Just like the title says, how dangerous would it be for the inhabitants of a planet if the moon had rings? Assuming that the planet is roughly the size of Earth and the moon is a little bigger than ours. Would the inhabitants risk annihilation by asteroids from the rings?

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    $\begingroup$ I'll let someone more knowledgeable answer, but I'm pretty certain it couldn't exist in the first place, at least not for long - it just wouldn't be stable, but I think you're right, in a way, there'd be flying debris until a long-term stable state was reached. One thing, what has the magic tag to do with your scenario? I'll edit to rationalize them, feel free to revert if you see fit. $\endgroup$ – Draft 85 Jan 28 at 22:08
  • $\begingroup$ If the question gets closed, then what might help would be if you would tell us about the orbital distances, and timescales after system formation if possible. Also if the inhabitants are recent or indigenous for a bit of context, that wouldn't hurt. If that all sounds a bit technical, then why not ask another question to establish parameters. $\endgroup$ – Draft 85 Jan 29 at 1:57

Not At All, For Two Reasons

First, if a moon's ring system extended far enough to overlap the location of its parent planet, the rings wouldn't form in the first place, since no ring can form where a planetary body sweeps them out (part of why Saturn's moons don't fall within its ring system). So the rings wouldn't rain down on the planet, because if they were in a position to do so, they would never have formed.

Second, rings are sparse things. Saturn has glorious rings, but their entire mass is 40% that of Mimas - or about a millionth the mass of Earth. It's a lot of mass, in human terms, but in planetary terms, it's very little mass spread over a very large space. The chunks of matter in those rings average about 10cm.

A moon with about the mass of our moon (maybe a little more) would have a much more tenuous ring, comprised of dust. So even if the host planet didn't sweep its orbit clean before any occupants could be endangered (it would), a moon's ring system would not present any peril.

  • $\begingroup$ Thank you very much! $\endgroup$ – Wh1tl0w Jan 30 at 16:17

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