Rhea (moon)

moon of Saturn

Rhea (/ˈrə/;[a] Ancient Greek: Ῥέᾱ) is Saturn's second largest moon. It is made of ice and rock.

PIA07763 Rhea full globe5.jpg
Cassini view of Rhea's anti-Saturnian hemisphere, showing the moon's two largest impact basins (Mamaldi above and left of center, and adjacent Tirawa to its upper right). At highest resolution, several long linear features are visible: halfway down from center is Harahvaiti Fossa, while near the limb left of the bottom is Koykamou Catena.
Discovered byG. D. Cassini
Discovery dateDecember 23, 1672
Saturn V
Orbital characteristics[1]
527 108 km
Eccentricity0.001 258 3
4.518 212 d
Inclination0.345° (to Saturn's equator)
Satellite ofSaturn
Physical characteristics
Dimensions1532.4×1525.6×1524.4 km 
Mean radius
763.8 ± 1.0 km 
7 337 000 km²
Mass(2.306 518 ± 0.000 353)×1021 kg (~3.9×104 Earths)
Mean density
1.236 ± 0.005 g/cm³
0.265 m/s²
0.635 km/s
4.518 212 d
Albedo0.949 ± 0.003 (geometric) 
Surface temp. min mean max
Kelvin 53 K   99 K
10 [2]
Photo of Rhea taken by the Cassini-Huygens probe

Ring systemEdit

Rhea may have a thin ring system with three narrow bands in a disk of solid particles. These would be the first rings seen around a moon. The discovery was announced in the journal Science on March 6, 2008.


  1. In US dictionary transcription, US dict: rē′·ə.


  1. Natural Satellites Ephemeris Service Minor Planet Center
  2. Observatorio ARVAL (April 15, 2007). "Classic Satellites of the Solar System". Observatorio ARVAL. Retrieved 2011-12-17.