Awoken by a random thought in the middle of the night. That and I have to get up to go pee. What would have happened if the Earth spun in the opposite direction, i.e., the sun came up in the west, but everything else was the same. Would this affect weather patterns, ocean currents, plate tectonics, etc.? If so, how would that have affected the development of human civilizations?
I really need to go back to bed. I have to get up early to go to work. I’ll let you guys work on this for me.
Coriolis forces would cause hurricanes to rotate in the opposite direction to what we consider normal; the same coriolis forces also apply to the molten parts of the earth below us, so are probably responsible in some part for the shaping of continental plates and such, so the world would certainly look different to the way it does, but there’s a lot of randomness in the mix too, so if you started with two identical earths rotating in the same direction, you would get two different configurations of continents anyway.
If a powerful wizard reversed the rotation of the earth tonight (and the magic spell took care of inertia so we didn’t all just die as a result of the immediate phenomena of the reversal), then things would get interesting, in probably bad ways - reversal of the direction of tides would create tidal bores in some rivers that don’t currently have them (so lots of flooding). A lot of coasts and islands where there is a soft sandy part trailing a durable rocky part, would suffer significant tidal erosion with the tides going the wrong way.
Oh, and that new sundial you bought? Useless.
Possibly North America would have been discovered by Europeans before South America, rather than the other way around. The North Atlantic is dominated by the trade wind system which has winds going east-to-west in lower latitudes and west-to-east in higher latitudes. In your scenario, this would be reversed, which would probably have taken the first navigators to cross the Atlantic further north.
Nothing else would be the same.
Would this affect:
weather patterns: yes, profoundly
ocean currents: yes, profoundly
plate tectonics: less sure of extent, but probably as profoundly
The Gulf streams would rotate anticlockwise. The US get’s colder/drier, Europe/Africa get hotter/wetter
That big rain shadow region you have stateside caused by the Rockies wouldn’t be there even assuming the Cocos Plate bumped into the North American plate rather than Eurasian Plate.
If mankind had evolved in Africa, where they evolved/migrated would likely be in the other direction as East Africa would be equatorial and West Africa would be savannahs … which assumes the rivers run in the same directions.
Gawd knows whether the Indian sub-continent and the monsoonal weather engine of the Himalyas bumps into the bottom of South Africa and creates a landbridge to Antarctica which blocks global circulation of ocean current et al … and the Rift Valley is pushed up into a mountain range, rather than be torn into … well a rift.
In a thread a long time ago, I opined that the Coriolis effect was almost certainly responsible for the higher salinity on the east side of Chesapeake Bay: fresh river water flowing south tends to hug the west side of the bay while saline ocean tides flowing north stick to the east side of the bay. Spin the earth backwards, and this will be reversed. I expect this would cause the ecosystems on each side of the bay to swap places, perhaps affecting human settlement and seafaring economic activity. The same is likely true for other places around the world where rivers flow north or south into the sea.
The Coriolis force has a negligible effect on plate tectonics.
I’m sure we’ve had thread(s) on this before, but it’s been a few years. I just spent a few minutes searching fruitlessly. Whatever the thread was, the title wasn’t obvious.
Anyone else remember this or care to take a stab at finding it?
Related question: I read some time ago, probably in a science fiction book, that Earth’s planetary magnetism is due to Earth’s molten core and planetary rotation. 1) Is that correct? 2) If the Earth spun in the opposite direction would the magnetic “North” pole be in the continent we call Antarctica?
@Wrenching_Spanners two above …
#1 is correct. But #2 is not.
The direction of the Earth’s magnetic field swaps every few hundred thousand years after a few thousand years of just being a meandering confused mess, not the nice neat situation we see in diagrams in books where all the field lines emerge from one spot near one geographic pole, flow symmetrically all around the Earth and reenter neatly at a spot on the opposite side near the opposite geographical pole.
Naming the magnetic poles “north” and “south” was in that sense a mistake. They should have chosen other terms, like positive or negative.
See for more:
That’s certainly one of them, if maybe not the one I was thinking of. Good find.
I did not post in that thread. I am pretty sure I’d posted in the one I was thinking of. Which also explains why I didn’t find the one you found. I had restricted my search to threads I’d posted to.
Oh, well, then, this?
That’s the one I remember posting to. Thank you.
De nada!
The other main effect would be the Gulf Stream not streaming. It flows, thank to Mr. Coriolis, northeast to Iceland and northern Europe. This produces a moderate climate for much of northern Europe, and a passable climate in Iceland which is at the same level as much of Grreenland and Canada’s frozen north.
If we suggest a reverse flow, it woud come from the Spanish and northwest African coast (Morocco etc.) and warm Labrador and southern Greenland, making them much more inhabitable. It might be less of an effect, since the area of origin is less likely to produce as much hot water. As I understand the secret superpower of the Gulf Stream is that it originates in the much shallower Gulf and Carribean to get much warmer (and feed all those hurricanes). It would be an interesting speculation what the resulting climate is if there’s no natural major outflow from that area. Would hurricane storms instead all spawn locally, then travel the opposite direction and innundate inland Texas and New Mexico? Hitting the Rockies, they would drop inordinate amounts of rain.
Would the focus of the monsoons be instead northwest from the Indian ocean, with tropical storms innundating the Middle East instead of Bangladesh and Myanmar?
In fact - in the real world - with the returning flow added too the Gulf Stream makes up the Atlantic Meridional Overturning Circulation (AMOC). There’s a fear that excessive melt from Greenland could produce a flow of cold fresh(er) water coming down between Labrador and Greenland that could interfere and turn off this Gulf Stream flow and result in a much cooler Europe.
We’d have to get a new phrase to go with “Is the Pope Catholic?” and, “Does a bear shit in the woods?”
If you click on “related” instead of “suggested” threads, the AI actually gives three threads about this subject.
Wow. Thanks. I’d only considered ordinary text search.
Past time for this fogey to start talkin’ to his devices and start eyeballin’ that consarned newfangled AI stuff. Next you know, folks’ll stop wearing onions on their belt.
It seems like whatever forces caused the Earth to spin in the opposite direction in the first place would have had a profound, or at least constant, effect from the beginning. The question is, can we fill in some details?
Probably the biggest question there is, would the Moon orbit the same way as now, or the opposite?
The Moon currently shifts its rising time later by about an hour every day. If the Earth were to spin in the opposite direction, then the Moon would rise about an hour earlier every day, which would have a big change on the tide schedule. So everything that relies on that schedule would be different, to at least some extent.