Hyperion is the sixteenth of Saturn's known satellites:
orbit: 1,481,100 km from Saturn
diameter: 286 km (410 x 260 x 220)
mass: 1.77e19 kg
In Greek mythology Hyperion was a Titan, the son of Gaea and Uranus and the father of Helios.
Discovered by Bond and Lassell in 1848.
Hyperion is the largest highly irregular (non-spherical) body in the solar system. Proteus is quite a bit larger but is almost spherical. It seems likely 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 of water ice with only a small amount of rock.
But unlike most of Saturn's moons, Hyperion has a low albedo (.2 - .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.
The Voyager images and subsequent ground based photometry indicate that Hyperion's rotation is chaotic, i.e. its axis of rotation wobbles so much that its orientation in space is completely unpredictable. There is only one other known body in the solar system (asteroid 4179 Toutatis) that rotates chaotically but simulations seem to indicate that other irregular satellites may have done so in the past. Hyperion is unique in that it is very irregularly shaped, has a highly eccentric orbit, and is near another large moon (Titan). These factors combine to restrict the set of conditions under which stable rotation is possible. The 3:4 orbital resonance between Titan and Hyperion may also make chaotic rotation more likely.
Hyperion's odd rotation probably accounts for the fact that Hyperion's surface is more or less uniform, in contrast to many of Saturn's other moons which have distinctly different leading and trailing hemispheres.
Hyperion 是土星已知衛(wèi)星中距土星第十六近的一顆：
公轉(zhuǎn)軌道：距土星 1,481,100 千米
衛(wèi)星直徑：286 千米 (410 x 260 x 220)
質(zhì)量：1.77e19 千克
在希臘神話中，Hyperion是一個巨人，該亞與烏拉諾斯的兒子，Helios的父親。
它由波德和Lassell于1848年發(fā)現(xiàn)。
土衛(wèi)七是太陽系中的一顆高度不規(guī)則（非球形）天體。海衛(wèi)八稍大一些，但差不多是個球體?？雌饋硗列l(wèi)七像是一顆大星體的碎片，大星體因在遠(yuǎn)古時期的碰撞而碎裂。
就像土星的其他衛(wèi)星，土衛(wèi)七的低密度表明它由少量的巖石混合著冰水組成。
不像土星的其他衛(wèi)星的是，土衛(wèi)七的反照率較小(.2 - .3)，表明它至少覆蓋著一層薄薄的暗色物質(zhì)。這可能是來自遠(yuǎn)于土衛(wèi)八的更暗的土衛(wèi)九上的物質(zhì)。
旅行者號帶來的圖片與基于地的光度測定表明土衛(wèi)七的自轉(zhuǎn)混亂，比如它的自轉(zhuǎn)軸不停搖晃，在空間的方向無法確定。土衛(wèi)七是太陽系已知星體中一顆自轉(zhuǎn)混亂的星體，不過其他星體可能在遠(yuǎn)古時期也這樣。土衛(wèi)七在其他不規(guī)則外形的星體中是獨(dú)一無二的，公轉(zhuǎn)偏心率較大，與另一顆大衛(wèi)星土衛(wèi)六很近。這些因素集合在一起，限制了它穩(wěn)定自轉(zhuǎn)的條件。土衛(wèi)六與七的公轉(zhuǎn)共振比為3:4，使它自轉(zhuǎn)混亂更有可能。
土衛(wèi)七的奇怪自轉(zhuǎn)可能起因于外形的不規(guī)則，與那些具有明顯正半球與后半球的土星衛(wèi)星形成對比。
orbit: 1,481,100 km from Saturn
diameter: 286 km (410 x 260 x 220)
mass: 1.77e19 kg
In Greek mythology Hyperion was a Titan, the son of Gaea and Uranus and the father of Helios.
Discovered by Bond and Lassell in 1848.
Hyperion is the largest highly irregular (non-spherical) body in the solar system. Proteus is quite a bit larger but is almost spherical. It seems likely 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 of water ice with only a small amount of rock.
But unlike most of Saturn's moons, Hyperion has a low albedo (.2 - .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.
The Voyager images and subsequent ground based photometry indicate that Hyperion's rotation is chaotic, i.e. its axis of rotation wobbles so much that its orientation in space is completely unpredictable. There is only one other known body in the solar system (asteroid 4179 Toutatis) that rotates chaotically but simulations seem to indicate that other irregular satellites may have done so in the past. Hyperion is unique in that it is very irregularly shaped, has a highly eccentric orbit, and is near another large moon (Titan). These factors combine to restrict the set of conditions under which stable rotation is possible. The 3:4 orbital resonance between Titan and Hyperion may also make chaotic rotation more likely.
Hyperion's odd rotation probably accounts for the fact that Hyperion's surface is more or less uniform, in contrast to many of Saturn's other moons which have distinctly different leading and trailing hemispheres.
Hyperion 是土星已知衛(wèi)星中距土星第十六近的一顆：
公轉(zhuǎn)軌道：距土星 1,481,100 千米
衛(wèi)星直徑：286 千米 (410 x 260 x 220)
質(zhì)量：1.77e19 千克
在希臘神話中，Hyperion是一個巨人，該亞與烏拉諾斯的兒子，Helios的父親。
它由波德和Lassell于1848年發(fā)現(xiàn)。
土衛(wèi)七是太陽系中的一顆高度不規(guī)則（非球形）天體。海衛(wèi)八稍大一些，但差不多是個球體?？雌饋硗列l(wèi)七像是一顆大星體的碎片，大星體因在遠(yuǎn)古時期的碰撞而碎裂。
就像土星的其他衛(wèi)星，土衛(wèi)七的低密度表明它由少量的巖石混合著冰水組成。
不像土星的其他衛(wèi)星的是，土衛(wèi)七的反照率較小(.2 - .3)，表明它至少覆蓋著一層薄薄的暗色物質(zhì)。這可能是來自遠(yuǎn)于土衛(wèi)八的更暗的土衛(wèi)九上的物質(zhì)。
旅行者號帶來的圖片與基于地的光度測定表明土衛(wèi)七的自轉(zhuǎn)混亂，比如它的自轉(zhuǎn)軸不停搖晃，在空間的方向無法確定。土衛(wèi)七是太陽系已知星體中一顆自轉(zhuǎn)混亂的星體，不過其他星體可能在遠(yuǎn)古時期也這樣。土衛(wèi)七在其他不規(guī)則外形的星體中是獨(dú)一無二的，公轉(zhuǎn)偏心率較大，與另一顆大衛(wèi)星土衛(wèi)六很近。這些因素集合在一起，限制了它穩(wěn)定自轉(zhuǎn)的條件。土衛(wèi)六與七的公轉(zhuǎn)共振比為3:4，使它自轉(zhuǎn)混亂更有可能。
土衛(wèi)七的奇怪自轉(zhuǎn)可能起因于外形的不規(guī)則，與那些具有明顯正半球與后半球的土星衛(wèi)星形成對比。