Earth, Earth Sciences, The Moon

What Causes Tides On Earth?

What Causes Tides On Earth?

Scientists find tides to be of immense interest and sometimes cause for concern. Why is that and why care about tides anyway? Scientists measure ocean tides to navigate ships safely and engineers need tide data to construct bridges and docks. Also, fishermen, boaters, and surfers rely fully on tidal data for their well-being and a successful day. Oceanographers study tidal fluctuations to better understand the circulation of the ocean and its relationship to world climate changes.

What Causes The Tides?

Generally speaking, gravity causes tides on Earth. Tidal generating forces are based on the gravitational attractive force between the Earth, moon, and sun. The moon is the most influential in dictating the tides. Simply put, the earth’s movement as the moon circles it causes a force on the oceans, therefore, creating tides.

The Sun vs. The Moon’s Tide-Generating Force

It is interesting to note that many would guess that the sun being 27 million times more massive [in size] than our moon should have more force to generate tides when compared to the moon. The fact is that the sun is 390 times further from the Earth than is the moon. Therefore, the sun’s tide-generating force is significantly reduced due to its distance from Earth.

Water Bulges = High Tides

Since the gravitational force favours the moon, the ocean water is always bulging in the direction of the moon. This movement is called the tidal force. The tidal force is what causes the water to bulge towards the moon and the bulge is what we refer to as high tide.

The Near Side And Far Side Of Earth Explained

Earth is always in motion and the changing angles create varying tides. The near side refers to the gravitational attraction between the Earth and the moon on the side of Earth that is the closest to the moon. This force creates a bulge of water on the near side. Alternatively, the far side is when the gravitational force is on the side of Earth that is further away from the moon. These gravitational forces will create bulges in the ocean on both sides of the planet as the near side pulls the water towards the moon and the far side will pull the water away from Earth. Interestingly enough due to this gravitational force tug of war, both coastal areas on the near and far side will experience high tide twice a day.

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Lisa Zukerman
Lisa is a space and astronomy enthusiast who believes the epic Star Wars series should be a mandatory part of the high school curriculum. She likes to soak up random and valuable knowledge about the beautiful and sometimes strange universe we live in.