слово дня: moonlet

Observing the same propeller on both the lit and unlit sides allows scientists to gather richer information about how the moonlet affects the ring. For example, in the unlit-side view, the broad, dark band through the middle of the propeller seems to be a combination of both empty and opaque regions.

The views show the object from vantage points on opposite sides of the rings. The top image looks toward the rings' sunlit side, while the bottom image shows the unilluminated side, where sunlight filters through the backlit ring.
The two images presented are reprojected at the same scale (0.13 mile or 207 meters per pixel) in order to facilitate comparison.

Here, as Cassini moved in close to the rings as part of its ring-grazing orbits, it was able to obtain this extreme close-up view of the propeller, which enables researchers to examine its effects on the ring as never before.
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The dark bands are regions where the density is so high that the ring becomes opaque to the sunlight filtering through the rings.
Image scale in this view is 0.3 mile (500 meters) per pixel.