• Question: how dose the moon control waves??

    Asked by cridland1 to Alan, Caspar, Diana, Murray, Sarah on 24 Mar 2011 in Categories: .
    • Photo: Alan Winfield

      Alan Winfield answered on 21 Mar 2011:

      I think the moon controls tides, not waves. The huge mass of the water in the earth’s oceans is large enough to be attracted by the moon – by gravitation. So on the side of the Earth facing the moon the oceans are pulled toward the moon causing a kind of bulge of water. This build-up of water moves as the moon orbits the earth about once a day and that causes approximately two bulges (high tide and low tide) every day. Waves are I think caused primarily by wind – not the moon – but I’m sure the two things – waves (caused by the wind) and tides (caused by the moon) sometimes combine. A high tide combined with a storm is I think called a storm surge.

    • Photo: Caspar Addyman

      Caspar Addyman answered on 21 Mar 2011:

      The moon controls the tides.. which in turn can change what waves you get but mostly i think waves are caused by the wind.

      How does the moon control the tides? I can’t remember exactly but i think that when it is directly over the ocean it attracts the water ever so slightly more so that there’s a bulge in the middle and drop at the ends which causes a low tide.
      But confusingly there is another bulge on the opposite side of the world where the water is pulled less towards the moon and gets left behind. So there are two tides a day.

    • Photo: Sarah Thomas

      Sarah Thomas answered on 24 Mar 2011:

      Think about gravity: imagine the fact that the moon pulls the water with it as the Earth rotates, a bit like a magnet pulling iron filings. That gravitational pull as the earth rotates causes the tides and the waves.

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