sun. The laws describe how the cycles form ellipses rather than circles. Every planet has these ellipses with their sun.