The setting is Earth with the ordinary moon moving as per usual, but this planet also has a moon with stronger tidal pull that moves in an elliptical orbit and comes to its closest point to Earth every fourth year.

How would this impact oceanic currents? Would the stronger moon pull them out of their usual pattern when it is on its closest point?

Central to this question is the elliptical orbit of the moon with the stronger pull and the time it uses between reaching it's closest point. Similar questions only asking about two earthlike moons do therefor not answer my question.

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    $\begingroup$ I am strongly tempted to close this question as a duplicate of this one: worldbuilding.stackexchange.com/questions/66290/… @Martine what do you think? Does that question answer yours or should yours stay open on its own? $\endgroup$
    – SRM
    Feb 5, 2017 at 14:25
  • $\begingroup$ How elliptical is your orbit? Got any figures for your point of closet approach? Are we to ignore any feasibility in terms of keeping the ordinary moon orbit the same and just accept that it does? $\endgroup$ Feb 5, 2017 at 14:29
  • $\begingroup$ I've edited my question to explain why this is not a duplicate. @SRM $\endgroup$ Feb 5, 2017 at 15:19
  • $\begingroup$ @LioElbammalf you ask good questions here, I'm off to a meeting now, but I'll be back later to adress them. $\endgroup$ Feb 5, 2017 at 15:21
  • $\begingroup$ After having thought about this for a while I'm a bit tempted to answer my own question and explain why this scenario is highly unlikely to be stable over the time. :/ ah, some ideas are so good before you actually think them through. But I'm not sure I would have been thinking as critically about it as I did if I hadn't posted it here, so I'm glad I did. $\endgroup$ Feb 6, 2017 at 16:28

1 Answer 1


Orbits of large objects always seem to be nearly circular. It's just the way they form. So this scenario is unrealistic.

Different size and orbit of a moon gives tides of different height and frequency, and tides influence the oceanic currents, strongly. If the tide heighs vary more strongly over a month than they do on earth, then, yes, that obviously also influences the oceanic currents. It could surely be predicted by simulations.

  • $\begingroup$ One little but important thing: this is a chaotic situation, so analytical solution is next to impossible, and numerical one can give errors, too. $\endgroup$
    – Mołot
    Feb 6, 2017 at 8:26

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