Is the Gravitational Constant Changing

Although the question posed by the title is not yet conclusively resolved, the most recent determinations of the lunar tidal acceleration are in reasonable accord with each other, suggesting that ndot_tidal = (-28.8 ± 1.5)" century^-2. Recent lunar occultation solutions are now in accord with laser ranging results in indicating that ndot_total = (-23.2 ± 1.2)" century^-2. The difference between these results gives an excess of possible cosmological origin of ndot/n = (+3.2 ± 1.1) × 10^-11 yr^-1 which is also consistent with very preliminary results from planetary radar ranging. Interpreted with the scalar covariant cosmology of Canuto and Hsieh, these results indicate that Gdot/G = (-6.4 ± 2.2) × 10^-11 yr^-1. Implications for relativity and cosmology are briefly discussed.