Dear dlham:

wrote:
....
Thanks Dave

You are welcome. I was surprised I could find the answer that easily.

http://www.fourmilab.ch/images/peri_apo/

This article states that "the moon is at perigee relative
to the earth when earth is at apogee relative to the sun
and the moon is at apogee relative to the earth when
the earth is at perigee relative to the sun."

Can anyone tell me if there is a logical explanation
why this "coincidence" occurs?? Why the moon is
closest to the earth when the earth is farthest from the
sun and visa versa??

Conservation of angular momentum. The *system* of Earth (E) and the
Moon (M) is not isolated from the Sun (S). The SEM system angular
momentum is constant (ignoring all the other bodies in the solar
system). So you can think of M picking up (or holding) some momentum
(however briefly) from the SE system.

Three-body problems are always thorny. Hopefully you will get a better
/ clearer answer from others here.

David A. Smith