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.

2012 February 8
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Enceladus Backlit by Saturn
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA; Color Composite: Gordan Ugarkovic

Explanation: 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 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.

APOD in India: APOD editor to speak in Delhi on Feb. 12 (registration required)
Tomorrow's picture: dancing green

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