Moon Moving Away: Why is it Increasing?

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In summary, the Earth-moon distance increases due to tidal movement and energy transfer. The energy lost by Earth's slowing rotation is transferred to the moon, pushing it into a higher orbit. This is similar to a man on a spinning potter's wheel transferring energy to a man sitting on a wheeled chair. The moon's gravity also slows down the Earth's rotation, causing the moon to spiral outwards. When the moon first formed, it was much closer to Earth and the tides were much larger. Eventually, the Earth and moon will become tidally locked, and the moon will no longer recede.
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JV
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I read somewhere that the distance earth-moon increases. How close by was the moon in the beginning? And what I do not understand is why. It seems to me that due to tidal movement, energy is lost. Which would result in the moon slowing down, and thus getting closer to earth. Why is the reverse happening?
 
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Energy is never completely lost. While some of the energy involved in the Earth-moon tidal interaction is radiated away as heat, some of the Energy the Earth loses when it slows its rotation is transferred to the Moon via that same interaction pushin the moon into a higher orbit.

Analogy: You have a spinning potter's wheel. Sitting beside it is a man stiing on a wheeled chair. He puts his hands out to slow the wheel. As the wheel slows, the friction between his hands and the wheel will start to drag him around the wheel. The wheel will transfer some of its energy to him.
 
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The Moon creates tides on Earth. There is a high tide below the Moon's position, and another one on the opposite side of the Earth. Because of these buldges, the Earth is not perfectly spherical. The buldges have gravity too. The buldge under the Moon is closer to the Moon than the buldge on the opposite side of Earth, so its gravity is stronger. The rotating Earth carries this bulde forward, so the Moon is always slightly lagging behind the buldge it creates. So the buldge pulls the Moon forward, which raises its orbit. If the Moon orbited in the opposite direction, or the Earth rotated in the opposite direction, the Moon would spiral in. Mars' moon, Phobos is spiraling in because it orbits the planet slightly faster than Mars rotates on its axis. So it is always slightly ahead of the buldge it creates.

The buldge also gives the Moon's gravity something to grab on to and so it slows the Earth just a little bit.

When the Moon first formed, it was probably much closer to Earth, ~30,000 km altitude. The tides it raised were HUGE, and the rate at which it receeded was much faster than today. Earth also spun much faster on its axis.

Eventually, the Moon will slow down the Earth enough that they will be tidally locked to each other. Then the Moon will receed no more. That is if the Sun doesn't turn into a red giant first.
 

1. Why is the Moon moving away from Earth?

The Moon is moving away from Earth at a rate of approximately 3.78 centimeters per year due to the effects of tidal forces.

2. How does the Moon moving away affect Earth?

The Moon moving away from Earth has a minimal effect on our planet. The main impact is a slightly longer day, as the Moon's gravity slows down Earth's rotation. This also causes the Moon to move farther away from Earth.

3. Will the Moon ever stop moving away from Earth?

No, the Moon will continue to move away from Earth, but the rate at which it does so will slow down over time. This is due to the conservation of angular momentum, as the Moon's distance from Earth increases, its rotational speed decreases.

4. How does the Moon's distance affect tides on Earth?

The Moon's distance from Earth does have an impact on tides, but it is not the only factor. The Moon's gravitational pull is the main cause of tides, and the distance between the Moon and Earth only plays a minor role.

5. Is there a limit to how far the Moon can move away from Earth?

Yes, there is a theoretical limit to how far the Moon can move away from Earth. This is known as the Roche limit, and it is the point at which the Moon's gravity is no longer strong enough to hold itself together and it would break apart. However, this is not expected to happen for billions of years.

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