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Posted by Mystery History TV

Cassini got its best-ever view of Saturn's moon Helene on June 18, 2011, when it approached to within 7,000 kilometers. Helene is a co-orbital moon of Rhea. The sunlit face is mostly the side of the moon that always faces Saturn, and is covered with strange gully-like features.

The surface appears to "beat" with contrast changes because Cassini was cycling through different filters to take the images. In short-wavelength filters, the areas between gullies are darker than the smooth gully floors, while there is less contrast between them in the longer-wavelength filters.

To generate this animation, the frames were aligned. Then the Photoshop "dust and scratches" filter was used to remove most of the cosmic ray hits (which also removed a bit of detail from gully areas), and remaining cosmic ray hits were cleaned up using the clone tool. Contrast was adjusted to push black space to completely black and to bring out some more detail in shadowed areas.

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