Moon's orbit and tidal locking

In summary: Hi Don, in summary, the Moon is currently tidally locked to Earth and will remain that way unless an external force acts upon it. However, over time, the Earth's rotation will become tidally locked to the Moon's revolution and both bodies will always present the same sides to each other. This will also cause the Moon to stop moving away from the Earth in its orbit. Ultimately, the Moon and Earth will end up like Charon and Pluto, with both bodies locked in a synchronous orbit.
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The Moon is close enough to Earth that it is tidally locked, however it is also slowly but steadily moving into a wider orbit around Earth. Will there be a point in tile when the Moon is no longer locked and able to freely rotate and if so how far apart would that need to be?

Don
 
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Hi Don,

No that won't happen. Once locked, a body stays like that forever, unless some external force acts on it and supplies some extra angular momentum. In a two-body system like that of the Moon-Earth any such interaction is pretty unlikely(think huge asteroid impact, or rogue planet/star passing close by).

What will happen, given enough time, is that the Earth's rotation will get tidally locked to the Moon's revolution, with both bodies eventually presenting always the same sides to each other.
At that point in time, the Moon will also stop moving away in its orbit, as this process is simply the other side of the same coin. The same forces that cause Moon to move away cause Earth to slow down in its rotation. It has to be like that, else the angular momentum is not conserved.

In other words, Moon-Earth will end up like Charon-Pluto.
 
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Thank you very much for that very well explained answer.

Don
 

1. How long does it take for the Moon to orbit the Earth?

The Moon takes approximately 27.3 days to complete one orbit around the Earth.

2. Why does the Moon always show the same side to the Earth?

This is due to a phenomenon called tidal locking, where the Earth's gravitational pull on the Moon causes it to rotate at the same rate as it orbits, resulting in the same side always facing the Earth.

3. What is the significance of the Moon's orbit and tidal locking?

The Moon's orbit and tidal locking have a significant impact on Earth's tides, as well as on the length of our days and the stability of our planet's axial tilt.

4. Can the Moon's orbit and tidal locking change over time?

Yes, although the changes are very small and occur over a long period of time. The Moon's orbit is slowly getting larger, causing it to move away from the Earth, and its tidal locking is also slowly changing due to factors such as the Earth's rotation and gravitational influence from other planets.

5. How does the Moon's orbit and tidal locking affect space missions?

The Moon's orbit and tidal locking can affect the trajectory and timing of space missions to the Moon, as well as the landing and takeoff locations for lunar missions. It also presents challenges for potential future missions that involve establishing a permanent presence on the Moon.

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