__Chaos and the Solar System__

### The three-body problem

The problem of finding the general solution to the motion of more than two orbiting bodies in the solar system had eluded mathematicians since Newton's time. This was known originally as the three-body problem and later the *n*-body problem, where *n* is any number of more than two orbiting bodies. The *n*-body solution was considered very important and challenging at the close of the 19th century. Indeed in 1887, in honour of his 60th birthday, Oscar II, King of Sweden, advised by Gösta Mittag-Leffler, established a prize for anyone who could find the solution to the problem. The announcement was quite specific:

“ | Given a system of arbitrarily many mass points that attract each according to Newton's law, under the assumption that no two points ever collide, try to find a representation of the coordinates of each point as a series in a variable that is some known function of time and for all of whose values the series converges uniformly. | ” |

In case the problem could not be solved, any other important contribution to classical mechanics would then be considered to be prizeworthy. The prize was finally awarded to Poincaré, even though he did not solve the original problem. One of the judges, the distinguished Karl Weierstrass, said, *"This work cannot indeed be considered as furnishing the complete solution of the question proposed, but that it is nevertheless of such importance that its publication will inaugurate a new era in the history of celestial mechanics."* (The first version of his contribution even contained a serious error; for details see the article by Diacu^{[19]}). The version finally printed contained many important ideas which led to the theory of chaos. The problem as stated originally was finally solved by Karl F. Sundman for *n* = 3 in 1912 and was generalised to the case of *n* > 3 bodies by Qiudong Wang in the 1990s.

Read full wikipedia article at http://en.wikipedia.org/wiki/Henri_Poincar%C3%A9