Most of the circular impressions are impact craters.
Variance of the Moon's g field is vastly greater than Earth's. Enough so that long-lived lunar satellites are very difficult to plan as their orbits continuously devolve due to gravitational perturbations, and eventually intersect the Moon at perilune. Often in a matter of weeks or months.
https://www.nasa.gov/images/content/711375main_grail20121205...
Most of the circular impressions are impact craters.
Variance of the Moon's g field is vastly greater than Earth's. Enough so that long-lived lunar satellites are very difficult to plan as their orbits continuously devolve due to gravitational perturbations, and eventually intersect the Moon at perilune. Often in a matter of weeks or months.
Scott Manley here:
https://youtube.com/watch?v=EadClM4Y45A