|astronomy one of five points in the plane of revolution of two bodies in orbit around their common centre of gravity, at which a third body of negligible mass can remain in equilibrium with respect to the other two bodies|
|Lagrangian point (lə-grān'jē-ən) Pronunciation Key
A point in space where a small body with negligible mass under the gravitational influence of two large bodies will remain at rest relative to the larger ones. In a system consisting of two large bodies (such as the Sun-Earth system or the Moon-Earth system), there are five Lagrangian points (L1 through L5). Knowledge of these points is useful in deciding where to position orbiting bodies.