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Moon
How does the moon affect tides?
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The moon plays a significant role in the formation of tides on Earth through its gravitational pull. The gravitational force between the moon and the Earth creates a tidal bulge on the side of the Earth closest to the moon and another bulge on the opposite side, which is caused by the centrifugal force resulting from the Earth-moon system’s rotation.
The gravitational attraction of the moon pulls the water on the Earth’s surface toward it, causing a high tide on the side of the Earth facing the moon. At the same time, the centrifugal force produced by the Earth’s rotation creates a bulge on the opposite side, resulting in a second high tide. These areas with high tides are known as tidal bulges.
Conversely, between these two tidal bulges, there are areas with relatively lower water levels, which are known as low tides. These occur at approximately 90-degree angles to the high tides. As the Earth rotates on its axis, locations on its surface move through the tidal bulges, experiencing two high tides and two low tides in a tidal cycle, which typically lasts about 12 hours and 25 minutes.
It’s important to note that the sun also exerts a gravitational force on the Earth’s oceans, although it is about only half as strong as the moon’s gravitational force. When the sun, moon, and Earth align during a new moon or full moon, their combined gravitational effects result in higher high tides, known as spring tides. When the sun and moon are at right angles to each other during the first quarter or third quarter moon, their gravitational forces partially cancel each other out, leading to lower high tides, known as neap tides.
In summary, the moon’s gravitational pull causes tidal bulges on Earth’s surface, resulting in the rise and fall of ocean tides.