Chapter 12 Gravitation
Newton discovered the law of gravitation through his studies of planetary motion. At the time of Newton, planetary motion was understood in terms of Kepler's three laws, which were based on the astronomical observations of Tycho Brahe. Newton was able to explain the origin of Kepler's laws from a more fundamental perspective by solving the equation of motion subject to a gravitational force given by his law of gravitation. Newton's successful explanation of the planetary laws of Kepler was a major achievement and led to the acceptance of his laws of mechanics and ushered in the new era of physics.