Alan. I'm not well versed in mathematics, but may I ask you a question. When we look at the moon in the night sky it is apparent that the moon does not orbit(?) the earth as fast as the earth rotates. I understand that if the moon orbited the earth at the same speed as the earth rotates the moon would appear to stand still in the sky, and that if it moved faster it would move to the east in the night sky The arc of travel for the moon is, thus, slower than the arc of travel for the rotation of the earth.. Thus, although you enlightened Neville, me, being a layman in these matters, still doesn't understand why if the moon's orbiting the earth slower than the earth rotates, how the moon's shadow shouldn't travel from east to west in a HC situation eclipse. I have found that most people who have a good grasp of a problem can put their explanations in fairly simple terms and was hoping you could/would do this for me. Thank you for any time you may take in this matter, Ronald Knarr