State Kepler's three laws.

Explanation

1. Law of orbits :
Each planet moves around the Sun in an elloptical orbit with the Sun at one of the foci.
2. Law of area:
The radial vecotr (line joining the Sun to a planet) sweeps equal areas in equal intervals of time.
3. Law of period:
3. Lawo 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.