Saturn's Moon: Hyperion Rotation

Hyperion (pronounced /haɪˈpɪəriən/, or as in Greek Ὑπερίων), also known as Saturn VII, is a moon of Saturn discovered by William Cranch Bond, George Phillips Bond and William Lassell in 1848. It is distinguished by its irregular shape, its chaotic rotation, and its unexplained sponge-like appearance.
The moon is named after Hyperion, a Titan in Greek mythology. It is also designated Saturn VII. The adjectival form of the name is Hyperionian.
Hyperion's discovery came shortly after John Herschel had suggested names for the seven previously-known satellites of Saturn in his 1847 publication Results of Astronomical Observations made at the Cape of Good Hope. William Lassell, who saw Hyperion two days after William Bond, had already endorsed Herschel's naming scheme and suggested the name Hyperion in accordance with it. He also beat Bond to publication.
Hyperion is one of the largest highly irregular (non-spherical) bodies in the solar system (second to Proteus). The largest crater on Hyperion is approximately 121.57 km in diameter and 10.2 km deep. A possible explanation for the irregular morphology is that Hyperion is a fragment of a larger body that was broken by a large impact in the distant past. Like most of Saturn's moons, Hyperion's low density indicates that it is composed largely of water ice with only a small amount of rock. It is thought that Hyperion may be similar to a loosely accreted pile of rubble in its physical composition. However, unlike most of Saturn's moons, Hyperion has a low albedo (0.20.3), indicating that it is covered by at least a thin layer of dark material. This may be material from Phoebe (which is much darker) that got past Iapetus. Hyperion is redder than Phoebe and closely matches the color of the dark material on Iapetus.
Hyperion has a porosity of about 0.46.

Discovered by William Bond, George Bond, William Lassell
Discovery date 16 September 1848
Designations
Alternate name Saturn VII
Adjective Hyperionian
Orbital characteristics
Semi-major axis 1,481,009 km
Eccentricity 0.1230061
Orbital period 21.276 d
Inclination 0.43° (to Saturn's equator)
Satellite of Saturn
Physical characteristics
Dimensions 328 km × 260 km × 214 km
(geometric mean 263 km)
Mean radius 135.00±4.00 km
Mass 0.5584±0.0068×1019 kg
Mean density 0.5667±0.1025 g/cm3
Equatorial surface gravity 0.0170.021 m/s2 depending on location[8]
Escape velocity 4599 m/s depending on location .
Rotation period chaotic
Axial tilt variable
Albedo 0.3
Apparent magnitude 14.1

Category:

Science & Technology

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• Saturn moon Hyperion
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