State Kepler's three laws.

Explanation

(i) Law of orbits : Each planet moves around the Sun in an elliptical orbit with the Sun at one of the foci.
(ii) Law of area : The radial vector (line joining the Sun to a planet) sweeps equal areas in equal intervals of time.
(iii) Law of period : The square of the time period of revolution of a planet around the Sun in its elliptical orbit is directly proportional to the cube of the semi-major axis of the ellipse.