The GRAIL spacecraft reveals small variations in our moon's gravity field.

An interesting look at variations in the gravitational field of our moon, from the GRAIL spacecraft.

Mercator projections of free-air gravity, topography, and Bouguer gravity. Frames in (A) highlight the area surrounding the Korolev impact basin, at center. Frames in (B) show the western limb of Oceanus Procellarum. Details of free-air and Bouguer gravity are the same as in Fig. 1. Topography is from a LOLA 1/64° grid.

Cf., Zuber et al., Science 8 February 2013: Vol. 339 no. 6120 pp. 668-671.
DOI: 10.1126/science.1231507

Free-air gravity adjusts the value of g for altitude above sea level; Bouguer gravity also corrects for the mass of the rock piled up to that altitude.

1000 mGal = 1000 milliGalileos = 1 cm/sec². So the variations are small but telling.

Enjoy.