tidal friction

tidal friction

      in astronomy, strain produced in a celestial body (such as the Earth or Moon) that undergoes cyclic variations in gravitational attraction as it orbits, or is orbited by, a second body. Friction occurs between water tides and sea bottoms, particularly where the sea is relatively shallow, or between parts of the solid crust of planet or satellite that move against each other. Tidal friction on the Earth prevents the tidal bulge, which is raised in Earth's seas and crust by the Moon's pull, from staying directly under the Moon. Instead, the bulge is carried out from directly under the Moon by the rotation of the Earth, which spins almost 30 times for every time the Moon revolves in its orbit. The mutual attraction between the Moon and the material in the bulge tends to accelerate the Moon in its orbit, thereby moving the Moon farther from Earth by about three centimetres (1.2 inches) per year, and to slow Earth's daily rotation by a small fraction of a second per year. Millions of years from now these effects may cause the Earth to keep the same face always turned to a distant Moon and to rotate once in a day about 50 times longer than the present one and equal to the month of that time. This condition probably will not be stable, due to the tidal effects of the Sun on the Earth–Moon system.

      That the Moon keeps the same part of its surface always turned toward Earth is attributed to the past effects of tidal friction in the Moon. The theory of tidal friction was first developed mathematically after 1879 by the English astronomer George Darwin (1845–1912), son of the naturalist Charles Darwin.

* * *

Universalium. 2010.

Look at other dictionaries:

  • tidal friction — noun : the frictional effect of the tidal wave especially in shallow waters lengthening the tidal epoch and tending to retard the rotational velocity of the earth and so increase very slowly the length of the day …   Useful english dictionary

  • Tidal acceleration — is an effect of the tidal forces between an orbiting natural satellite ( i.e. a moon), and the planet (called the primary) that it orbits. It causes a gradual recession of a satellite in a prograde orbit away from the primary, and a corresponding …   Wikipedia

  • Tidal force — The tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational acceleration experienced by a large body is not constant across its diameter. One side of the body has greater… …   Wikipedia

  • Tidal Heating —    This is the heating of a satellite s interior caused by gravity induced friction.    As the satellite rotates around a planet, and possibly passes other satellites, the gravity pulls from different angles and changes the planets shape into a… …   The writer's dictionary of science fiction, fantasy, horror and mythology

  • celestial mechanics — the branch of astronomy that deals with the application of the laws of dynamics and Newton s law of gravitation to the motions of heavenly bodies. [1815 25] * * * Branch of astronomy that deals with the mathematical theory of the motions of… …   Universalium

  • Orbit of the Moon — Not to be confused with Lunar orbit in the sense of a selenocentric orbit, that is, an orbit around the Moon The Moon completes its orbit around the Earth in approximately 27.3 days (a sidereal month). The Earth and Moon orbit about their… …   Wikipedia

  • ΔT — This article is about the time difference. For the temperature difference, see psychrometrics. ΔT vs. time from 1657 to 1984[1] ΔT, Delta T, delta T, deltaT, or DT is the time difference obtained by subtracting Universal Time (UT) from… …   Wikipedia

  • Pierre-Simon Laplace — Laplace redirects here. For the city in Louisiana, see LaPlace, Louisiana. For the joint NASA ESA space mission, see Europa Jupiter System Mission. Pierre Simon, marquis de Laplace Pierre Simon Laplace (1749–1827). Posthumous portrait …   Wikipedia

  • David Rubincam — David Perry Rubincam Born February 27, 1947 (1947 02 27) (age 64) …   Wikipedia

  • Post-glacial rebound — A model of present day mass change due to post glacial rebound and the reloading of the ocean basins with seawater. Blue and purple areas indicate rising due to the removal of the ice sheets. Yellow and red areas indicate falling as mantle… …   Wikipedia