Moon Orbit

[Primarygun]

The moon's orbital around the earth is getting larger and larger.

Why does this happen?

[Jacques]

http://en.wikipedia.org/wiki/Tidal_acceleration

the matter of the Earth, in particular the water of the oceans, bulges out along both ends of an axis passing through the centers of the Earth and Moon. The average tidal bulge closely follows the Moon in its orbit, and the Earth rotates under this tidal bulge in just over a day. However, the rotation drags the position of the tidal bulge ahead of the position directly under the Moon. As a consequence, there exists a substantial amount of mass in the bulge that is offset from the line through the centers of the Earth and Moon. Because of this offset, a portion of the gravitational pull between Earth's tidal bulges and the Moon is perpendicular to the Earth-Moon line, i.e. there exists a torque between the Earth and the Moon. This accelerates the Moon in its orbit, and conversely decelerates the rotation of the Earth.

[gonelli]

I read somewhere that after many, many years the rotation of the Earth will we slowed down so much that a one rotation would last for like a month or something like that.

I was wondering that if over millions of years it's been getting slower, then at some stage in the past the roation of the Earth must have been very fast. Does anyone know how fast it may have once gone? Could once roatation (1 day) have been only an hour long?

[Primarygun]

acknowledge for the explanation.

400 million years ago, we have only 22 hours in one sidereal day.