Astronomy: General

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tidal friction

A Dictionary of Astronomy | 1997 | Copyright

tidal friction A force between the oceans of Earth and the ocean floors caused by the gravitational attraction of the Moon. The Earth tries to carry the ocean waters round with it, while the Moon tries to keep them heaped up under it and on the far side of the Earth (see tides). Over long periods of time tidal friction decreases the Earth's rate of spin, so lengthening the day. In turn, the Moon has angular momentum added to it in its orbit and gradually spirals away from Earth. Ultimately, when the day equals the Moon's orbital period (each being about 40 times the length of the present day) the process will cease. A new process will then begin in which the Sun's tide-raising power takes angular momentum from the Earth–Moon system. The Moon will then spiral in closer to the Earth until it is torn to pieces when it enters the Earth's Roche limit.

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tidal friction

A Dictionary of Earth Sciences | 1999 | | Copyright

tidal friction The friction exerted on the Earth because of the phase lag between the tides and the gravitational attraction of the Moon, Sun, and planets. It is mostly due to the M₂ ocean tide (M₂ is the principal component of the forces acting in the direction of the Moon). See also DAYLENGTH.

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AILSA ALLABY and MICHAEL ALLABY. "tidal friction." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>.

AILSA ALLABY and MICHAEL ALLABY. "tidal friction." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O13-tidalfriction.html

AILSA ALLABY and MICHAEL ALLABY. "tidal friction." A Dictionary of Earth Sciences. 1999. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-tidalfriction.html

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