Cassini’s reporting that Enceladus, the highly reflective moon of Saturn, has an atmosphere. That’s rather interesting, as its mass isn’t enough to support a permanent atmosphere gravitationally, so it must be being replenished somehow. If that’s the case it must be geologically active, likely as a result of gravitational tides. It also looks increasingly likely that it’s this activity that’s creating Saturn’s E-ring – the outermost ring that’s composed of slightly different particles from the rest.