I am changing the subject line all the time to keep all the subterranian stuff off Regners thread. (pun intended) Neville said.. "What varies from night to night is which section of your particular celestial hemisphere you can see, since the Sun is constantly changing its rising/setting times, and you can't see the stars when the Sun is in the sky." Yes I can see this is the reason from the geocentric view. In effect the sun is not circling the earth as fast as the celestial sphere of stars, and as a consequence over the period of a year we end up getting a view of the full 360 degrees of the sphere. sidereal day 23 hours, 56 minutes. Sun takes 24 hours. slipping behind 4 minutes every day.. It is neat that the heliocentric system seems the more natural as regards the universal laws of motion. But it is supernaturalism versus naturalism. From all the recent posts, I still don't have a clue what everyone is talking about, and I'd hazard, nor does anybody else myself included. I'll eventually come up with an all encompassing valid question.. Philip.