• Question: How does the moon control the tide?

    Asked by Aimski to Jim on 9 Mar 2016.
    • Photo: Jim Barrett

      Jim Barrett answered on 9 Mar 2016:

      The moon is basically a really really big rock, so it’s very heavy, and it’s quite close to us, so we actually feel some gravity from the moon.

      When the moon is over the sea, you get a great big bulge in the sea, and as the moon orbits round the earth, this bulge in the sea follows it. That’s what tides are, the bulge of water following the moon. That’s why tides go in 4 week cycles, like the moon’s orbit.

Comments

  • Photo: Adrian

    Adrian commented on :

    Through the gravitational pool on the water of Earth. During the night, the moon is on the other side of the earth, pooling the Earth to its side, thus making low tide. During the night, the move is on our side, attracting the water on this side, making high tide.

  • Photo: Scott

    Scott commented on :

    Actually it’s a little more complicated that that. True: water on the side of the Earth directly facing the moon gets pulled toward it, making a high tide. However you also get a high tide on the opposite side of the Earth at the same time, even though it’s furthest from the Moon! Therefore you get two high tides a day (as the solid Earth turns underneath the liquid water), not just one.