for National Geographic News
Small moons within one of Saturn's faintest rings may occasionally collide with other large ring particles on a near-daily basis, a new study suggests.
Scientists tracked the pinball-like action by looking at changing patches of dust in Saturn's active F ring, which was discovered in the late 1970s.
The ring is patterned with twisted braids and a spiral structure, thanks in part to interactions with two small, nearby moons, Prometheus and Pandora.
"The F ring has fascinated me ever since I saw the Voyager 1 images back in 1980," said study lead author Carl Murray of Queen Mary, University of London.
Murray and his team used the Cassini spacecraft to capture the most recent images.
"One of the reasons I got involved in Cassini was to try to understand this bizarre ring," he added by email.
How Saturn's ring system formed remains a mystery. The rings could be remnants of the same gas and dust that formed Saturn, some experts say.
(Related: "Moonlet Study Sheds Light on Origins of Saturn's Rings" [October 24, 2007].)
Murray's team pieced together digital images to create 360-degree mosaics of the entire ring over time.
In November 2006, he said, the ring was relatively quiet. But in late December, a three-mile-long (five-kilometer-long) object known as S/2004 S 6—or possibly another object on a very similar orbit—appears to have begun passing repeatedly through the core of the ring.
That caused a series of collisions, producing numerous bright "jets" of material.
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