The Moon & Tides

Tides in Motion

Tides Tides- the cyclic rise and fall of ocean water on Earth caused by the gravitational attraction of the moon and to a lesser degree, the sun. High tide- a bulge of water on Earth directly under the moon’s position, and on the opposite side of the planet Low tide- at right angles to the position of high tide the pull of the moon is least so the levels of ocean water are low.

Tides Why does the sun have less of an effect on the tides than the moon does? Because the sun is farther away. Gravity is dependent on mass & distance, so although the sun is much more massive, it is also so far away that the moon has a greater impact.

Timing of Tides The approximate time between two high and two low tides is 12 hours 25 minutes. A complete cycle of two high and two low tides would be about 24 hours and 50 minutes.

Tides Mt. St. Michel on the north coast of France at low tide Mt. St. Michel at high tide

Types of Tides Spring Tides During the new and full moon phases, when the Earth, moon, and sun are in a straight line, the high tides are higher than normal and the low tides are lower than normal (greater difference)

Spring Tides

Types of Tides Neap Tides During the quarter phases, when the Earth, moon & sun are at right angles, the high tides are lower than normal and the low tides are higher than normal (less difference between tides)

Neap Tides

Tides in Motion