coorbital

coorbital Describing two or more bodies, such as satellites of a planet, which share the same or a similar orbit. There are two possible circumstances in which this can happen. In one, the bodies can be separated in the same orbit by 60° of longitude, so that they never come close, as with Saturn's satellite Tethys and its two smaller coorbital satellites Calypso and Telesto. Here, the smaller satellites lie at the Lagrangian points in the orbit of Tethys. However, some coorbital bodies are in adjacent orbits with marginally different periods and hence can pass each other. This happens with Saturn's satellites Janus and Epimetheus, whose orbits are just 50 km apart. These two satellites actually swap orbits when the inner satellite, moving faster than the outer one, overtakes the outer one and changes places with it.