Saturnian rings and the formation of the solar system

Explanations that I’ve seen of the formation of the solar system describe orbiting debris that coalesces into planets. My question is why did that happen, while debris continues to orbit Saturn without pulling together to form larger bodies?

The Saturn thing is different. The debris forming Saturn’s rings hasn’t been there very long and won’t be there much longer (by astronomical standards). It doesn’t coalesce because it isn’t massive enough to generate enough gravity to oppose all the disruptive gravitational forces of Saturn and its moons.

Hey Lib

This Nine Planets webpage explains that some of the small moons of Saturn are important in keeping the rings in place. It also points out that the material of the rings, if collected together would only make up a moon of about 100km diameter–which would be smaller than Saturn’s eleventh smallest satellite, about the size of Pandora. Don’t go there.

Note that the Sun has a “ring”, too: the asteroid belt! The reason these never coalesced into a planet is probably Jupiter’s gravity, large enough to disrupt any incipient planet.

The reason that Saturn and the rest of the outer planets have rings is that the ring material is close enough to the planet so that the planet’s gravity keeps it from coalescing. There is a name for the limit within which no moon can form, which I can’t think of off the top of my head. Astronomers will soon be here to amplify on this, I’m sure.

The reason that Saturn and the rest of the outer planets have rings is that the ring material is close enough to the planet so that the planet’s gravity keeps it from coalescing. There is a name for the limit within which no moon can form, which I can’t think of off the top of my head. Astronomers will soon be here to amplify on this, I’m sure.

I’m going to take a risk here, by posting off the top of my head without checking my facts. When I do that, I’m often wrong, but I’ll do it any way.

The term Exapno Mapcase is looking for is “The Roche Limit”.

Yes, indeed, Saltire, the Roche limit is correct.