Re: What would happen if the earth revolved in the opposite directions?

Hi, Deb,
This is an interesting question, and it is a little more complicated that it appears. The actual possibility that this would happen is very, very small, for all purposes it is zero. It is true that the earth's rotation rate is slowing , due to tidal forces from the Moon. However the rate is so small that the Sun will enter its red giant phase before then, and the earth could be engulfed by the expanding Sun.

The obvious consequence of a reversed rotation is that the Sun would rise in the west and set in the east. Now with that out of the way, let's look at other effects. First, the slowing of the rotation would have to be over a very long time, billions of years would be the best. If the rotation were to stop suddenly, everything that wasn't tied down would keep going according to Newton's first law; bodies in motion tend to remain in motion. The rate at which the Earth slows would determine how much stuff would keep going.

Let's say that the Earth slows over billions of years so as not do destroy everything. What types of things are dependent on the rotation of the Earth? The obvious is the diurnal cycle of day and night. The Moon's rotation is such that it takes the same length of time for it to revolve around the Earth as it does to rotate once. For the Earth this would mean that our year and day would be equal, and we would have the same face toward the Sun all the time. This would dramatically affect climate and weather. Life would have to alter in order to survive. Another thing that would happen as the Earth slowed would be the diminishing of the magnetic field. The Earth's magnetic field is created by the rotation of the Earth and its core. As the magnetic field decreases the Van Allen radiation belts that protect the Earth from harmful radiation from the Sun would disappear. This would mean an end to the aurorae and a significant increase in the amount of destructive radiation reaching the surface of the Earth. There are some indications that the loss of a magnetic field could also mean an end to our atmosphere as the increased radiation scours the lighter molecules and the water vapor in the air away.

If we survive all that and the rotation reversed, although I don't see any normal physical means for this to happen outside a direct impact by a planetary sized object from space and that would pretty much mean an end to the Earth as we know it. The reversed direction of rotation would mean that a magnetic field could be regenerated. If we didn't lose the water and lighter gasses during the period without a magnetic field, then life would still be possible although probably very different. Once we get to this point, the Eun would rise in the west and set in the east, if there were any creatures around to see it.