Moon & Sun Effects on Tides

Gravity

• The gravity of the moon pulls things on Earth toward it. The gravity of Earth keeps most things on the planet in place, but it cannot entirely control water. (See Reference 1)

High Tide

• The side of the Earth that is closest to the moon will be at high tide, because the water is being pulled toward the moon, bulging slightly off the Earth's surface. Another high tide is made on the opposite side of the Earth, caused by the force of the Earth's rotation. (See Reference 2)

Low Tide

• The sides of the Earth in between these two high tides will be at low tide since water is being pulled away from them, toward the areas at high tide. (See Reference 2)

Ebb and Flow

• The Earth's rotation means that each part of the Earth will pass closest to the moon once per day and opposite of the moon once per day, causing the two high tides and the two low tides in-between. (See Reference 2)

The Sun

• The sun's gravity also pulls on Earth's water, but it has a weaker effect. When aligned with the moon, the sun will strengthen the moon's pull, creating more extreme high and low tides called spring tides. When at a 90-degree angle from the moon, the sun will pull the water slightly away from the moon, making less apparent tides called neap tides. (See Reference 2)