I hope someone will answer my amature question.  I have been learning about apogee and
perigee of the moon for the first time.  I'm perplexed by the variations in the distance
of the moon from the earth from one to the next.  What causes this?

I'm also trying to figure out why the moon is in the sky longer on varying days.  It
seems to corrispond to full moons and to Apogee but not exactly.

Thanks,
Steve