This image seemed so otherworldly last night during our bedtime reading of The Spαce Book.
The Cassini spacecraft found cup-like craters filled with hydrocarbons and an extremely low density (determined by the gravitational deflection of the spacecraft during its flyby).
Remarkably, 40% of Hyperion’s interior is empty space between icy fragments, and this also explains the stark surface texture. The compressibility of the moon’s material, and the weak surface gravity help preserve the original shapes of Hyperion’s craters by limiting the amount of impact ejecta coating the moon’s surface. Impactors tend to make craters by compressing the porous surface material, rather than blasting it out. Further, Hyperion’s weak gravity, and correspondingly low escape velocity, means that what little ejecta is produced has a good chance of escaping the moon altogether.
No new moons were discovered around the giant planets of Jupiter, Saturn or Uranus for a half-century between 1789 and 1848, and then Hyperion was found by two independent groups within days of each other.
205 miles across, this peculiar moon tumbles wildly in an eccentric orbit averaging 25x the radius of Saturn. So it is way out there beyond the rings of Saturn (which end at 1.3x the planet’s radius).
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