Rings of Rhea

Rhea, the second-largest moon of Saturn, may have a tenuous ring system consisting of three narrow, relatively dense bands within a particulate disk.

[3] According to the discovery team, the pattern of depletion is best explained by assuming the electrons are absorbed by solid material in the form of an equatorial disk of particles perhaps several decimeters to approximately a meter in diameter and that contains several denser rings or arcs.

[5][6] However, an equatorial chain of bluish marks on the Rhean surface suggests past impacts of deorbiting ring material and leaves the question unresolved.

It passed within 500 km of Rhea's surface, downstream of Saturn's magnetic field, and observed the resulting plasma wake as it had with other moons, such as Dione and Tethys.

In addition, the Magnetospheric Imaging Instrument (MIMI) observed that this gentle gradient was punctuated by three sharp drops in plasma flow on each side of the moon, a pattern that was also nearly symmetrical.

Two years later, in October 2009, it was announced that a set of small ultraviolet-bright spots distributed in a line that extends three quarters of the way around Rhea's circumference, within 2 degrees of the equator, may represent further evidence for a ring.

The obvious candidates for magnetospheric plasma-absorbing matter are neutral gas and dust, but the quantities required to explain the observed depletion are far greater than Cassini's measurements allow.

"[2]The simplest explanation for the symmetrical punctuations in plasma flow are "extended arcs or rings of material" orbiting Rhea in its equatorial plane.

An artist's impression of Rhea's rings. The density of the particles is exaggerated greatly to aid visibility. [ 1 ]
Comparison of Magnetospheric Imaging Instrument (MIMI) readings at Rhea and Tethys, marking possible rings. Magnetic interference is more turbulent at Rhea than at Tethys, so its shadow is not as clear-cut.
A 100 s exposure of a back-lit Rhea failed to find any evidence of rings, whether they are too tenuous or do not scatter enough light to be detected. This viewing geometry is attuned to detecting dust-sized particles, so a ring made of larger debris is possible. The sun-lit crescent is on the lower side; the gibbous illumination on the left is planetshine .
The fresh ice (dark) can be seen spanning the equator in this image comparing infrared and green wavelengths.
Fresh blue ice at Rhea's equator suggest impacts from deorbiting ring material.
The Sun, the planets, their moons, and several trans-Neptunian objects The Sun Mercury Venus The Moon Earth Mars Phobos and Deimos Ceres The main asteroid belt Jupiter Moons of Jupiter Rings of Jupiter Saturn Moons of Saturn Rings of Saturn Uranus Moons of Uranus Rings of Uranus Neptune Moons of Neptune Rings of Neptune Pluto Moons of Pluto Haumea Moons of Haumea Makemake S/2015 (136472) 1 The Kuiper Belt Eris Dysnomia The Scattered Disc The Hills Cloud The Oort Cloud