Image: The low density of Hyperion indicates that this satellite is mainly composed of ice with a small amount of rock. Hyperion's rotation is chaotic, its axis of rotation varies so greatly that its orientation in space is impossible to predict. Hyperion is unique in its wasp-nest shape, and its surface riddled with strange craters could conceal a vast network of caves.
Hyperion observed up close is one of the strangest objects in the solar system. This small, very dark, reddish moon of Saturn measures 266 km in average diameter. It is an incredibly squishy, irregularly shaped body.
Hyperion has numerous dark meteorite craters on its surface, the largest of which measures 120 km in diameter and 10 km deep.
Its enigmatic, deeply cratered surface has a unique appearance; no other moon in the solar system resembles it; moons generally have a more or less smooth surface.
Beneath its dark surface, a few tens of meters thick, we can discern shiny materials. Hyperion's low density indicates that this moon is mostly ice with a small amount of rock and lots of empty space. This potatooid looks like a sponge or a wasp nest.
The walls of impact craters are bright like a skating rink, while the floors of the craters are a dull reddish coloration. Of course there is no lava, the average temperature on Hyperion, as on many moons, is -180 degrees Celsius. On Hyperion all molecules are frozen, carbon dioxide, water, methane, carbon dust and hydrocarbons.
Saturn's rebellious little moon rotates chaotically, as if tossed around in an eccentric orbit. In other words, the object does not rotate at a constant speed or in a constant orientation, its axis of rotation varies enormously. No latitude longitude reference system could be established for this moon. This is due to the pull of Saturn and the large moon Titan.
Hyperion resonates with Titan, Titan makes four orbits around Saturn when Hyperion makes three. When Hyperion passes by, very close to Titan, it undergoes a complex set of gravitational variations because Hyperion is 20 times smaller than Titan. Its rotation and its orbit are very affected, Titan has a diameter of ≈5150 km. Titan is larger than Mercury.
But this 3:4 resonance with Titan allowed it to keep all its freedom of rotation, in fact without Titan, the rotation of Hyperion on itself would be synchronous, locked facing the enormous planet Saturn.
But this is not the case, while the enormous moon Titan is locked in synchronous rotation with Saturn, the small Hyperion rotates freely on itself in approximately 13 days and around Saturn in 21 days. This allows it to better distribute the low heat received. Hyperion therefore lives on an island of orbital stability which allows it to show all its faces to our space probes to the delight of scientists.
