Editing Celestial mechanics (section)

===Newtonian mechanics and universal gravitation===
[[Isaac Newton]] is credited with introducing the idea that the motion of objects in the heavens, such as [[planet]]s, the [[Sun]], and the [[Moon]], and the motion of objects on the ground, like [[cannon]] balls and falling apples, could be described by the same set of [[physical law]]s. In this sense he unified ''celestial'' and ''terrestrial'' dynamics. Using [[Newton's law of universal gravitation|his law of gravity]], Newton confirmed [[Kepler's laws of planetary motion|Kepler's laws]] for elliptical orbits by deriving them from the gravitational [[two-body problem]], which Newton included in his epochal ''[[Philosophiæ Naturalis Principia Mathematica]]'' in 1687.