Kepler's laws are the laws of planetary motion discovered by Kepler. In 1609 he published two laws of planetary motion in his New Astronomy, and in 1618 he discovered a third law. Kepler was lucky enough to have access to the famous Danish astronomer Tycho Brahe<br><br>Very accurate astronomical data, observed and collected. Around 1605, based on Brahe's data on the positions of the planets, Kepler discovered that planets move according to three fairly simple laws. Kepler's laws challenged the Aristotelians and Ptolemies in astronomy and physics. He argued that the earth was constantly moving; The orbits of the planets are not epicycle, but elliptical; The planets orbit at unequal speeds. These arguments greatly shook up astronomy and physics at the time. After almost a century of painstaking research, physicists have finally been able to explain this with physical theory. Newton used his second law and the law of gravitation to prove Kepler's law mathematically and to make its physical implications known.