Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2018 July 1
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Fresh Tiger Stripes on Saturn's Enceladus
Image Credit: NASA, ESA, JPL, SSI, Cassini Imaging Team

Explanation: Do underground oceans vent through the tiger stripes on Saturn's moon Enceladus? Long features dubbed tiger stripes are known to be spewing ice from the moon's icy interior into space, creating a cloud of fine ice particles over the moon's South Pole and creating 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 from a close flyby. The unusual surface features dubbed tiger stripes are visible in false-colour blue. Why Enceladus is active remains a mystery, as the neighbouring moon Mimas,approximately the same size, appears quite dead. A recent 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.

News: Complex Organics Bubble up from Ocean-world Enceladus
Tomorrow's picture: deep sky colours


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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