Here's a
picture of Saturn's moon Mimas. Remind you of anything? Well, unless you're a fan of the original
Star Wars, probably not.
But here is the
diabolical Death Star with which the forces of The Empire destroyed the planet Alderaan.
As it happens, poor Mimas was the victim of a massive impact, not the aggressor. What we see in the photo is a giant impact crater named Herschel, after William Herschel who discovered Mimas. The crater is 130 km (81 mi) wide, almost a third the size of the of the little moon diameter.