celestial mechanics

That discipline in physics (and astronomy) dealing with the laws that govern the motions of heavenly bodies. Originally seen as distinct from the motions of bodies on earth (see Kepler’s laws of motion), it has been a sub-discipline of mechanics ever since Newton derived the cosmic laws of motions from more general mechanical laws.

For most astronomical applications, Newtonian, classical mechanics works perfectly well, however, as soon as high-precision measurements or strong gravitational fields come into play, celestial mechanics is governed by laws of relativistic mechanics derived from Einstein’s theory of general relativity.