Blazing objects in Saturn’s weirdest ring
Scientists working with images from NASA’s Cassini spacecraft have discovered strange objects punching through parts of Saturn’s F ring – the planet’s outermost ring – leaving glittering trails behind them.
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Carl Murray, a Cassini imaging team member, said:
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. These findings show us that the F ring region is like a bustling zoo of objects from a half mile [kilometer] in size to moons like Prometheus a hundred miles [kilometers] in size, creating a spectacular show.
Scientists have known that relatively large objects like Prometheus (as long as 92 miles, or 148 kilometers, across) can create channels, ripples and snowballs in the F ring. But scientists didn’t know what happened to these snowballs after they were created, Murray said. Some were surely broken up by collisions or tidal forces in their orbit around Saturn, but now scientists have evidence that some of the smaller ones survive, and their differing orbits mean they go on to strike through the F ring on their own.
These small objects appear to collide with the F ring at gentle speeds – something on the order of about 4 mph (2 meters per second). The collisions drag glittering ice particles out of the F ring with them, leaving a trail typically 20 to 110 miles (40 to 180 kilometers) long. Murray’s group happened to see a tiny trail – what scientists are calling a “mini-jet” – in an image from Jan. 30, 2009 and tracked it over eight hours. The long footage confirmed the small object originated in the F ring, so they went back through the Cassini image catalog to see if the phenomenon was frequent. Nick Attree, a Cassini imaging associate, said:
The F ring has a circumference of 550,000 miles [881,000 kilometers], and these mini-jets are so tiny they took quite a bit of time and serendipity to find. We combed through 20,000 images and were delighted to find 500 examples of these rogues during just the seven years Cassini has been at Saturn.
In some cases, the objects traveled in packs, creating mini-jets that looked quite exotic, like the barb of a harpoon. Other new images show grand views of the entire F ring, showing the swirls and eddies that ripple around the ring from all the different kinds of objects moving through and around it.
The results will be presented April 24, 2012 at the European Geosciences Union meeting in Vienna, Austria.
Bottom line: Scientists working with images from NASA’s Cassini spacecraft have discovered strange objects punching through parts of Saturn’s F ring – the planet’s outermost ring – leaving glittering trails behind them.