Unnoticed Moonlets Live and Die in Saturn's Rings

Birth and death is happening constantly in the rings of Saturn, and researchers are only just now dragging these dramatic events under the public spotlight.

No, there isn't some kind of alien civil war occurring amidst the rings of Saturn, but that doesn't mean there isn't destruction a-plenty.

According to a study recently published in the journal Icarus, small moons are constantly born and then destroyed in a very short amount of time compared to the average formation and destruction window of most heavenly bodies.

These moons, called moonlets, can be seen in photos recently captured by NASA's Cassini spacecraft, as well as in 30-year-old pictures taken by the Voyager mission. They found that significant changes can especially be seen in the F-ring of Saturn's moons, where fewer "bright lumps" are visible in the icy ring than a few decades ago.

Amazingly, modern footage has revealed that these lumps can come and go over the course of hours or days.

"We believe the most luminous knots occur when tiny moons, no bigger than a large mountain, collide with the densest part of the ring," Robert French, of the Search for Extraterrestrial Intelligence (SETI) Institute, explained in a recent release. "These moons are small enough to coalesce and then break apart in short order."

"These newborn moonlets will repeatedly crash through the F ring, like bumper cars, producing bright clumps as they careen through lanes of material," added SETI's Mark Showalter. "But this is self-destructive behavior, and the moons - being just at the Roche limit - are barely stable and quickly fragmented."

This Roche limit he mentions is the exact distance that is too close to a planet's gravitational pull for moon stability. French astronomer Edouard Roche was the first to point out that if a moon orbits too close to its neighboring planet, the difference in gravitational tug on its near and far side can tear it apart.

And the F-ring is right at this boarder, far enough from Saturn to make moons from drifting matter, but close enough to have them quickly torn apart once more.

Still, this is all very much just speculation, and the authors add that if their theory is correct, then Saturn should be soon be slipping into a waxing period soon, in which more and more bright moonlets will start forming in the F-ring. We will just have to wait and see if they are right.