The tidal force exerted by one body on another is a direct consequence of gravitation.

Actually, the tidal force is the difference between the field intensity of gravity created by a body at the centre of another, and the field intensity it creates on the surface of this other body.

The Earth suffers detectable tidal forces produced by the sun and moon. The combination of both forces, together with the rotation of the Earth and the movement of the Earth and moon, create the variations in the tide that sailors know so well.

Click on Next to observe and understand these peculiar phenomena.