... one of
Jupiter's moons, which you'll know if you've read Space Oddity 2010 (or was it 2050? Sequelitis, all of them). (OK, it was "... oddessy. Pardon an old Bowie fan.)
Click for big pic
Isn't that gorgeous?
I love images which combine order with a certain kind of chaos, combine simplicity with a certain kind of complexity.