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Encyclopedia entry: Earth tides
- Article from:
- The Oxford Companion to the Earth
- Author:
Copyright© The Oxford Companion to the Earth 2000, originally published by Oxford University Press 2000. (Hide copyright information)
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Earth tides
The gravitational attraction between the Earth and Moon keeps them in orbit about their common centre of mass, which is a point within the Earth 4670 km from the centre. Both the Earth and the Moon are nearly spherical, which means that the total attractive force between them is nearly the same as if they were point masses at their centres. Thus the centripetal force on each is just that required to keep point masses at their centres in orbit about one another. The side of the Earth nearer to the Moon experiences a stronger gravitational pull than is needed to keep it in orbit with the rest of the Earth. It is therefore pulled towards the Moon. Conversely, on the far side of ...