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The Moon, Where Is It Going?
The Moon orbits the earth on a 27-day cycle and doesn't float away as it is held in our gravity (in away) but it doesn't crash into us either because of two reasons. The first reason it doesn't crash into the Earth is because of the Sun and the second is the Earth.
The Sun's effect on the Moon
The Sun is very large in mass so it has a larger gravitational pull than Earth does. The Sun's gravity is why all the planets in our solar system orbit the Sun. This pulling effect the Sun has affects the Moon. While the Earth is pulling the Moon toward us the Sun is pulling the Moon away.
The Earth's pushing effect
The Moon has its own gravitational force as the Moon is smaller than the Earth It has less gravitational force than the Earth. But the Moon's gravity still has an effect on Earth this effect Is the tides. A high tide is where the water is highest and the gravitational forces are the highest, low tide is where the water goes out and the gravitational forces are lower. You have two high tides and two low tides a day. This is because the Moon's gravitational forces pull at the Earth stretching it on the side facing the Moon and the side not facing the Moon. The side facing the Moon and the side not facing the Moon is where the gravitation force from the Moon is stronger pulling the water to it so you get high tide. The gravitational force from the Moon is weakest at halfway between the side facing the Moon and the side facing away from the Moon this happens in two places. Since the gravitation force is lower in these two places the water is pulled away from them so you get low tide. Because the Earth rotates you get two high tides and two low tides in a day. Because of this tidal force system energy dissipates between the Moon and the Earth causing the Earth to spin slightly slower. This causes the Moon's orbit to be larger, therefore, it is being pushed away.(1).
If the forces pulling the Moon towards the Earth and the forces push/pulling the Moon away from the Earth were the same then it would be fine but they're not. The forces push/pulling the Moon away are slightly stronger than the force pulling the Moon towards the Earth. So the Moon is slowly getting further away from the Earth. But I wouldn't worry because the Moon is moving away so slowly about 3.8 cm a year. The time it gets far enough for it to have an effect on Earth. The Sun would have turned into a red giant and made the Earth unlivable.
The Moon used to be a lot closer to the Earth, around 4.5 billion years ago when the Moon was first formed. It sat a distance of 14,000 miles (the length of America 5 times) compared to today where it sits at 25,0000 miles away (the length of America 89 times). The difference being 236,000 miles (the length of America 84 times).(2)
1.How the Moon affects tides. Retrieved from: https://www.timeanddate.com/astronomy/moon/tides.html
2. Why the Moon is moving away. Retrieved from: http://www.bbc.co.uk/news/science-environment-12311119
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