For the first time, astronomers have discovered Saturn’s biggest moon creating a trail of giant snowballs as big as 12 miles in diameter when it enters the innermost edge of the planet’s ring.
The scientists found that the moon, Prometheus, which passes through the innermost edge of the ring in about every 68 days, lifts out ring particles which then begin to clump and take on a life of their own over time.
According to the scientists, the larger and closer satellite of Saturn cruises a bit faster than the particles in the ring and is slightly inclined relative to the ring’s plane.
It collides with the diffuse, inner edge of the F-ring (the outermost ring of the planet) where the moon’s gravity is strong enough to pull streamers of particles from the ring, creating channels.
Over time, the disrupted particles — mostly dense, sticky ice — can take on a life of their own, clumping together under their own growing gravitational force, said the scientists who discovered the phenomenon by analysing images by Nasa’s Saturn-orbiting Cassini spacecraft.
“We’ve never actually seen this before. You can see a real cause and effect. These objects didn’t exist before Prometheus passed,” lead researcher Carl Murray, with Queen Mary, University of London, told Discovery News. Future visits by Prometheus could stoke a snowball’s growth — or it could destroy it, they said.
“Once Prometheus passes by, it gives these objects a kick. They have about 68 days to sort of get things together before Prometheus comes around again,” Murray said.
“Whether at the end of the day you end up with a fully formed satellite we don’t know. That’s something we want to look at. Maybe these objects are precursors of fully formed satellites,” he said.