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Why Do High Tides Happen Both on the Side of the Earth Facing Toward and Away from the Moon?

-- | February 2, 2016

Question: During new moon, moon is between earth and sun. The spring tide then occurs. The height of high tide is higher. But on right side of image why is water having high tide. As there is no force pulling water from right side of image. As sun and moon are on left.  — Priyanshu

Answer: You are right in that high tide occurs on the sides of the Earth which face toward and away from the Moon.  This is due to the fact that around the Moon is pulling on the Earth, and the ocean, on the sides facing the Moon.  The Earth compensates for this pulling by bulging out both toward and away from the Moon.  This results in more water being displaced in these directions, resulting in high tide.  One gets the higher tides, called spring tides, when the gravitational force of the Sun is added to that of the Moon, which makes the bulge on the Earth’s surface a bit larger than that caused by the Moon alone.  These spring tides happen around New and Full Moon.

Jeff Mangum