The rise and drop of sea levels caused by the gravitational force of the Moon.



tide, ebb tide, flood tide, gravity, Moon, gravitation, Sun, sea, high tide, low tide, tsunami, neap tide, nature, geography

Related items



The gravity of the Moon, and to a lesser extent that of the Sun, are responsible for changes in the sea level on the Earth. The Moon attracts the water in the oceans and the seas, so water rises on the side of the Earth facing the Moon and forms a bulge of water.

Orbiting around a common center of mass, the Earth and the Moon form a "double planet". Since the Earth is much larger, the common center of mass lies in the interior of the Earth. On the other side of the Earth, opposite the common center of mass, the centrifugal force also pulls the oceans and the seas towards it, creating another bulge of water there.
Thus there are simultaneously two bulges of water on the Earth, which travel around the oceans and seas due to the rotation of the Moon around the Earth. In some areas, tides can change every six hours.

The highest level of water is called high tide, while the lowest level is low tide. The fall in water level from high tide to low tide is called ebb tide; the rise in water level, from low tide to high tide is called flood tide. The tides are also affected by the gravitational pull of the Sun, but to a lower extent.

At New Moon, when the Earth, Moon and Sun are aligned, the Sun reinforces the pull of the Moon and sea levels are higher than usual. This is called spring tide. When the Earth, Moon and Sun form a right angle, the Sun weakens the pull of the Moon, so high tide is lower than usual. This is called neap tide.

Related items

Tidal power station

Tidal power stations utilize the daily fluctuation of the water level for producing electricity.

Formation of the Earth and Moon

This animation demonstrates how the Earth and the Moon were formed.

Apollo 15 mission (Lunar Rover)

The animation shows the two-seater Lunar Rover used in the Apollo 15 mission

El Niño

A periodic climate pattern that occurs across the tropical Pacific Ocean every five years.

How do seas shape the Earth's surface?

Seawater, as an external force, plays an important role in shaping coastlines.

Layers of the ocean

Physical properties, as well as the flora and fauna of the ocean change with depth.

Moon landing: July 20, 1969

Neil Armstrong, one of the crew members of Apollo 11 was the first man to set foot on the Moon.

Ocean currents

The Great ocean conveyor is a planet-wide system of ocean currents, which has a great influence on the Earth´s climate.

Phases of the Moon

During its orbit around the Earth, the visibility of the Moon's illuminated part constantly changes.

Solar eclipse

When the Sun, Earth, and the Moon are arranged in a straight line, the Moon can partially or completely obscure the Sun.

The Moon

The Moon is the Earth's only natural satellite

The Zuiderzee Works and the Delta Works (Netherlands)

Remarkable civil engineering works to continue the Netherland's centuries-long fight against the sea.

Types of waves

Waves play an extremely important role in many areas of our lives.

What is the time?

A game to practice the use of analog and digital clocks.

Lunar eclipse

Lunar eclipses occur when the Moon passes through the shadow cone of Earth


The animation shows the way forces act on wheeled vehicles and vehicles with runners.


Tsunami waves are very high waves of immense destructive power.

Added to your cart.