NASA’s Cassini orbiter’s latest snapshot of Saturn has revealed the rapidly rearranging rings of the planet, as well as colliding moonlets, and an oxygen atmosphere.

Scientists were surprised to find that the atmosphere around Saturn’s rings is largely made up of oxygen.

“Most people thought the ring atmosphere would be water molecules,H2O and their breakdown products H (hydrogen) and OH (hydroxyl),” Cuzzi said. That the ring system would have the chemistry to turn hydrogen and hydroxyl into oxygen “was not foreseen by most.” The discovery could help solve a long-standing mystery of Saturn’s rings: why some of them seem stained red.

“Perhaps the colour is imparted when metals in ring rocks interact with oxygen,” said Cuzzi. Also, the most detailed imagery of Saturn’s rings yet is giving a very different and dynamic feel to the orbiting bands of ice chunks.

“Here’s this giant crystalline structure, stretching two-thirds of the distance from Earth to the moon, and yet parts of it change on a monthly or weekly time scale,” said planetary scientist Jeff Cuzzi, from NASA’s Ames Research Center in Moffett Field, California.

The edges of the thickest of Saturn’s rings, A and B, for example, “kind of flop back and forth, sometimes pointing one way and sometimes another, sloshing around like water in a tank,” said Cuzzi, co-author of one the new studies.

These fast-warping edges, he said, underscore the newfound, fluid like nature of the rings.

Saturn’s rings seem to be much like the dusty, rocky disks around stars where planets form, according to Cassini team member Larry Esposito, of the University of Colorado in Boulder.

If the ring system is in fact a reasonable facsimile for a planet nursery, Saturn may change our understanding of how planetary disks behave. Thanks to Cassini’s close-up view of Saturn’s rings, “we can see structures and phenomena that we would not have otherwise imagined existed in planetary disks,” said Esposito, co-author of one the new Saturn studies. Also, recent studies have uncovered dozens of mysterious moonlets, several kilometres in size, bouncing around like bumper cars in the slim, outermost ring, called F.

“These cannonballs are whizzing through the F ring and colliding with things,” Cuzzi said. “What are these things? Where did they come from?” he pondered.

“This doesn’t strike us as a particularly stable situation,” he added.