This is more for fluff and illustrative exotica, but I'm keen on an idea where my new world has a moon that orbits elliptically, but has a fast inward close orbit followed by a longer round trip the other way. I just want a moon that rather than being observed waxing and waning, becomes distinctly smaller and then bigger to the point where it is a large presence in the sky.

As I say, it's more an aesthetic than practical notion. But if, in reality, such an orbit would start ripping oceans up and crushing forests, then I'll chuck a nebula into the sky or something... As usual, I've tried and failed to get my head round the "Astrophysics for dummies" blogs and articles that explains this stuff via wikipedia and such.

Any thoughts, views or opinions on whether any major physical impacts as a result of this phenomenon would massively effect a human settlement, would be really helpful.

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    $\begingroup$ "Any thoughts, views or opinions on this" is an unbounded, subjective topic and may result in this being closed as primarily opinion-based or needs more focus. If you're concerned with the natural phenomena that may result from this type of orbit, I would strongly suggest changing your in-body question to indicate this. $\endgroup$
    – Frostfyre
    Dec 20, 2019 at 15:21
  • $\begingroup$ Looks like all big moons in solar system have near-circular orbits. However, I don't know whether this is a law of orbital mechanics or just a tendency. $\endgroup$
    – Alexander
    Dec 20, 2019 at 19:38
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    $\begingroup$ Big moon means big planet it is a moon of. Means big tidal influences. Means tidal circularization works faster. en.wikipedia.org/wiki/Tidal_circularization $\endgroup$
    – puppetsock
    Dec 20, 2019 at 20:29
  • $\begingroup$ You could reasonably simplify this question into "how realistic is this" (with a reality-check flag), and based on the responses to that, think about asking for further ideas. As it stands, this question is too unfocussed. $\endgroup$ Dec 20, 2019 at 20:36

1 Answer 1


An idea how to use such a moon. Create some religion that take this moon as holy symbol, and depending how close is this, it could herald good or bad things, perfect for doom cults.

Another idea is to use it as free space elevator. Put everything you want in space while moon is close, wait some time till it's higher and release your stuff, basically free lift. Higher eccentricity the better.

EDIT: Also, tides would be much bigger, given moon it bigger then our and/or closer to planet.

  • $\begingroup$ It's actually going to be a "New found world" so pre-existing religions wouldn;t exist. BUT one of the main threads of the story is how religion would adapt or react to this new world. I've been talking to some friends of mine who are Pagans and this would be a lovely move to mirror the more... orthodox. $\endgroup$
    – Tommy
    Dec 20, 2019 at 14:54
  • $\begingroup$ I don't think you can get a free boost from a moon in an elliptical orbit like this. For a start, matching orbits with it at its periapse will be hard, because it will be travelling a lot faster than something in a circular orbit at the same altitude. The amount of effort you have to put into matching orbits with it is exactly the same as if you wanted to just boost your apoapsis to the same distant point. You might be able to do some nifty gravity boost manoevers, but you'll still have had to boost a your spacecraft into orbit, and that is far from cheap. $\endgroup$ Dec 20, 2019 at 20:34

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