The strangest moon in the Solar System
J Thoendell stashed this in Space
In fact, the second of Saturn’s moons ever discovered, Iapetus, presented a tremendous mystery to Cassini. While it clearly orbited Saturn like the other moons, it was only visible during half its orbit, remaining completely invisible during the other half.
As telescope technology improved, we discovered why: one half of Iapetus is only about one-fifth as bright as the other!
What a strange occurrence. Thanks to Cassini — the NASA mission, not the Italian scientist — we’ve actually gone to Iapetus itself to photograph it, finding that in fact one side looks like it’s been plowing into a dirt storm. Your car’s windshield might look like this after driving through a particularly dense patch of insects, but what could be causing this on Iapetus?
For a long time, this remained a mystery.