Co-orbital configuration
In astronomy, a co-orbital configuration is a configuration of two or more astronomical objects (such as asteroids, moons, or planets) orbiting at the same, or very similar, distance from their primary; i.e., they are in a 1:1 mean-motion resonance. (Or 1:−1 if orbiting in opposite directions.) There are several classes of co-orbital objects, depending on their point of libration.