Editing Orbit (section)

===Limitations of Newton's law of gravitation===
Note that while bound orbits of a point mass or a spherical body with a [[Newtonian gravitational field]] are closed [[ellipse]]s, which repeat the same path exactly and indefinitely, any non-spherical or non-Newtonian effects (such as caused by the slight oblateness of the [[Earth]], or by [[Theory of relativity|relativistic effects]], thereby changing the gravitational field's behavior with distance) will cause the orbit's shape to depart from the closed [[ellipse]]s characteristic of Newtonian [[two-body motion]]. The two-body solutions were published by Newton in [[Philosophiae Naturalis Principia Mathematica|Principia]] in 1687. In 1912, [[Karl Fritiof Sundman]] developed a converging infinite series that solves the [[three-body problem]]; however, it converges too slowly to be of much use. Except for special cases like the [[Lagrangian point]]s, no method is known to solve the equations of motion for a system with four or more bodies.