Saturn’s moonlet belt - October 25, 2007
In an interplanetary attempt to keep up with the Joneses, Saturn has, with the help of some University of Colorado astronomers, revealed more moonlets in its rings.
Earlier this month we reported that moonlets expected to be seen in a NASA fly-past of Jupiter were mysteriously absent, although some ‘moon-like’ lumps of material were found.
Saturn’s moonlets were probably created when a larger moon was annihilated in a collision with a comet or asteroid, according to Miodrag Sremcevic, lead author of a study published this week over at Nature proper (subscription required). “There was probably a bigger moon of at least 20 miles (32 km) in diameter or larger orbiting at that place. And that moon had the unfortunate fate to be struck by a large meteoroid [sic] or comet and was destroyed into pieces. And now what we see today are the remaining shards of that moon,” Reuters reports him saying.
The moonlets’ presence is indicated by propeller-like features that form in the ring around them. Although four of these features were detected in 2006, new evidence shows that there is actually an entire belt of moonlets around Saturn, probably consisting of thousands of mini-moons ranging from the size of “semi-trailers to sports arenas”, according to the UCB press release. However the moonlets were probably not formed by a single massive collision, as they are not spread uniformly. Instead their distribution supports a cascade of collisions in the ring, triggered by the more recent break up of a large moon. “We all expected they would be everywhere in the ring. Our study shows they are concentrated in certain regions in the ring like a belt,” Sremcevic told Space.com.
Image: Propeller features / NASA/JPL/Space Science Institute/University of Colorado