Neville, i will try to comment without any copy from your text.. My question is this.. If you change the formulation to bring gravity away from the constant established, in order for there to be no gravitational pull at the height of the geostat satellite, then how do you account for the formulation still working in accord with the orbit of the moon. ? which we must assume is still attached to the world , and in the geocentric model rotating at a 24 hour orbit, and far greater centrifugal force than that attributed in the 28 day ascentric orbit. at least as it seems to me.. Philip.