Dear Neville, As you claim that the geostationary viewpoint can give rise to differect predictions from the heliocentric model I am curious: - Can you get yet different predictions from the heliocentric analysis if you assume that the moon is the (stationary) centre of the universe? - Can you get yet different predictions from the heliocentric analysis if you assume that the gravitational centre of the Milky Way is the (stationary) centre of the universe? - Can you get yet different predections from the heliocentric analysis if you assume that another galaxy is the (stationary) centre of the universe? If your answer is "no" for all of the above then you should clarify exactly how, mathematically, the earth holds this special status whereby it gives different results for the analysis when every other frame of reference does not. If your answer is "yes" for any of the above then your position is that two people residing on sufficiently separated stars would both come to different conclusions about the RELATIVE motions of the bodies in the solar system (after having taken in to account the angle from which they view it, the time it takes light to reach them (however fast and varying that may be) and assuming the universe is Newtonain). Regards, Mike.