Wednesday, April 25, 2012

Strange Objects Punching Holes Through Saturn’s Outer Ring

Strange Objects Punching Holes Through Saturn’s Outer Ring:

By Mark Brown, Wired UK
NASA’s Cassini spacecraft has revealed mysterious kilometer-sized objects that punch through Saturn’s chaotic and ever-changing F ring, leaving trails of ice behind them.
Wired U.K.
The objects pierce the planet’s thin ring at a gentle speed of just two meters per second, and then drag glittering ice particles out into space. The trails are typically 40 to 180 kilometers long. Astronomers are calling the ice trails “mini-jets.”

Cassini imaging team member Carl Murray, based at Queen Mary University of London, said in a press release that the jets unlock some secrets of the curious F ring.
“These latest Cassini results go to show how the F ring is even more dynamic than we ever thought. The F ring region is like a bustling zoo of objects from a kilometer in size to moons like Prometheus a hundred kilometers in size, creating a spectacular show.”
Astronomers have known that large objects like moons Prometheus and Pandora can create channels, ripples and sticky snowballs in the F ring. What they didn’t know, is what happened to these snowballs after they were created. These trails are good evidence that some balls survive, grow and, in their differing orbits, go on to strike through the F ring on their own.
Murray’s group first saw a tiny trail in an image from January 2009. They then went back through the last seven years of Cassini images to see if the phenomenon was frequent. It took some looking — the F ring has a circumference of 881,000 kilometers — but in 20,000 images the team found 500 examples of rogue objects blazing trails.
“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,” said Linda Spilker, a Cassini project scientist at NASA’s Jet Propulsion Laboratory, in the release.
Image: NASA/JPL-Caltech/Space Science Institute [high-resolution]

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