Lagrange Points

pbholmes · Lagrange Points

When two relatively heavy objects orbit one another, there are five special points where a third, light, object can be locked into a stable relationship with the other two.

Some Lagrange points, such as the Sun-Jupiter ones have asteroids sitting in them, and the Earth-Moon ones have dust clouds. Other Lagrange points don't seem to have anything much.

For more details, see this fascinating article: http://math.ucr.edu/home/baez/lagrange.html.