Lagrange point



In celestial mechanics, the Lagrangian points (lso Lagrange points, L-points, or libration points) are positions in an orbital configuration of two large bodies where a small object affected only by gravity can maintain a stable position relative to the two large bodies. The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to orbit with them. There are five such points, labeled L1 to L5, all in the orbital plane of the two large bodies. The first three are on the line connecting the two large bodies and the last two, L4 and L5, each form an equilateral triangle with the two large bodies. The two latter points are stable, which implies that objects can orbit around them in a rotating coordinate system tied to the two large bodies.

Many planets have minor planets near their L4 and L5 points (trojans) with respect to their Sun, with gas giants in particular having more than a million of these. Artificial satellites placed at L1 and L2, and the Lagrangian points are used for a variety of purposes.

