Bad Astronomy

Side view of the Death Star moon

Saturn’s icy satellite Mimas is the Rick Astley of moons. It got one huge hit* and that’s all it’s been known for ever since.

But the Cassini Saturn probe sometimes sees things a little differently, and recently provided us with a sideways view of Mimas. Literally.

[Click to rickrollenate.]

On January 31, 2011, Cassini snapped this picture of the moon with the planet’s rings in the background. I really like this shot, since we see Mimas’s giant impact crater from the side. I don’t think I’ve ever seen it quite this way before.


A long time ago, Mimas got hit pretty hard with something pretty big. The apocalyptic impact carved a crater 130 km (80 miles) across in the moon, which we now call Herschel. In most pictures we see it from an angle and Mimas winds up looking an awful lot like the Death Star.


But in the big picture above the crater was almost edge-on, and you can see how seriously it messed up the moon: a pretty hefty portion of the edge of Mimas looks flat where the rim of the crater distorts the horizon. An impact this size anywhere on Earth would be, well, bad. Very very very bad. And it’s not like Mimas hasn’t suffered enough, as you can see it’s been hit thousands of times; the surface is saturated with craters.

But that’s the way it is in the solar system. A lot of debris is floating out there, and over billions of years physics cannot be denied. After all… you know the rules and so do I. If you’re a moon, those small objects are gonna run around and hurt you.

* That link is safe. Seriously. I promise. Go ahead, click it. I dare you.

Related posts:

- Wocka wocka wocka Mimas wocka wocka
- The moon that almost wasn’t
- The raw face of the Death Star moon
- Saturn’s million moons cast shadows