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Rhea (moon)
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 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. | |||||||||
| Discovery | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Discovered by | G. D. Cassini | ||||||||
| Discovery time | December 23, 1672 | ||||||||
| Names | |||||||||
| Other names | Saturn V | ||||||||
| Adjective | Rhean | ||||||||
| Orbit [1] | |||||||||
| Longest distance from the center of its orbital path ("semi-major axis") |
527 108 km | ||||||||
| How egg-shaped its orbit is ("eccentricity") |
0.001 258 3 | ||||||||
| How long it takes to complete an orbit | 4.518 212 d | ||||||||
| Angle above the reference plane ("inclination") |
0.345° (to Saturn's equator) | ||||||||
| What it orbits | Saturn | ||||||||
| Size and Other Qualities | |||||||||
| Measures | 1532.4×1525.6×1524.4 km | ||||||||
| Average distance from its center to its surface | 763.8 ± 1.0 km | ||||||||
| Area of its surface | 7 337 000 km² | ||||||||
| Mass | (2.306 518 ± 0.000 353)×1021 kg (~3.9×10−4 Earths) | ||||||||
| Average density | 1.236 ± 0.005 g/cm³ | ||||||||
| Gravity at its surface | 0.265 m/s² | ||||||||
| Slowest speed able to escape into space ("escape velocity") |
0.635 km/s | ||||||||
| How long it takes to turn around one time |
4.518 212 d (synchronous) | ||||||||
| Angle at which it turns (in relation to its orbit) |
zero | ||||||||
| How much light it reflects | 0.949 ± 0.003 (geometric) | ||||||||
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| Seeming brightness ("apparent magnitude") |
10 [2] | ||||||||
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Rhea (/ˈriːə/;[a] Ancient Greek: Ῥέᾱ) is Saturn's second largest moon. It is made of ice and rock.
Ring system
Main page: Rings of Rhea
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.
Notes
References
- ↑ Natural Satellites Ephemeris Service Minor Planet Center
- ↑ Observatorio ARVAL (April 15, 2007). "Classic Satellites of the Solar System". Observatorio ARVAL. http://www.oarval.org/ClasSaten.htm. Retrieved 2011-12-17.
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