Orbital resonanceOrbital resonance
occurs when two orbiting bodies have periods 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 is a series 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.
A Laplace resonance occurs when more than two orbiting bodies have a simple integer ratio between their orbital periods. For example, Jupiter's moons Ganymede, Europa, and Io are in a 1:2:4 orbital resonance.
See also Tidal locking.