Lunar laser ranging reexamined: The non-null relativistic contribution

There are three relativistic contributions to the Earth-Moon range oscillation with a synodic month period which are dimensionally larger than the experimental accuracy of lunar-laser-ranging observations. These relativistic effects vanish identically, however, in general relativity because of special symmetry features of that theory's post-Newtonian structure: they provide, in effect, three null tests of general relativity. The leading-order non-null general-relativistic contribution to the synodic month range perturbation is found to have an amplitude of about 6 cm, of the same order as the present experimental accuracy of the observations.