If you live close to the coast, you probably know that water hits a high and low level throughout the day.
When water is at its maximum height, then it’s high tide. But when water is at its lowest height, it’s low tide.
High tide usually lasts about 6 hours. And it’s generally the same for low tide. Also, tides hit a high and low usually twice a day.
But what causes tides? And why are there low and high tides?
The effects of the moon on ocean tides
The main reason that causes ocean tides is from the gravitational attraction between the moon and Earth.
When the moon is close to the Earth, it stretches the side of the planet that it’s facing. Similarly at the other side of the Earth, it bulges but the gravitational force is weaker.
As the Earth rotates, the bulge shifts to the side facing the moon. The side that is closest to the moon has a high tide because the moon pulls the body of water close to it.
But because oceans hold a set amount of water, water levels rise in one area and drop in another area. This is when there are high and low ocean tides.
Our enormous sun, which holds 99.9% of the total mass of the solar system, has an effect on ocean tides as well. But it’s not as strong as the moon because the sun is farther in distance.