When will the moon escape?

[Chiltern Ben]

Hello everyone!!!

I'm Chiltern Ben and this is my first thread. Earlier this evening I was reading about the moon being really close and I wondered when the moon will escape from the influence of Earth's gravity, because the moon is getting 2cm further away each year. Does anyone know when the moon will escape???


Chiltern Ben

[ron1863]

Hi and welcome to WAB Chiltern Ben. I don't have the foggiest idea but some of the astronomers on WAB will put you right.

Ron

[natureguy]

Hi ben, Welcome to WAB, NASA says that to completely escape the earths gravity when not travelling at escape velocity is impossible, only that the further away you get the weaker the gravitational pull gets.e.g if you were 3.73 million miles away from earth which is 17 times further than the moon is now, earths gravity would be one millionth of the strength we experience on earth. earths gravity spreads indefinately out into space in all directions so the answer to your question is the moon will never escape earths gravity completely.
hope this answers your question

[Chiltern Ben]

Hi natueguy,

Thanks for the reply! I was thinking that as the moon moves further away and Earth's gravity gets weaker, that the escape velocity would reduce until one day the moon's velocity would be fast enough for the moon to make a bid for freedom!!!

Chiltern Ben

[Picidae]

Originally Posted by Chiltern Ben

Hi natueguy,

Thanks for the reply! I was thinking that as the moon moves further away and Earth's gravity gets weaker, that the escape velocity would reduce until one day the moon's velocity would be fast enough for the moon to make a bid for freedom!!!

Chiltern Ben

Ha! Sadly freedom may be short lived if it did, I expect it would fall into the clutches of Jupiter or even Saturn where it could get blown to pieces! so it would be a phyrric victory for our Lady Diana

[carlos_dfc]

Hi

The Moon moving away is because of Earth and Moon gradually becoming 'tidally locked' to each other.

The Moon's rotation has already become locked to the Earth - so that it rotates once per orbit - this is why we always see the same side of the Moon facing the Earth.
It hasn't completely settled yet, still wobbles a bit (called 'libration') which allows us to see just a little more than half the Moon.

Over a longer period of time, our days are VERY slowly lengthening (600,000 years ago, 1 day was a little over what we would nowadays measure as 22 hours)

Eventually - Earth and Moon are heading towards synchronisation, with one month (time it takes the Moon to orbit) equally matching one Earth day (it will be MUCH longer by then)
The Moon would always appear to be in exactly the same position in the sky, and would be MUCH further away than it is now - with Earth and Moon both showing the same face to each other.

Don't hold your breath though - this will take BILLIONS of years - and IIRC, I think it has been calculated that the Sun will swell to be a Red Giant, and swallow up the Earth, long before complete tidal locking of earth and Moon would occur.

Nothing is completely settled in the Solar system - it is a highly dynamic place.
Just that our lifetimes are far too short for us to see noticeable variations in the various synchronisations between the planets/moons etc.....

[Hedge Witch]

Originally Posted by carlos_dfc

Hi

The Moon moving away is because of Earth and Moon gradually becoming 'tidally locked' to each other.

The Moon's rotation has already become locked to the Earth - so that it rotates once per orbit - this is why we always see the same side of the Moon facing the Earth.
It hasn't completely settled yet, still wobbles a bit (called 'libration') which allows us to see just a little more than half the Moon.

Over a longer period of time, our days are VERY slowly lengthening (600,000 years ago, 1 day was a little over what we would nowadays measure as 22 hours)

Eventually - Earth and Moon are heading towards synchronisation, with one month (time it takes the Moon to orbit) equally matching one Earth day (it will be MUCH longer by then)
The Moon would always appear to be in exactly the same position in the sky, and would be MUCH further away than it is now - with Earth and Moon both showing the same face to each other.

Don't hold your breath though - this will take BILLIONS of years - and IIRC, I think it has been calculated that the Sun will swell to be a Red Giant, and swallow up the Earth, long before complete tidal locking of earth and Moon would occur.

Nothing is completely settled in the Solar system - it is a highly dynamic place.
Just that our lifetimes are far too short for us to see noticeable variations in the various synchronisations between the planets/moons etc.....

Thanks Carlos, this is fascinating. A good conversation piece at a dinner party

[Chiltern Ben]

Hi Carlos,

Thanks for the explanation! It was really interesting. I guess the Earth and Moon will grow older together.

Chiltern Ben

[Ruth Daniel]

Originally Posted by Hedge Witch

Thanks Carlos, this is fascinating. A good conversation piece at a dinner party

I agree,thanks everyone fascinating stuff indeed!

[Action_Man]

But what would happen if the Moon escaped ?.

And what would happen if it were to be hit by something like the KT impact ? ...