Lagrange points are positions in space where the gravitational forces of two large masses, such as the Sun and the Earth, balance each other out. This means that a small object, such as a satellite, can orbit at these points with minimal fuel consumption. There are five Lagrange points, labeled L1 to L5, for any pair of orbiting bodies. L1, L2, and L3 are on the line connecting the centers of the two large masses, while L4 and L5 form the vertices of two equilateral triangles with the centers of the two large masses.

The Swiss mathematician Leonhard Euler identified the three collinear Lagrange points (L1, L2, L3) around 1750. This discovery preceded by about a decade the finding of the remaining two points by the Italian-born Joseph-Louis Lagrange.