Kepler's first law of planetary motion states that every planet’s orbit is elliptical and has the Sun at a focus
Kepler's second law of planetary motion states that the line joining the Sun and a planet sweeps out equal areas in equal times
Kepler's third law of planetary motion states that the square of a planet’s orbital period is proportional to the cube of the semi-major axis of its orbit
Tycho Brahe provided some accurate astronomical data which makes it possible for Kepler to develop the laws of planetary motion. He devised the best instruments available before the invention of the telescope. These data and instrument provided by Tycho Brahe was able to assist Kepler in formulating these laws
