Enceladus

A small inner moon of Saturn, Enceladus is only about 500 kilometers in diameter.
But the cold, distant world does reflect over 90 percent of the sunlight it receives,
giving its surface about the same reflectivity as new-fallen snow. Enceladus shows a
variety of surface features and very few impact craters - indicating that it is an active
world even though this ice moon should have completely cooled off long ago. In fact
the fresh, resurfaced ppearance of Enceladus suggests that an internal a mechanism,
perhaps driven by tidal pumping, generates heat and supplies liquid water to geysers
or water volcanos. Since Enceladus orbits within the tenuous outer E ring of Saturn,
the moon's surface may be kept snow-bright as it is continuously bombarded with icy
ring particles. Eruptions on Enceladus itself would in turn supply material to the E ring.
Interplanetary ski bums take note: tiny Enceladus has only about one hundredth the
surface gravity of planet Earth.

This moon is shining by the light of its planet. Specifically, a large portion of Enceladus
pictured above is illuminated primarily by sunlight first reflected from the planet Saturn.
The result is that the normally snow-white moon appears in the gold color of Saturn's cloud
tops. As most of the illumination comes from the image left, a labyrinth of ridges throws
notable shadows just to the right of the image center, while the kilometer-deep canyon
Labtayt Sulci is visible just below. The bright thin crescent on the far right is the only part
of Enceladus directly lit by the Sun. The above image was taken last year - 2011 -
by the robotic Cassini spacecraft during a close pass by by the enigmatic moon. Inspection
of the lower part of this digitally sharpened image reveals plumes of ice crystals thought to
originate in a below-surface sea.