Is it true that the earth's rotation is slowing down?

[Masua]

If it is true, could anybody tell me how it is happening?

[Ryan_m_b]

IIRC it's down to the Moon. The Moon slows down the Earth's spin and at the same time this boosts the Moon into a higher orbit.

[iKnighty]

IIRC it's down to the Moon. The Moon slows down the Earth's spin and at the same time this boosts the Moon into a higher orbit.
But using the same argument, isn't the Earth also slowing down the Moon's spin and thus pulling it in to a closer orbit?

[Masua]

But using the same argument, isn't the Earth also slowing down the Moon's spin and thus pulling it in to a closer orbit?

maybe they are trying to reach a state of equilibrium over time.
my thoughts are that it is not going to happen forever, am I right??

[Drakkith]

But using the same argument, isn't the Earth also slowing down the Moon's spin and thus pulling it in to a closer orbit?

Since the Moon is tidally locked now, that means we already slowed it's rotation down almost as far as it can go. As the Moon's orbital period gets longer so does it's day. Also, since the rotation of the Earth is in the direction of the Moons orbit it pushes the tide nearest to the moon forward, meaning that there is now a slight amount of mass ahead of the Moon, applying torque to it. This would speed up the Moons orbit, but that energy is used to extend it further out of the Earth's gravitational pull a little bit. So the result is the Moon gets further away from us and our rotation slows.

[Jimmy]

maybe they are trying to reach a state of equilibrium over time.
my thoughts are that it is not going to happen forever, am I right??

http://en.wikipedia.org/wiki/Tidal_acceleration
If other effects were ignored, tidal acceleration would continue until the rotational period of the Earth matched the orbital period of the Moon. At that time, the Moon would always be overhead of a single fixed place on Earth. Such a situation already exists in the Pluto-Charon system. However, the slowdown of the Earth's rotation is not occurring fast enough for the rotation to lengthen to a month before other effects make this irrelevant: About 2.1 billion years from now, the continual increase of the Sun's radiation will cause the Earth's oceans to vaporize, removing the bulk of the tidal friction and acceleration. Even without this, the slowdown to a month-long day would still not have been completed by 4.5 billion years from now when the Sun will evolve into a red giant and likely destroy both the Earth and Moon.

[Radrook]

If it is true, could anybody tell me how it is happening?


We can compare the situation between earth and our moon to a merry go round and a rider on a horse circling it in the same direction on a track.

Let's say that the merry go round is earth and the horse and rider are the moon.

The rider has a lasso = gravity

If he lassoes one of the merry go round's horses he will gain speed.
Conversely the merry go round will experience drag and will lose velocity.

Another way that earth rotation is slowed is via the friction of currents on the ocean floor which have a braking effect..