Cassini Spacecraft Detects Ice Bullets Shooting Through Saturn’s F Ring


Video courtesy of NASA

Saturn’s rings are under fire – literally. NASA has discovered weird objects; some of them measure a half-mile in length. These cosmic bullets slam through the gas giant’s beautiful rings, leaving behind glittering trails of stardust (actually these trails are made of ice). These findings were made via the Cassini spacecraft and announced this week at the Geosciences Union meeting in Vienna, Austria. 

These bodies are hammering away at the outermost of Saturn’s rings – the F ring. This ring is approximately 550,000 miles (881,000 kilometers) in circumference – to put this in perspective – Earth is 24,000 miles (40,000 kilometers) in circumference. These trails of ring-matter have been dubbed “mini-jets” by scientists. More than 500 of them have been detected in the seven years that Cassini has been in the Saturnian system.


The Cassini spacecraft has discovered objects plowing through Saturn's F ring. These objects have created what are being dubbed "mini-jets" and leave a stream of sparkling ice in their wake. Photo Credit: NASA/JPL

“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, Cassini project scientist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

Technically terms such as “slam” and “hammering” – might not be exactly accurate. The projectiles penetrate the F-Ring at about 4 mph a second – relatively slow in cosmic terms. These smash-ups result in glittering trails approximately 20-110 miles (40-180 kilometers) in length.

These bizarre objects can plummet through the F ring in packs and leave features in the mini-jets that resemble the hooks in a harpoon. Photo Credit: NASA/JPL

“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, U.K. “These findings show us that the F ring region is like a bustling zoo of objects from a half-mile (0.8-kilometer) in size to moons like Prometheus a hundred miles (160.9 kilometers) in size, creating a spectacular show.”

These objects have strange characteristics. Some travel in packs – like wolves, others make mini-jets resembling the barbs of a harpoon. Throughout the period that these images were being taken incredible features were discovered as these objects moved in and around the planet’s F ring.

“The discovery of small objects in the F ring, and how they behave, helps us refine our understanding of the evolution of Saturn’s rings. The rings are an amazing dynamical laboratory for studying how planets form, and the F ring, with its small clumps, is a particularly good place for these kinds of studies,” Spilker said. “The highly productive Cassini mission has significantly altered our understanding of the Saturn system and will continue to enhance our insight into Saturn’s place in the solar system for years to come.”

Although they appear smooth in Earth-based telescopes, Saturn’s rings are comprised of clumps of water ice. These pieces encircle the planet a total of 85,000 miles (140,000 kilometers) from Saturn’s center.

This illustration displays Saturn's primary rings as well as the gas giant's moons. Image Credit: NASA/JPL

“I am excited about Cassini’s potential to reveal even more about Saturn’s intriguing rings.  Who knows what the F ring will do next as it changes before our eyes,” Spilker said.


Video courtesy of JPL/NASA

New images and movies of the mini-jets are available at:

For information about Cassini, visit:

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