Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth. Simultaneously with the "tide" towards the moon, another "tide" is created on the other side of the earth, so that the waters on the other side of the earth which are away from the moon are less affected and lag behind, creating a large water-mass, so daily (every 24 hours and 50.2 minutes) every point above sea level is exposed to tides twice