How does the moon cause two tides everyday?
The side near to the moon is drawn towards the moon by the gravitational effect of the moon and that forms one of the two high tides of the day. The side opposite to the moon is where the second high tide of each day is formed. If you think of the earth and moon rotating around one another, you can imagine an outward force: centrifugal force – like spinning a rock on a rope – that acts on the water opposite to the moon. Centrifugal force is called a ‘pseudo force’ since it is really just inertia, but to us on the Earth, this tide appears to be sort of ‘flung outwards’ by this rotation of the Earth-Moon system.
