Pack up your things! Discover reports that the Cassini Saturn probe has found an oxygen atmosphere around Rhea:
Other atmospheres known to exist throughout the solar system, like that of Titan as well as Jupiter’s moons Europa and Ganymede, were discovered and studied from afar. Rhea’s, however, is so thin that this direct pass through it was the only way to be sure it was there.
The astronomers believe the same process that creates the atmospheres of Europa and Ganymede is also at work on Rhea: Charged particles strike the ice on the surface, breaking it apart and freeing molecules to feed the moon’s thin envelope.
“All this suggests these kinds of exospheres may be very common,” said Dr. [Ben] Teolis. “There are different moons at Saturn and at Uranus, for example, which should be massive enough to hold an atmosphere. And, presumably, this kind of thing is duplicated billions of times throughout the galaxy. This could be something happening all over the place.” [BBC News]