 |
|
The explanation of the tides is relatively simple. The moon pulls on the different parts of the Earth differently. Imagine the oceans as a layer of water on top of the Earth's crust. The moon pulls on the closest part of the Earth, the ocean facing the Moon, harder than the rest of the earth. This causes one of the two daily tides. The other tide is caused in a similar way. The rocky part of the Earth is closer to the moon than the ocean opposite of the moon. This causes the rocky part of the Earth to be pulled away from the oceans, causing a high tide on the opposite side as well.
Another interesting fact about the tides is that they are not pointed directly at or away from the moon. The tides actually run slightly ahead of the point that would directly face the moon. This is caused by a fundamental of physics. The oceans act as a break for the earth, slowly slowing the Earth down. This priciple states that if the Earth's rotation slows down, that some other from of rotation must speed up. This causes the tides to be ahead of were they should be, and also causes the moon to recede as discussed below.
The Earth was very young when it was hit by a massive, glancing blow by a Mars sized planetesimal. This collision caused a ring a rock and other debris to form around the Earth. While a lot of this debris fell back to Earth, some of it collected to form our Moon. At that point, the moon was extremely close. The sun would be completely blocked every time the moon was new. The moon at this time would have taken up a large part of the sky. Over time, because of the mass of the moon and its added rotation speed because of tidal breaking the moon has slowly drifted away to it's current point. Because of this very slow speeding up as the moon circles the Earth, the moon is continuing to get farther and farther away. Eventually the moon will completely break away from Earth orbit and it will either circle the sun by itself or the Earth and moon will become a double planet system.
