Snowy Enceladus

Saturn's moon Enceladus has no atmosphere, but that doesn't mean it lacks "snow." Researchers studying images taken by the Cassini probe have determined much of the material-- ice crystals-- thrown into space by Enceladus' famous geysers falls back to the surface of the moon in a constant, extremely light snowfall.

By comparing the rate of the snowfall to the depth of ice on the surface scientists have concluded the geysers have been active for perhaps tens of millions of years. That in turn implies the heat source that powers the geysers is long-lived, which strengthens the case for a liquid water ocean existing under the surface ice, and also increases the possibility of life in that ocean.