The GRAIL mission determined the internal structure of the Moon in great detail for nine months during 2012. Armed with this the new information, GRAIL astronomers were able to redefine the sizes of the largest impact basins on the lunar surface.
Dr. Soderblom further explained to the press that the gravity signatures of the larger craters especially may shed new light into the number of impacts Earth's Moon, and other bodies in our Solar System, suffered during the asteroid-rampage that characterized the Late Heavy Bombardment.
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.