Why is the Moon getting further from Earth ?

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In summary, Google says that the tides create a bulge on Earth which slows down the Earth's rotation and gravitational effects speed up the moon's revolving around the Earth.
  • #1
DaTario
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Hi All,

What is the reason that makes the distance between the Earth and the Moon get larger and larger?

Best wishes,
DaTario
 
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  • #2
DaTario said:
Hi All,

What is the reason that makes the distance between the Earth and the Moon get larger and larger?

Best wishes,
DaTario
Google is your friend. I just did a search on "moon getting farther from earth"
upload_2018-7-22_10-40-16.png
 

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  • #3
The reason is tides.

The tidal bulge risen on Earth by the Moon is offset from the line connecting the two centres of masses by Earth's rotation due to limited response time of Earth surface (and oceans) - cf. Love numbers.
The offset bulge is acted upon by gravity of the Moon, providing torque to Earth (causing slowing of rotation period) and to Moon (raising it in its orbit).

Googling for 'tidal acceleration' and selecting pictures will let you see some free body diagrams of the system.
 
  • #4
Hi DaTario:

The simple answer is that the lunar tides create a bulge of water which acts by friction to (1) slow the Earth's rotation, and (2) gravitationally to speed up the moon's revolving around the Earth. The details of the friction and the gravitational effects are too complicated for me to try to describe.

Hope this helps.

Regards,
Buzz
 
  • #5
There are also Earth tides, less obvious but significant if you've an LHC or radio-telescope array. Or are monitoring a volcano via GPS...
https://en.wikipedia.org/wiki/Earth_tide
IIRC, although the total is constrained, there is not yet agreement on how much Earth-tide energy is dissipated where within our world.

OT: Based on a small sample, you must wonder how much the Moon's tidal stirring influences our lively plate tectonics...
 
  • #6
I like to think of it like the offset bulge in the tides is pulling the moon like a horse pulling a cart. Pulling it would make it go faster but the energy goes into taking it higher in orbit around the Earth.
If the Moon were moving against the rotation of the Earth, I gather the Moon would be lowering in orbit, and reach the Roach Limit, and break up.
 

1. Why is the Moon moving away from Earth?

The Moon is moving away from Earth because of tidal forces. Tidal forces are caused by the gravitational pull of the Moon on the Earth's oceans, which creates a bulge in the Earth's surface. As the Earth rotates, this bulge also pulls on the Moon, causing it to slowly move away from the Earth.

2. How fast is the Moon moving away from Earth?

The Moon is moving away from Earth at a rate of approximately 1.5 inches (3.78 centimeters) per year. This may not seem like much, but over millions of years, it adds up to a significant distance.

3. Will the Moon eventually leave Earth's orbit?

No, the Moon will not leave Earth's orbit. While it is moving away from Earth, it is still bound to our planet by gravity. The Moon's orbit around Earth is a delicate balance between the pull of Earth's gravity and the Moon's forward motion. As the Moon moves further away, the balance may shift slightly, but it will still remain in orbit.

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

The Moon's distance from Earth does not have a significant impact on tides. The size and shape of the ocean basins, as well as the rotation of the Earth, are the primary factors that determine the strength of tides. However, as the Moon moves further away, the tidal forces will weaken, resulting in smaller tides over time.

5. Can we stop the Moon from moving away from Earth?

No, we cannot stop the Moon from moving away from Earth. This is a natural process that has been happening for billions of years and will continue to happen. However, the rate at which the Moon is moving away is very slow and will not have a significant impact on Earth in our lifetimes.

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