I would like my world's solar system to have a super saturn (J1407b) like planet with ring system for astrological reasons. How could I have this during a "contemporary age" (Cenozoic equivalent on the Earth-like planet so the system is already about 4-5 billion years old.)

Known issue: If the rings form from protoplanetary disk they'd be largely accreted into exomoons by the time frame required.

  • $\begingroup$ If you're asking from the perspective of the Real World where PhDs will judge the quality of your design, this question should have been asked on Astronomy. If you're asking from the perspective of an imaginary world (our stated goal in the help center) where you don't expect to be judged by PhDs but, rather, you expect to have fun using known discovery to imagine the SciFi ideal of "what if?," then this could be rationalized as the ring density is lower than we find in our own Saturn, slowing accretion, and allowing the planet to exist in your solar system's Cenozoicesque age. $\endgroup$
    – JBH
    Commented May 27 at 19:19
  • $\begingroup$ Is there a reason that whatever works here for Saturn wouldn't work in your case? $\endgroup$ Commented May 27 at 20:57
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    $\begingroup$ The sheer size/diameter of the rings is the most problematic thing since it require an Earth's worth (maybe more) of mass. $\endgroup$
    – Cato
    Commented May 28 at 0:40
  • $\begingroup$ @Cato I think you're getting stuck on what you assume will happen. Let's say the s-saturn has a ring system so large that it has five Earth-masses in the rings alone. That won't definitively cause planets to form. It depends on the density of the mass in the rings (which changes the size of the rings). This Stack's sweet spot is helping suspend disbelief - and that means coming up with a rationalization for how your s-saturn can exist in your story/universe. Frankly, our Saturn is 95 Earth-masses. By your logic, it should be partitioning off into chunks of planetary mass - but it hasn't. $\endgroup$
    – JBH
    Commented May 28 at 4:48
  • $\begingroup$ I'm a bit confused as to what planet you are referring to? The planet itself isn't what I'm worried about partitioning off into chunks, I'm moreso worried that a ring system of such diameter (roughly 75%-100% of an astronomical unit) would be dismantled and accreted into exomoons before the Cenozoic age. The reason for this worry is that scientists seem to believe J1407b's rings will only last a couple thousand orbits (not specific but I'd guess in the manner of a couple hundred thousand years) The rings don't need to be a full AU in size, just noticeable with the naked eye from my earth-like. $\endgroup$
    – Cato
    Commented May 29 at 4:27

1 Answer 1


Simple solutions:

  • capture of icy asteroids or comets, that get broken down by tidal forces during capture and lose part of their energy while interacting with the high atmosphere of the planet. Part of the fragments fall on the planet, part keep orbiting it forming a ring structure.

  • Impact event on one of the moons: some of the ejecta produced by the impact will end up being capture by the planet gravity and will start orbiting it, producing a ring structure.

  • Moon volcanism: the volcanic ejecta might escape the moon gravity well and end up orbiting around the planet, forming again a ring system.

  • $\begingroup$ Do you think it plausible for these forces to from a ring that is similar in diameter to J1407b? The diameter I'm looking at is anywhere between 75%-100% of a full astronomical unit. $\endgroup$
    – Cato
    Commented May 27 at 17:55

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