Saturn's outer ring in cosmic light show

Scientists say strange half-mile-sized objects punching through parts of one of Saturn's rings leave glittering trails behind them they've dubbed "mini-jets." The findings, seen in images from NASA's orbiting Cassini spacecraft, fill in a missing link in the understanding of the curious behavior of Saturn's outermost ring, known as the F ring, a release from NASA Jet Propulsion Laboratory in Pasadena, Calif., said Monday. The F ring, perhaps the most active ring in the solar system, has features that can change on a timescale of hours, astronomers say. "I think the F ring is Saturn's weirdest ring, and these latest Cassini results go to show how the F ring is even more dynamic than we ever thought," said Carl Murray, a Cassini imaging team member based at Queen Mary University of London, England. "These findings show us that the F ring region is like a bustling zoo of objects from a half mile to moons like Prometheus a hundred miles in size, creating a spectacular show." Scientists have known large objects like Prometheus can create channels, ripples and snowballs in the F ring, and now believe smaller objects, perhaps created when larger objects break up after passing through the ring, go off in new orbits that mean they can pass through the F ring on their own, creating the visual "mini-jets." These small objects appear to collide with the F ring at low speeds, about 4 mph, and then drag glittering ice particles out of the F ring with them, leaving a trail typically 20 to 110 miles long, such as the ones seen in the Cassini images. "Beyond just showing us the strange beauty of the F ring, Cassini's studies of this ring help us understand the activity that occurs when solar systems evolve out of dusty disks that are similar to, but obviously much grander than, the disk we see around Saturn," Linda Spilker, Cassini project scientist at JPL, said.