The Real-Life Death Star

Saturn has 62 moons.  One of them, called Mimas, looks familiar to anyone who’s ever watched the original Star Wars:  it’s a dead ringer for the Death Star.

Mimas is weird in other ways, too.  It’s the smallest round moon ever discovered.  It has an apparent impact crater so large that it looks like it should have shattered the moon into tiny pieces.  And Mimas accountably wobbles, too.  In fact, it wobbles so dramatically that scientists are stumped about how the pronounced wobble could possibly be caused.  The competing theories range from some large stone under the surface of the impact crater, to a core that is unaccountable shaped like a rugby ball, to an underground ocean that is sloshing back and forth even though Mimas is so cold that it’s hard to see how liquid water can exist.  And so, the scientists argue.

Let’s see — the smallest round moon known to anyone that looks exactly like the Death Star.  Isn’t the real answer obvious?  Help us, Obi-Wan Kenobi!  You’re our only hope!