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Right, I saw a question about why the Earth spins counter clockwise, and it reminded me of something I would like to know the answer to.

I watched a episode of Futurama. In this episode the Earth stops spinning and they restart the Earth's spin, but going the other way (clockwise).

Would the Earth function in the same way if this was possible to do? What effects could this have?

Note: I'm not even 100% what way we are spinning - it depends how you look at it, right?

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    $\begingroup$ Ah yes, That Darn Katz!. BTW, the convention is that Earth spins counter clockwise (looking down on the North Pole). As mentioned by others, wind directions would change, with local climatic differences, but otherwise life would go on. $\endgroup$
    – Phil Perry
    May 1, 2014 at 13:27
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    $\begingroup$ Here is an (open access) article where they ran that planet in a climate model. V. Kamphuis, S. E. Huisman, and H. A. Dijkstra: The global ocean circulation on a retrograde rotating earth, dx.doi.org/10.5194/cp-7-487-2011 $\endgroup$
    – flo
    Sep 23, 2014 at 19:21

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That would have many consequences. For example the Coriolis force would change the sign. Thus wind around pressure systems would switch the direction from north and south hemisphere, but also the Ekman spiral in the ocean would be affected. Surface heating at sloped terrain will different, as the sun would rise in the West. This would change thermal induced circulations. And the conservation of angular momentum is important for the general circulation.

I would expect major impacts on the resulting climate, even in an equilibrium mode, which does not account for the acceleration to the oppose rotation velocity.

During the time of stopped rotation additional circulation systems can be expected, which exchange energy between the day and the night side of the earth.

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  • $\begingroup$ Ah, very interesting! Thank you for your answer. $\endgroup$
    – Ruddy
    May 1, 2014 at 21:14
  • $\begingroup$ I would be most interested to see the transition in the atmosphere before things equlibrate to the change. I've seen what happens in rotating tank experiments where you just stop the rotation, but to reverse must be even more interesting (and terrible). $\endgroup$
    – casey
    May 2, 2014 at 2:47
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    $\begingroup$ @casey I would be very interested to this transition, but from a distance. If you decide to try this out, please use a spare planet rather than this one ;-) $\endgroup$
    – Semidiurnal Simon
    May 4, 2014 at 11:42
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    $\begingroup$ There would be a bunch of other knock-on effects from switching the wind direction - for instance, there is a pattern of desertification on the western side of continents at mid latitudes. Presumably that would switch to the Eastern side. $\endgroup$
    – naught101
    May 5, 2014 at 3:11
  • $\begingroup$ @BHF Should that be maJor impacts? $\endgroup$
    – Michael Mior
    Oct 6, 2014 at 17:10
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Depending on the assumptions you make, the Moon would suddenly have a retrograde orbit. If the moon had a retrograde orbit, it would have tremendous consequences. Retrograde orbits tend to become less distant over time, meaning the moon would either be much closer to the Earth with huge tidal effects or come more close in the future. At some point, the Moon would or would have passed the Earth's Roche limit, break up, and create a temporary ring system which would shower the Earth with impacts.

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    $\begingroup$ Why do retrograde orbits become less distant? Tidal effects? $\endgroup$
    – gerrit ♦
    May 1, 2014 at 14:41
  • $\begingroup$ Yes. See en.wikipedia.org/wiki/Orbital_decay#Tidal_effects $\endgroup$
    – DCKing
    May 1, 2014 at 14:46
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    $\begingroup$ Oh, very good point! Even ignoring the dumping-the-moon-on-our-heads aspect (which would take a long time, I suspect), if one were to reverse the earth's rotation without changing the direction of the moon's orbit then that would change the length of the lunar day, and plenty of other periods that are important for tidal mechanics; so in addition to the earth's tides being very different due to reverse Coriolis, they'd be even more different thanks to altered periods, and thus different resonances. $\endgroup$
    – Semidiurnal Simon
    May 4, 2014 at 11:45
  • $\begingroup$ Many species use the moon for timing and might have trouble adapting their phenology, too. $\endgroup$
    – cphlewis
    Apr 2, 2015 at 23:56

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