If Moon is departing, what will happen to Earth?

[Jet2]

Recently watched a TV program talking about this fact:
The distance between Earth and Moon is increasing by 1.5 inches per year.
That means Moon is drifting away from us. Though it may take many billions of year for it to totally disappear.

Of course we may not be able to witness the final outcome. I am just wondering what it will happen eventually?

Will human being be able to fix it by find ways to keep the Moon always be with us?

[Jay-qu]

I think the most noticeable difference (after a very long time) would be that the tides will start to become smaller.

And I must stress a very long time. You see, the moons orbit is not circular currently it orbits between 360,000 and 405,000km thats a range of over 45,000km or 4.5billion centimeters! So the 3.75cm avg extension per year isnt going to be noticed for a while!

Doing some quick calculations, to make a 1% change in the average Earth-Moon distance (less than the normal fluctuations in distance) it would take 100 thousand years!

[Jet2]

I think the departing speed will get faster and faster (though it may take very looooooong time) when the Earth-Moon distance is getting bigger, right?

[Jay-qu]

true, but hardly noticeable over a 1% distance, when it gets a lot further the speed it departs would have to be taken into account.

[Qfwfq]

Originally Posted by Jet2

I think the departing speed will get faster and faster (though it may take very looooooong time) when the Earth-Moon distance is getting bigger, right?

No, for two reasons: the fact that greater distance could only make the effect even tinier and, is on top of this, it is due to tides which get smaller as distance increases.

What is less tiny is the fact that tides are slowing Earth's rotation. This is the same reason for which the moon has come to be showing us the same face all the time; eventually our day will also last the same as a lunar orbit, with both orbs showing each other the same face. This would be an equilibrium, save for the gradient of the sun's field or other perturbations.

[C1ay]

Originally Posted by Jet2

Recently watched a TV program talking about this fact:
The distance between Earth and Moon is increasing by 1.5 inches per year.
That means Moon is drifting away from us. Though it may take many billions of year for it to totally disappear.

The Sun will gobble up the Earth in another 5 billion years anyhow so I wouldn't worry much about the moon drifting off...

[Zythryn]

Another effect I heard about is that the presense of the moon acts to 'stabilize' the procession of the axis of the earth. Leading to more stable seasons. As the moon gets further away, this effect won't be as strong.
Again, this is on a very long geological timescale (100s of millions of years). It should be fascinating, but I don't think anyone is going to be patient enough to document the whole process

[CraigD]

Originally Posted by C1ay

The Sun will gobble up the Earth in another 5 billion years anyhow so I wouldn't worry much about the moon drifting off...

This is no longer an accurate description of the consensus of future-of-the-solar-system science.

Astronomical observation and modeling in the last decade or so has resulted in a stellar evolution model in which stars like the Sun lose much more mass in the process of becoming red giants than previously predicted. As a result, the radii of the orbits of all of the planets will increase, so although the Sun will still swell to nearly 1 Earth orbit radius about 5.5 billion years from now, the Earth will no longer be close enough to be engulfed.

I’ve encountered recent (1997+) papers and articles giving various predictions, some of which predict that Venus will be engulfed, others that it will not. All, however, agree that Earth will not be.

Even though it will not be engulfed and disintegrated, the increased amount of solar radiation received by the Earth is expected to utterly devastate it, evaporating the oceans and eventually dissipating the atmosphere, and possibly even melting its surface. So, as C1ay opines, the ultimate fate of the Moon seems unimportant in comparison.

Source: Red giant - Wikipedia, the free encyclopedia (contains references)