Orbital resonance occurs when two orbiting bodies have period of revolution that are in a simple integer ratio, so that they exert a regular gravitational influence on each other. This may serve to destabilize one of the orbits. For instance, there are a serious of lanes in the [asteroid belt]
? called [Kirkwood gaps]
? where the asteroids would be in resonance with
Jupiter. Alternatively, it may serve to stabilize the orbits and protect them from gravitational perturbations. For instance
Pluto and some smaller bodies called
Plutinos were saved from ejection by a 3:2 resonance with
Neptune and the
Trojan asteroids may be regarded as being protected by a 1:1 resonance with
Jupiter.