What Two Moons Can Do

Earlier this year the Cassini-Huygens mission studied the delicate F ring that winds a delicate strand of debris around Saturn. The F ring is the outermost of the rings and is only a few hundred kilometers wide.

It turns out that the F-ring is disrupted by the action of the two moons that also work to keep it on the clumpy and narrow. Prometheus and Pandora both interact with the ring, and occasionally they work to disrupt the material in the ring — giving it a somewhat jagged, clumpy, and very ethereal appearance. Prometheus’s orbit encounters the ring and when it does, this tiny moon’s gravitational pull tugs at the ring material, causing the disrupted appearance. It’s almost as if the moonlet is slicing material out of the ring as they move along together around Saturn.

The F ring is made of particles of ice and dust that swarm in orbit around the planet, and was first seen in images from the Pioneer spacecraft. Subsequent Voyager images showed more detail in the ring — and at that time, I remember scientists referring to the “kinky” F ring because of the mysterious knotted structure they were seeing in the Voyager images.

If you could be in a spacecraft hovering above the F ring and watch it for a few hours, you’d see the view changing continually, as it appears to do in this animation (below).  Amazing what we can learn by watching for just a few hours, eh?