Has this ever happened in earth history, or can it ever happen? Can the sun ever rise from west? What i mean is can the world start to turn the opposite direction and let the sun rise from west? Is it possible?

Yes, it is possible. It happened to Venus too. But you'd have to wait a couple of billion years.

The earth's axis would have to spin ~180 degrees.
Or reverse direction in orbit, but we know that's not gonna happen.

The earth's axis would have to spin ~180 degrees.
Or reverse direction in orbit, but we know that's not gonna happen.

Still the sun will rise from east, in both the cases.

The earth has to reverse its direction of rotation about its own axis.

No, my first statement was correct. If the axis of rotation were to rotate 180 degrees in a plane perpendicular to the direction of the sun, it would rise on the opposite side.

I insist.

This could happen to Earth too.

The moon recedes with some inch or so a year, whilst the Earth is slowing down. Both cause the frequency the precession of the equinoxes to decrease (now 26,000 years). As soon as this frequency approaches the frequency of the obliquity cycle (now 41,000 years) resonance will occur, causing extreme shifts in obliquity, known as the chaotic zone

Correia and Laskar have calculated the possible spinning history of Venus and theorize that either the spin axis of Venus toppled causing the retrograde spin or the differential gravity interaction of the dense atmosphere with the sun caused it.

http://astro.oal.ul.pt/~acorreia/cvpubs/venus1.pdf

I insist.
This could happen to Earth too.No one said otherwise.

Alpha,
In both positions, for example, America comes after Africa to see the Sun on horizon. The hands of a watch always run clock-wise (1 before 2 before 3..) even if you keep the the watch face down.

locked

Alpha,
In both positions, for example, America comes after Africa to see the Sun on horizon. The hands of a watch always run clock-wise (1 before 2 before 3..) even if you keep the the watch face down.Er, my mistake.
I suppose it would have to spin in the opposite direction after all.

Is it possible for a really major asteroid - or a nasty comet - strike to reverse the spin of a planet? Now. Let's imagine Shoemaker-Levy II smashing right against the equatorial spin of Earth... Whoa :eek:

I think so, though I don't believe any life on earth would survive an impact of the necessary magnitude.

If I may have a different opinion, I'm afraid there are a few complications. If you drop a mouse from ten feet hight, it just runs away. If you drop an elephant of ten feet, it will break it's legs and a lot more. It probably dies on the spot.

Earth is a tremendous elephant in that respect. It's not a game of marbles (mice). If you hit one side of the Earth with an asteroid, big enough to change the spinning speed, that side will start decellerating. However due to it's size, the shock wave will take ninety minutes before it reaches the opposite site of the world. So, since that part just continues spinning fat dumb and happy while the opposite side stopped, the result is an Earth torn to pieces. All what's left is another asteroid belt.

Yes i agree a asteroid big enough to change earths rotation would be powerful enough to shatter this planet into nothing but pieces. And walla another asteroid belt or gravity pulls the planet back together and walla a lifeless dead planet like all the others.

yep, the earths mass is something like 6.0 x 1024kg and spins 1670 km/hr (at the equator). I haven't done the math but based on those numbers I'm pretty sure it would take a world shattering event to even slow it down let alone reverse the spin.

I feared as much. I was sure life wouldn't survive, but not sure if the planet would or not.

it can rise from the west but not the other side.

just wait for the next flip of earth poles, as far as compasses are concerned north will be south and east will be west

just wait for the next flip of earth poles, as far as compasses are concerned north will be south and east will be west

that's cheating though, you'd still be looking the same direction at sunset and sunrise. Only the names of the directions you were looking would have changed.

As far as actually changing the earth's spin, the more I think about it, the more disasterous I think it would be. If you could reverse the spin (by some unknown method that wouldn't destroy the planet) what about the oceans, the molten core and the atmosphere, wouldn't they keep spinning the wrong way for a while? I can't imagine what the result would be but I'm pretty sure it would be very, very bad. Tidal waves, earth scouring wind speeds and volcanoes popping their lids across the planet at the very least.

The atmosphere and the ocean circulation are both heavily tied into the rotation of the planet. If Earth were to reverse it's rotational spin ... then the atmosphere and the ocean circulation would dramatically alter into a new pattern.

The elements of the atmosphere (such as the Trade Winds and weather patterns) would eventually reverse direction along with the new rotational spin of the planet (since momentum would keep it going "the wrong way" for a bit). In essence, any atmospheric patterns we see today would only reverse direction in the new spin of the planet. This picture shows what the major large-scale wind systems of the planet are now:

http://nsidc.org/arcticmet/images/factors/global_circulation.gif

To imagine what would happen to those patterns if the planet would reverse its spin, just reverse the direction of those arrows (left to right and right to left). The curvature of the winds is due to the Coriolis force

However, the ocean circulation wouldn't be so compelled to reverse direction as easily. Any reversal in the spin of the planet would completely collapse the ocean current circulation and eventually form a new pattern which could completely alter climate conditions all over the planet. For example, Canada and Europe would no longer get it's warm water from the Gulf.

Even though both are basically the same system ... it's the oceans which practically controls atmospheric phenomenas such as the weather.

eventually I'm sure they would settle into a new pattern (though I suspect it'd be more complex than a simple reversal of those arrows) but before everything was settled there would be serious problems.

The atmosphere would suddenly be moving over the planet at atleast twice normal speed. Suddenly the continents would find themselves litterally burying themselves into oceans that haven't yet realised they're going in the wrong direction. And since the crust is floating on a spinning liquid core, if the crust just started moving against that internal spin it would... well I have no idea what it would do but I imagine it would mean earthquakes and volcanoes of hitherto unknown magnitudes.

Well, to add to the general confusion, if the Earth would flip over, the way Venus may have done, or alternately, come to a spinning stop eventually and then reversing the spin slightly, then the Earth would get all the other characteristics of Venus as well, that is a scorning inferno of a 1000 degrees temperature, volcanoes all over the place and about a 90 bar carbon dioxide atmosphere.

It's a package deal, you know. Buy one, get all. Where else do you leave all than energy from loosing all that spinning. Earth just would become a big hot brake.

well, I hate to speak for everyone but I think we have reached a general consensus here. I believe we can safely say:

If, for whatever reason, the world suddenly reversed it's spin... it would be bad, really, really bad.

Right, now we have to wait a couple of billion years for those "whatever reasons", the chaotic zone:

http://aa.springer.de/papers/7318003/2300975/sc1.htm

Originally posted by buffys
eventually I'm sure they would settle into a new pattern (though I suspect it'd be more complex than a simple reversal of those arrows) but before everything was settled there would be serious problems.

The atmosphere would suddenly be moving over the planet at atleast twice normal speed. Suddenly the continents would find themselves litterally burying themselves into oceans that haven't yet realised they're going in the wrong direction.

This was something I forgot to mention while posting at 1 in the morning. Yes ... the atmosphere would be moving "twice" as fast across the planet after the reversal until it stops and reverses direction itself ... but that's assuming the planet attains the same rotational speed as before (except negative). Between the time the planet starts to reverse its spin and the stabilization of the atmosphere to adjust to the new rotation of the planet, the atmospheric patterns would be in complete chaos as it tries to sort itself. It would look like a car wreck. And the stabilization process is not something that will happen overnight. It will take thousands of years for the atmosphere to reverse direction completely and during that time period, weather patterns and such would be devestating to the planet.

However, it would eventually stabilize into a new pattern that would resemble the picture I posted except with the arrows reversed. But keep in mind that the pic talks about large scale wind systems ... it will be as simple as a reversal of those arrows because that is how the atmosphere behaves on this planet.