Re: moon's synchronism

[Leigh Palmer <palmer@sfu.ca>]

> > I did not get rid of any angular momentum. Neither Earth nor Moon
> > were given spin at time zero (in the frame of reference of the
> > center of mass). Moon starts spinning (tries to show us the same
> > face). I assume this is at the expense of the orbital angular
> > momentum.
>
> Folks, the angular momentum is NOT conserved -- at least in the beginning
> and I don't see why it should be currently.  There is no requirement that it
> need be!  There is an external torque on the Moon!

The angular momentum of the Earth Moon System about its center of
mass is nearly conserved (the only shuck being that the Sun exerts
a small tidal torque*). Surely you didn't think I meant that the
angular momentum of the Moon was conserved. The model under
consideration is a classical Keplerian two body system with
plastic distortion added in. Ludwik has an elastic distortion and
John will attempt a dissipative distortion.

> What am I missing?????  I guess I just can't follow what you are talking
> about.  Somebody help this poor senile person out.

Leigh

* Given long enough (many times the age of the universe) the Earth
and Moon might approach a configuration with the Moon at the outer
Lagrange point. The dissipation mechanism would be gravitational
radiation! Presumably this would compete with the decay of the
Earth's orbit into the Sun by gravitational radiation and the
Poynting-Robertson effect, two phenomena we don't worry about at
all in this simulation.