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Can you see stars from the surface of a ringed planet?

  1. Apr 9, 2012 #1
    I am writing a novel set on a ringed planet. The plot calls for the rings to be about a thousand years young, more a torus of gas and dust and speeding moonlets. Would a person standing on the night side of this planet be able to see stars? Or would the rings scatter enough light from the sun to obscure them? I was thinking a person would only be able to see stars in the shadow that the planet would throw across the rings.

    Any help would be appreciated.

    Jim Jenkins
  2. jcsd
  3. Apr 9, 2012 #2

    Filip Larsen

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    Gold Member

    Welcome to PF!

    A few comments off the top of my head:

    • I would expect the likelihood of rings to form to depend on the size of the planet, distance to its sun, and likelihood of the planet of capturing a moon. The more massive a planet the bigger the likelihood that a moon ends up in orbits inside the Roche limit [1] of the planet thus providing material for the ring.
    • Any ring material would "quickly" end up in a single orbital plane (rather than a torus) due to collision between ring material. If the planet has any significant bulge of equator I would guess that the orbital plane of the ring is likely to coincide with equator of the planet.
    • If the rings have a relatively high albedo [2] and the rings angle with the incoming sunlight is just right it seems plausible to me that the reflected light from the rings could swamp out the light of all or most of the stars on the night side of the planet, especially if reflected light gets scattered in the atmosphere.

    Others here may provide you with better comments.

    [1] http://en.wikipedia.org/wiki/Roche_limit
    [2] http://en.wikipedia.org/wiki/Albedo
  4. Apr 9, 2012 #3
    Filip Larsen presents a good discussion; but I disagree with his conclusions.
    The highest albedo the rings could have, would probably be about the same as the moon---but the coverage would be far worse (i.e. its a collection of particles, instead of a solid disk). The moon certainly decreased the number of stars you can see near-by it, but you can definitely still see bright stars. Therefore, I would expect that for a very high density, high albedo rings -- you would be able to see only a few very bright stars near the rings itself, but looking away from the rings, you would still be able to see many stars.

    As you decrease the density and albedo of the rings, the more/dimmer stars would be visible.
  5. Apr 10, 2012 #4
    Thanks for replying so quickly and completely. You confirmed what I suspected about viewing stars from the surface of a ringed planet. I wanted to drop a hint that maybe the planet was Mars, where the terra forming had failed, and maybe that blue star mostly hidden by the rings was Earth. It looks like I can safely do that. Thanks a bunch.

    Jim Jenkins
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