Kepler’s first law states that: the orbits of the planets are elliptical.

the speed of a planet’s orbit varies depending on which part of the ellipse it is occupying.

the square of the ratio of the periods of any two planets revolving around the Sun is equal to the cube of the ratio of their average distance from the Sun.

objects attract other objects with a force that is directly proportional to the product of their masses, and inversely proportional to the square of the distance between them.