This picture maps the variations in the Moon’s gravity field as measured by NASA’s Gravity Recovery and Interior Laboratory (GRAIL) during its mapping mission earlier this year. Very precise microwave measurements between two spacecraft, named Ebb and Flow, were used to map gravity with high precision and improved resolution, blocks on the surface about 20 km (12 mi). The measurements are three to five orders of magnitude better than previous data. Red shows to mass excesses, and blue corresponds to mass deficiencies. BTW, the map shows more small-scale detail on the far side of the moon compared to the nearside. The far side has many more small craters.
Image Credit: NASA