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Home  Education  Tides and Water Levels  What Causes Tides?
  << Back The relationship  between the masses of the Earth, moon and sun and their distances to  each other play a critical role in affecting the Earth's tides. Although the sun is 27 million times more massive than the moon, it is 390 times further away from the Earth than the moon. Tidal generating  forces vary inversely as the cube of the distance from the  tide-generating object. This means that the sun’s tidal generating  force is reduced by 3903 (about 59 million times) compared  to the tide-generating force of the moon. Therefore, the sun’s  tide-generating force is about half that of the moon, and the moon is the dominant force affecting the Earth’s tides.


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