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
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 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 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.
:smack: Thank you.
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.
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.
Did he mention why satellite images have consistently failed to record this?
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.
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.
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.
Obviously, that’s because they’re really connected every 12 hours. 
Good catch. My argument lies in tatters. 
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
Time would go backwards
An impact is not required in theories by people who study such things. Two examples of papers about the rotation of Venus:
Note this line in the first abstract:
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.
A popular theory is that the Earth was impacted quite early (about 100 M years after formation) by a big object 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.
Just a nitpick, but the 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.
The Wiki site has this to say:
I look forward to this event with great expectation and lots of popcorn.
Note that in this documentary, 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.
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?
According to that logic, my clock’s hands could never move, because if I view it from behind, the hands move counter-clockwise.