A new study is suggesting that Saturn's myriad of medium sized moons might have been created when it's largest moon, Titan, was formed during violent collisions in the ringed planet's orbit.
Saturn has more than 60 known moons, though most of these are rather small and are most likely captured asteroids and the like. Of the ones large enough to have colloquial names though, a new theory has arisen as to how these moons were formed.
The new theory, put forth in a study by Erik Asphaug of the University of California, Santa Cruz, and Andreas Reufer, from the University of Bern, Switzerland, suggests that at one point, Saturn had a number of larger moons, similar to Jupiter's Galilean moons. When these rocks later collided in orbit, they merged to form Titan, Saturn's largest moon, and at the same time, they discarded material during the collisions which later formed the smaller moons.
The discarded material was most likely composed of chunks of icy rock and dust. The dust was eventually attracted to the larger bits of material, and given enough time, would clump together to form the smaller moons, which are a few hundred miles across.
This might be the view from Saturn's moon Titan, looking out over a lake of liquid methane
This theory is interesting because it models the Saturn planetary system's formation after the formation of our solar system: Our eight planets were formed in much the same way – initially, gas is attracted by gravity to form planetary bodies; and later in their development, the larger bodies collide and merge, while casting off excess material which forms smaller bodies.
"These satellite collisions are a regime that is not very well understood, so the modeling opens up new possibilities in general for planet formation," Reufer said.
It is generally agreed that Earth was formed in much the same way; that there were originally two smaller bodies, much closer to each other in size, and that they collided, leaving one planet with more mass and one moon with less.
Their theory is strengthened by the fact that many of Saturn's smaller moons, such as Enceladus and Dione, seem to share the same composition as Titan's mantle, and it would explain why Titan has a high eccentricity – a collision could certainly account for that.
The study is being presented today at an annual meeting for the Division for Planetary Sciences of the American Astronomical Society in Reno, Nevada and will soon be published in the journal Icarus.