[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