With the GRAIL data, the astronomers were able to map the gravity field both in and around over 1,200 craters on the lunar far side. This region--the lunar highlands--is our Moon's most heavily cratered, and therefore oldest, terrain. Heavily cratered surfaces are older than smoother surfaces that are bereft of craters. This is because smooth surfaces indicate that more recent resurfacing has occurred, erasing the older scars of impact craters.
When the American astronomer James Christy discovered Pluto's largest moon Charon back in 1978, astronomers were quick to calculate the mass of the system. Pluto's mass was hundreds of times smaller than the mass originally estimated for it when it was first discovered in 1930. With Charon's discovery, astronomers suddenly acquired a new understanding that something was fundamentally different about Pluto.
The new study also found that there was an amazing similarity between the rectangular structures on Earth's Moon, and those encircling the south polar region of Saturn's icy, mysterious moon, Enceladus. The patterns observed on both moons seem to be related to volcanic and tectonic processes operating on their respective moon-worlds.