NASAのインスタグラム(nasa) - 5月17日 05時10分

Most planetary rings appear to be shaped, at least in part, by moons orbiting their planets, but nowhere is that more evident than in Saturn's F ring. Filled with kinks, jets, strands and gores, the F ring has been sculpted by its two neighboring moons Prometheus (seen here) and Pandora. Even more amazing is the fact that the moons remain hard at work reshaping the ring even today.

Prometheus (53 miles, or 86 kilometers across) shapes the F ring through consistent, repeated gravitational nudges and occasionally enters the ring itself. Although the gravitational force of Prometheus is much smaller than that of Saturn, even small nudges can tweak the ring particles' orbits to create new patterns in the ring.

This view looks toward the sunlit side of the rings and was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 21 2016.

Credit: NASA/JPL-Caltech/Space Science Institute
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