Li·bra·tion point n. any one of five points in the plane of a system of two large astronomical bodies orbiting each other, as the Earth-moon system, where the gravitational pull of the two bodies on an object are approximately equal, and in opposite directions.  A solid object moving in the same velocity and direction as such a libration point will remain in gravitational equilibrium with the two bodies of the system and not fall toward either body.

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