Astronomy Picture of the Day

Explanation: Do oceans under the ice of Saturn's moon Enceladus contain life? A reason to think so involves long features -- some dubbed tiger stripes -- that are known to be spewing ice from the moon's icy interior into space. These surface cracks create clouds of fine ice particles over the moon's South Pole and create Saturn's mysterious E-ring. Evidence for this has come from the robot Cassini spacecraft that orbited Saturn from 2004 to 2017. Pictured here, a high resolution image of Enceladus is shown in true color from a close flyby. The deep crevasses are partly shadowed. Why Enceladus is active remains a mystery, as the neighboring moon Mimas, approximately the same size, appears quite dead. An analysis of ejected ice grains has yielded evidence that complex organic molecules exist inside Enceladus. These large carbon-rich molecules bolster -- but do not prove -- that oceans under Enceladus' surface could contain life.