For example, if you look closely, you will notice that in one of the darker divisions of Saturn's inner rings, there is another, narrower ring. The strange shape you ask about is because it is not a circular ring, but rather an elliptical profile. What we don't know for sure is whether the changing configurations of Saturn's satellites actually modify the position of the ring divisions, or whether the rotation of the rings around the planet presents different structures to the eye.
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