Samuel Chiltern answered
Although you haven't specified, I think it's safe to assume that you are specifically referring to planets within our solar system, and not the wider universe.
None of the inner planets in the solar system (Mercury, Venus, Earth and Mars) have rings surrounding them - and only two of these planets (Earth and Mars) have moons.
These small planets possess relatively little orbitary matter in general, compared with the vast outer planets.
However, all of the outer planets (commonly referred to as 'gas giants') possess rings, some of which are far more faint than others. All these planets possess many moons, and more are still being discovered.
The Outer Planets, and Their Planetary Rings
Technically referred to as planetary rings, the rings surrounding the outer planets are composed of cosmic dust, ice and rock. They orbit their parent planet to form a flat, disc-shaped ring.
Saturn has the most distinct rings, and some of its many moons act to 'shepherd' this disc of matter, keeping it in line. The moons help to maintain the sharp, defined edges of Saturn's rings, since their gravity either flings straying material back into the ring, or pulls it into the moon itself.
Neptune's rings, are far less pronounced than Saturn's, but are still quite interesting, since they originally appeared to be incomplete. However, observations made from outside the Earth's atmosphere show that the rings have a mixture of bright and dull spots - and the bright spots in Neptune's rings make them appear to have missing parts.
It is thought that this phneomenon may be explained by the influence of one or more as-yet-undiscovered moons.
None of the inner planets in the solar system (Mercury, Venus, Earth and Mars) have rings surrounding them - and only two of these planets (Earth and Mars) have moons.
These small planets possess relatively little orbitary matter in general, compared with the vast outer planets.
However, all of the outer planets (commonly referred to as 'gas giants') possess rings, some of which are far more faint than others. All these planets possess many moons, and more are still being discovered.
The Outer Planets, and Their Planetary Rings
Technically referred to as planetary rings, the rings surrounding the outer planets are composed of cosmic dust, ice and rock. They orbit their parent planet to form a flat, disc-shaped ring.
Saturn has the most distinct rings, and some of its many moons act to 'shepherd' this disc of matter, keeping it in line. The moons help to maintain the sharp, defined edges of Saturn's rings, since their gravity either flings straying material back into the ring, or pulls it into the moon itself.
Neptune's rings, are far less pronounced than Saturn's, but are still quite interesting, since they originally appeared to be incomplete. However, observations made from outside the Earth's atmosphere show that the rings have a mixture of bright and dull spots - and the bright spots in Neptune's rings make them appear to have missing parts.
It is thought that this phneomenon may be explained by the influence of one or more as-yet-undiscovered moons.
