State Kepler's three laws.

Explanation

1. Law of the Orbits: Each planet moves around the sun in an elliptical orbit with the sun at one of the foci.
2. Law of Area : The radial vector (Line joining the sun to a planet) sweeps equal areas in equal intervala of time .
3. Law of period: The square of the time period of revolution of a planet around the sun in its elliptical orbit is directily proportional to the cube of the semi-major axis of the ellipse.
`T^(2) prop a^(3)`
`(T^(2))/(a^(3))`=Constant .