Saturn's Rings Bombarded by Meteor Showers: NASA's Cassini Reveals New Evidence

Some of the meteoroids near Saturn are making quite the impact--literally. NASA's Cassini spacecraft has recently provided the first direct evidence of these small missiles breaking into streams of rubble and crashing into Saturn's rings.

The solar system is full of small, speeding objects. However, scientists are rarely able to observe their impacts as they occur. The recent observations with Cassini place Saturn's rings as the only location besides Earth, the moon and Jupiter where researchers have been able to observe these collisions while they're actually occurring.

The small objects that pummel Saturn range from about one-half inch to several yards in size. It took years for the researchers to actually distinguish the tracks left by nine meteoroids in 2005, 2009 and 2012. Out of these three years, though, 2009 was the best time to see the debris left by meteoroid impacts. The very shallow sun angle on the rings caused the clouds of debris to look bright against the darkened rings in images.

Saturn's rings act like very effective detectors of many kinds of surrounding phenomena, including the interior structure of the planet and the orbits of its moons. For example, a subtle but extensive corrugation that ripples about 12,000 miles across the innermost rings tells of a very large meteoroid impact in 1983. The latest findings, though, reveal that current-day impact rates for small particles at Saturn are about the same as those at Earth.

The researchers believe that smaller meteoroids probably break up on their first encounter with the rings, which create even smaller and slower pieces that then enter into orbit around the planet. The impacts from these secondary meteoroid bits into the rings kick up clouds formed of tiny particles. These particles have a range of orbit speeds around the planet and the clouds that they form are soon pulled into diagonal, extended bright streaks.

"Saturn's rings are unusually bright and clean, leading some to suggest that the rings are actually much younger than Saturn," said Jeff Cuzzi, co-author of the paper, in a news release. "To assess this dramatic claim, we must know more about the rate at which outside material is bombarding the rings. This latest analysis helps fill in that story with detection of impactors of a size that we weren't previously able to detect directly."

The findings are published in the journal Science.