# What If The Earth Spun The Other Way **URL:** \ **Category:** Factual Questions\ **Created:** [November 8, 2008, 9:23pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844 "2008-11-08T21:23:02Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![BigBertha](https://avatars.discourse-cdn.com/v4/letter/b/d78d45/32.png) [@BigBertha](https://boards.straightdope.com/u/BigBertha)\ **Post date:** [November 9, 2008, 7:39pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/21 "2008-11-09T19:39:11Z")
Stopped rotating but kept revolving around the sun. How would that affect winds? ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [November 9, 2008, 7:52pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/22 "2008-11-09T19:52:02Z")
> [@Tamara+](#): > > Stopped rotating but kept revolving around the sun. How would that affect winds? One side of the planet would get really cold, and one side would get really hot. Around the terminator a hellacious storm would rage as hot air from the sun side pushes over the cold air from the dark side, cools and falls. Really, really unpleasant, but not as unpleasant as freezing to death in the dark side. Of course, over the course of a year the sun exposed portion of the planet would move, so I suspect that the situation would be inimical to continued survival of life. Si ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [November 9, 2008, 9:02pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/23 "2008-11-09T21:02:50Z")
> [@Markxxx](#): > > could something in theory change the way the Earth spins? Like if an asteroid hit it, could it cause the Earth to rotate the other way Yes, but not one of the asteroids we have now. Most planets in the Solar System rotate in the same direction that they revolve around the Sun, but not all do. Venus rotates backwards. A popular theory is that Venus’ retrograde rotation is due to a giant impact in the early history of the Solar System. If it happened to Venus, there’s no reason it couldn’t have happened to Earth as well. It couldn’t happen now, though. At that point in the Solar System’s history, there were objects the size of Mars (possibly bigger) on orbits that crossed the orbits of others. There aren’t any of those around now. Earth-crossing asteroids are small- generally a few tens of meters or a few kilometers in diameter. Those aren’t big enough to affect the Earth’s rotation. Even the hypothetical 500-km Earth-crossing asteroid we discussed [in another thread](http://boards.straightdope.com/sdmb/showthread.php?t=489931) wouldn’t be big enough to affect Earth’s rotation, if it existed (which it doesn’t). There’s nothing anywhere near big enough in an Earth-crossing orbit now. The Moon probably wouldn’t still be there. I explained in [this thread](http://boards.straightdope.com/sdmb/showthread.php?t=491526) why the Moon’s orbit is moving farther away from Earth. If the Earth rotated the other way but the Moon still went around the Earth the same way it does now, the nearer tidal bulge would be pulling back on the Moon in its orbit, and it would eventually crash into the Earth. This is generally true for moons in retrograde orbits- Phobos, which is in a retrograde orbit, is going to crash into Mars in a few tens of millions of years, for example. I’m not sure how long it would have taken for the Moon to crash into the Earth if the Earth rotated the other way, though. If the Moon crashed into the Earth after life had developed, that wouldn’t be good for life. I’m not sure at what speed it would come in, but the likelihood is that the impact would be enough to boil Earth’s oceans. That would wipe out all life except for maybe bacteria and thermophiles. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 9, 2008, 9:50pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/24 "2008-11-09T21:50:27Z")
> [@Chez\_Guevara](#): > > Fixed [**Mangetout** ’s link](http://boards.straightdope.com/sdmb/showthread.php?t=140878). :smack: Thank you. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [November 9, 2008, 10:26pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/25 "2008-11-09T22:26:51Z")
> [@Anne Neville](#): > > The Moon probably wouldn’t still be there. I explained in this thread why the Moon’s orbit is moving farther away from Earth. If the Earth rotated the other way but the Moon still went around the Earth the same way it does now, the nearer tidal bulge would be pulling back on the Moon in its orbit, and it would eventually crash into the Earth. This is generally true for moons in retrograde orbits- Phobos, which is in a retrograde orbit, is going to crash into Mars in a few tens of millions of years, for example. I’m not sure how long it would have taken for the Moon to crash into the Earth if the Earth rotated the other way, though. We could flip the Earth over, North for South, _and_ spin it backwards. Then the South pole would point towards Polaris, and the Sun would rise in what’s now the West, but the Earth’s rotation and the Moon’s revolution are now in the same direction, so the Moon will recede from the Earth as it does now. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 9, 2008, 10:57pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/26 "2008-11-09T22:57:09Z")
To experience the Earth spinning the other way, it is only necessary to visit the opposite hemisphere (the southern one, for most readers, I suspect). Of course that viewpoint also means the earth is orbiting the sun the other way too. There’s a guy (by which I mean _nutcase_) out there somewhere on the web who was claiming that nobody could cross the equator because Earth’s two hemispheres were independently rotating in opposite directions (stand on the North pole and the Earth is rotating anticlockwise under you, on the South pole, it’s clockwise). The Time Cube guy mentions something like this in passing, but nowhere near the detail of the guy I’m remembering. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [November 9, 2008, 10:59pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/27 "2008-11-09T22:59:58Z")
> [@Mangetout](#): > > There’s a guy (by which I mean _nutcase_) out there somewhere on the web who was claiming that nobody could cross the equator because Earth’s two hemispheres were independently rotating in opposite directions. Did he mention why satellite images have consistently failed to record this? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 9, 2008, 11:04pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/28 "2008-11-09T23:04:42Z")
I don’t think he believed in satellites. More puzzling is how he overlooked the fact that ocean vessels failed to record it, and how the poor folks in Brazil or Kenya coped with only being connected to the other half of their country briefly every 24 hours. ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [November 9, 2008, 11:12pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/29 "2008-11-09T23:12:10Z")
If the Moon had crashed into the Earth, that would probably wipe out any life that was there before the crash. That of course doesn’t mean life couldn’t originate again. We might have more mass extinction events if the Moon weren’t there. There’s a theory that the Moon reduces the number of those impacts, because some objects that would otherwise have hit the Earth hit the Moon instead. > [@Mangetout](#): > > To experience the Earth spinning the other way, it is only necessary to visit the opposite hemisphere (the southern one, for most readers, I suspect). That’s true. The Moon and all the constellations look upside down from there. When I visited Australia a few years ago, the moon looked upside down compared to what I was used to. I was leaning my head way over to one side to make it look normal- I almost fell into Sydney Harbor. But the Sun does still rise in the east and set in the west there. I think weather systems generally move from west to east at that latitude, too. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [November 9, 2008, 11:12pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/30 "2008-11-09T23:12:31Z")
> [@Mangetout](#): > > …how the poor folks in Brazil or Kenya coped with only being connected to the other half of their country briefly every 24 hours. Obviously, that’s because they’re really connected every 12 hours. 😛 ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 9, 2008, 11:25pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/31 "2008-11-09T23:25:48Z")
Good catch. My argument lies in tatters. 😉 ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [November 10, 2008, 7:36am UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/32 "2008-11-10T07:36:16Z")
> [@Anne\_Neville](#): > > When I visited Australia a few years ago, the moon looked upside down compared to what I was used to. I was leaning my head way over to one side to make it look normal- I almost fell into Sydney Harbor. That was just the **XXXX**. 😉 How much of the large scale weather effects (jet streams, etc) are driven by the direction of earths physical rotation vs those driven by the effect of solar heating on the atmosphere as day follows night. Because changing the nature of that relationship may introduce more and stronger interactions. Si ---
**Author:** ![Bearflag70](https://avatars.discourse-cdn.com/v4/letter/b/8e7dd6/32.png) [@Bearflag70](https://boards.straightdope.com/u/Bearflag70)\ **Post date:** [November 10, 2008, 7:44am UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/33 "2008-11-10T07:44:49Z")
Time would go backwards ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [November 10, 2008, 9:32am UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/34 "2008-11-10T09:32:26Z")
> [@Anne\_Neville](#): > > Yes, but not one of the asteroids we have now. Most planets in the Solar System rotate in the same direction that they revolve around the Sun, but not all do. Venus rotates backwards. A popular theory is that Venus’ retrograde rotation is due to a giant impact in the early history of the Solar System. An impact is not required in theories by people who study such things. Two examples of papers about the rotation of Venus: [paper 1](http://www.nature.com/nature/journal/v275/n5675/abs/275037a0.html) [paper 2](http://cat.inist.fr/?aModele=afficheN&cpsidt=17367351) Note this line in the first abstract: > [@](#): > > Tides raised by the Sun in the body of Venus would de-spin the planet in ~10[sup]8[/sup] yr if no other torques were acting. It doesn’t matter if the planet were originally going pro- or retrograde, by now the original spin has long been erased. Now they seem to be arguing over what keeps it from being tidally locked to the Sun. > [@](#): > > If it happened to Venus, there’s no reason it couldn’t have happened to Earth as well. A popular theory is that the Earth was impacted quite early (about 100 M years after formation) by a [big object](http://en.wikipedia.org/wiki/Giant_impact_hypothesis) that formed the moon. If the Earth had been rotating retrograde when Theia hit, no doubt the result of that impact would have been significantly different. Perhaps the moon would not have formed. Or have formed with a different orbit, perhaps even a retrograde one. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [November 10, 2008, 1:24pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/35 "2008-11-10T13:24:09Z")
> [@Anne\_Neville](#): > > Phobos, which is in a retrograde orbit, is going to crash into Mars in a few tens of millions of years, for example. Just a nitpick, but the [Roche Limit](http://en.wikipedia.org/wiki/Roche_limit) will intervene first and break up the moon into little moonly bits before that happens. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [November 10, 2008, 2:53pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/36 "2008-11-10T14:53:53Z")
> [@Musicat](#): > > Just a nitpick, but the [Roche Limit](http://en.wikipedia.org/wiki/Roche_limit) will intervene first and break up the moon into little moonly bits before that happens. I think Phobos is too small for that to be an issue. At only 22 km, it’s small enough to be held together primarily by electromagnetic forces, rather than gravity. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [November 10, 2008, 3:47pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/37 "2008-11-10T15:47:56Z")
> [@Q.E.D](#): > > I think Phobos is too small for that to be an issue. At only 22 km, it’s small enough to be held together primarily by electromagnetic forces, rather than gravity. The [Wiki site](http://en.wikipedia.org/wiki/Phobos_(moon)) has this to say: > [@](#): > > Phobos’ low orbit means that it will eventually be destroyed: tidal forces are lowering its orbit, currently at the rate of about 20 meters per century, and in 11 million years it will either impact the surface of Mars or (more likely) break up into a planetary ring. Given Phobos’ irregular shape and assuming that it is a pile of rubble (specifically a Mohr-Coulomb body), it has been calculated that Phobos is currently stable with respect to tidal forces. But it is estimated that Phobos will pass the Roche Limit for a rubble pile when its orbital radius drops by a little over 2,000 km to about 7,100 km. At this distance Phobos will likely begin to break up forming a short lived ring system around Mars. The rings themselves will then continue to spiral slowly into Mars. I look forward to this event with great expectation and lots of popcorn. ---
**Author:** ![groo](https://avatars.discourse-cdn.com/v4/letter/g/ecd19e/32.png) [@groo](https://boards.straightdope.com/u/groo)\ **Post date:** [November 10, 2008, 4:30pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/38 "2008-11-10T16:30:46Z")
> [@si\_blakely](#): > > One side of the planet would get really cold, and one side would get really hot. Around the terminator a hellacious storm would rage as hot air from the sun side pushes over the cold air from the dark side, cools and falls. Really, really unpleasant, but not as unpleasant as freezing to death in the dark side. > > Of course, over the course of a year the sun exposed portion of the planet would move, so I suspect that the situation would be inimical to continued survival of life. > > Si Note that in [this documentary](http://www.imdb.com/title/tt0298814/), they showed how it’s possible to use strategically placed nukes throughout the liquid hot magma of the earth’s core to inject enough angular momentum that it can resume its rotation. Presumably, we could just use a little more energy to stop the rotation and subsequently start it back up in the opposite direction. We should be able to test this theory in just a few days, but we’d have to get more than $100 billion (2003 dollars) of unobtanium which, obviously, we won’t be able to do until we get the economy back in shape. ---
**Author:** ![Tom\_Tildrum](https://avatars.discourse-cdn.com/v4/letter/t/e95f7d/32.png) [@Tom\_Tildrum](https://boards.straightdope.com/u/Tom_Tildrum)\ **Post date:** [November 10, 2008, 5:06pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/39 "2008-11-10T17:06:13Z")
> [@Mangetout](#): > > There’s a guy (by which I mean _nutcase_) out there somewhere on the web who was claiming that nobody could cross the equator because Earth’s two hemispheres were independently rotating in opposite directions (stand on the North pole and the Earth is rotating anticlockwise under you, on the South pole, it’s clockwise). > The Time Cube guy mentions something like this in passing, but nowhere near the detail of the guy I’m remembering. Maybe this is based on a misunderstanding of the doldrums? I.e., the fact that the prevailing winds in each hemisphere produce a zone at the equator that can be very difficult for a sailing ship to pass through? ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [November 10, 2008, 5:23pm UTC](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844/40 "2008-11-10T17:23:40Z")
> [@Mangetout](#): > > There’s a guy (by which I mean _nutcase_) out there somewhere on the web who was claiming that nobody could cross the equator because Earth’s two hemispheres were independently rotating in opposite directions (stand on the North pole and the Earth is rotating anticlockwise under you, on the South pole, it’s clockwise). According to that logic, my clock’s hands could never move, because if I view it from behind, the hands move counter-clockwise. [Previous page](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844.md?page=1) [Next page](https://boards.straightdope.com/t/what-if-the-earth-spun-the-other-way/471844.md?page=3)