inertial mass but not gravitational mass, the lunar orbit would appear to be polarized toward the Sun by the same amplitude. The calculation of the amplitude is complicated, but a crude estimate may be derived by multiplying the Earth’s orbital radius of by the contribution to the Earth’s mass from the self-energy to yield 75 meters. The signature of an EP violation is very simple, depending only on the distance of the Moon from the Sun. This repeats about every 29.5 days, somewhat longer than the time the Moon takes to go around the Earth once, which is 27.3 days. (This difference arises since the Earth moves along its orbit as the Moon goes around, so the Moon has to make a little more than one orbit to get back to the same position relative to the Sun.) This makes EP particularly easy to measure, since many confounding effects such as tides or weather will not repeat at 29.5-day intervals. Unfortunately, there is one effect – radiation pressure acting on the orbit of the Moon – that does repeat each 29.5 days. Fortunately, it is small, less than 4 mm, and fairly easy to model, which allows it to be subtracted out. Finally, even if the experiments show no effect, there is a tiny theoretical loophole. The measurements show the sum of the WEP and SEP violations. If the experiments show no effect, the most natural explanation is that neither WEP or SEP are violated. But it is conceptually possible that both are violated, and by equal and opposite amounts. This would be an incredible coincidence since WEP and SEP depend on very different and arbitrary properties – the exact composition of the Earth and the Moon, and their self-energies. But this unlikely case cannot be completely ruled out until either other solar system bodies are measured to similar precision, or laboratory experiments reduce the bounds on WEP violations alone. Variations in the gravitational constant Existing ranging experiments can measure the constancy of the gravitational constant, G, to about one part in per year. The expansion rate of the universe is approximately one part in per year. So if G scaled with the size or expansion of the universe, existing experiments would already have seen this variation. This result can also be viewed as experimental verification of the theoretical result that gravitationally bound systems do not partake in the general