Jupiter Several of
Jupiter's small innermost moons, namely
Metis and
Adrastea, are within Jupiter's
ring system and are also within Jupiter's
Roche limit. It is possible that these rings are composed of material that is being pulled off these two bodies by Jupiter's
tidal forces, possibly facilitated by impacts of ring material on their surfaces.
Saturn The complex
ring system of Saturn has several such satellites. These include
Prometheus (F ring),
Daphnis (Keeler Gap),
Pan (Encke Gap),
Janus, and
Epimetheus (both A ring).
Uranus Uranus also has shepherd moons on its
ε ring,
Cordelia and
Ophelia. They are interior and exterior shepherds, respectively. Both moons are well within Uranus's synchronous orbit radius, and their orbits are therefore slowly decaying due to
tidal deceleration.
Neptune Neptune's rings are very unusual in that they first appeared to be composed of incomplete arcs in Earth-based observations, but
Voyager 2's images showed them to be complete rings with bright clumps. It is thought that the gravitational influence of the shepherd moon
Galatea and possibly other as-yet undiscovered shepherd moons are responsible for this clumpiness.
Minor planets Rings around some
centaurs have been identified.
Chariklo's rings are remarkably well-defined and are suspected to either be very young or kept in place by a shepherd moon similar in mass to the rings.
Chiron is also thought to have rings similar in form to those of Chariklo.
Exoplanets A major gap in the
circumstellar disk or large ring system of the free-floating
brown dwarf or
rogue planet J1407b at about 61 million km (0.4
AU) from its center is considered to be indirect evidence of the existence of an
exomoon (or
exoplanet) with mass up to 0.8
Earth masses. == See also ==