As if Titan was not exciting enough, the Cassini space probe recently detected an atmosphere around a second Saturnian moon, this time Enceladus. Cassini did not spot the atmosphere directly but discovered that Saturn’s magnetic field lines are being bent in the vicinity of Enceladus. This indicates diversion of the field by an atmosphere.
Because the moon is too tiny (according to NASA it would fit inside the state of Arizona) to hold an atmosphere for long, the atmosphere must be dynamically sustained. Scientists believe that this discovery is related to current tectonic activity on the moon. Much of Enceladus’ surface is young and the snow white brightness of the planet also implies recent resurfacing. Theories include active ice volcanoes and geysers and/or plate tectonics that bring pristine materials from the moon’s interior to the surface. If confirmed, the Saturnian system may prove to be much more dynamic than previously conceived.
The background image is Enceladus in false-color to bring out some of the surface composition differences. The faded gray behind Enceladus is a portion of Saturn (giving a hint at just how massive the planet really is compared to a tiny fleck of dust like Enceladus). The foreground image is an artist’s concept of the atmosphere’s affect on Saturn’s magnetic field.