Planetary ring
A planetary ring is a ring made of dust and other particles orbiting around a planet in a flat-disc shaped region. The gas giants Jupiter, Saturn, Uranus and Neptune are the only planets known to have rings, with the rings of Saturn being the most spectacular system of rings.
The rings sometimes have "shepherd satellites". These moons orbit either in between ring gaps or the outside edge of a ring. The moons' gravity maintain the rings current shape with a well defined edge. Any material that drifts closer to a Moon's orbit, it can either move back into the body of the ring, deflect out into space, or is added onto the Moon's surface.
The rings can be made of silica or water ice. It is not known how any of the rings were formed. They are usually inside the Roche limit where large satellites cannot form.
+{{{1}}}−{{{2}}}
Planetary Ring Media
- PIA07712 - F ring animation videoquality 6 framerate 5.ogv
The moons Prometheus (right) and Pandora (left) orbit just inside and outside, respectively, the F ring of Saturn, but only Prometheus is thought to function as a shepherd moon.
- Chariklo occultation 2017 Jul 23 Morgado et al. 2021 Fig 4.jpg
Silhouette of Chariklo and its rings on 23 July 2017, revealed by occultation observations from various locations on Earth
- Haumea with rings (37641832331).jpg
Artist's depiction of Haumea's ring system
- Quaoar-Weywot orbit diagram projected.png
A diagram of Quaoar, its moon Weywot, and its two known rings.
Ring formation around extrasolar planet
