Rhea

Rhea is second in size among Saturn's moons.[1] NASA reports a mean radius near 764 kilometres for Rhea.[1] JPL lists Rhea's mean radius as 763.50 kilometres.[2] Rhea keeps one hemisphere turned toward its parent planet throughout its orbit.[1]

History

The discovery of Rhea is credited to Giovanni Cassini, in 1672.[1] Both Voyager spacecraft visited Rhea during their Saturn encounters spanning 1980 and 1981.[1]

Findings

Rhea's strong reflectivity points to water ice as a major surface material.[1] The contrast between the terrain types has been interpreted as possible evidence of a large-scale resurfacing long ago.[1] Images from Cassini revealed that the wispy markings are canyon-forming fractures.[1] Cassini instruments revealed a debris disk around Rhea and evidence of a ring.[1] ESA lists Rhea's orbital period as 4.52 Earth days.[3]

Sources

  1. Rhea | NASA Science. Licence: facts-only (Track B), no text or images reused. Attribution: NASA.
  2. Planetary Satellite Physical Parameters | NASA Jet Propulsion Laboratory. Licence: facts-only (Track B), no text reused. Attribution: NASA/JPL-Caltech.
  3. Saturn's moons | ESA. Licence: facts-only (Track B), no text reused. Attribution: European Space Agency.

Evidence as of 2026-11-01.