Journal Express, Knoxville, IA

CNHI/SE Iowa

February 20, 2013

Saturn's kinky rings explained

(Continued)

Both moons have orbits that are slightly elliptical and slightly tipped with respect to the rings. That means, as they orbit, they move toward and away from the F ring, Prometheus more than Pandora. As it moves toward the ring, Prometheus' gravity drags material away from it, creating those fans and kinks in the ring, as well as the faint spiral pattern of material inside the ring. Oddly, even though it does pull some of the material out of the ring, the overall effect of Prometheus is to keep the particles inside the ring. The interaction is complex and somewhat counterintuitive, but this video put out by NASA might help.



The F ring is constantly changing, sometimes on a scale of just hours. Saturn is a huge, fiendishly complex system, and we knew it would be weird when we got there, but I don't think anyone suspected just how weird it would be. And we discovered all this because we sent a probe there that could stay there, orbiting the planet over and again, looking at as much as it can over as long a period of time as it can.

Phil Plait, the creator of Bad Astronomy, is author of "Bad Astronomy: Misconceptions and Misuses Revealed, from Astrology to the Moon Landing 'Hoax' " and "Death from the Skies! These Are the Ways the Universe Will End."

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