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Why Are Ocean Tides on Earth Larger During a Full Moon?

-- | January 25, 2016

Question: If I am correct in assuming that the moon’s apparent waxing and waning are merely the effects of the amount of shadow it is in, and it is always the same size, why are the effects of a full moon supposedly greater. i.e. larger tides. — Rod

Answer: Both the Moon and the Sun pull on the Earth and its oceans, affecting the amount of water in any given part of the ocean, creating what we call tides. The Moon has the biggest effect on our tides. When the phase of the Moon is either full or new, the Sun, Earth, and Moon lie approximately along a line. When the Earth, Sun, and Moon are aligned in this way the affect of the Sun’s gravity on the Earth’s oceans adds to the affect of the Moon on our tides, making them more extreme. The National Oceanic and Atmospheric Administration (NOAA) has a nice description of the influence of the Moon and Sun on tides that you might want to check out for further information.

Jeff Mangum

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