The Lunar and Planetary Science Conference announced on 2015-03-16 that a 198 km wide crater has been found on the moon using the GRAIL spacecraft that uses gravitational field mapping. This enabled the discovery of craters below the surface. It's been named the Earhart crater. Nice gravitational photos can be found in the links.
(Score: 2) by NotSanguine on Saturday March 21 2015, @03:04AM
Also, I'd think that "massive" would be precisely the wrong word to use when describing a feature whose defining characteristic is having an unusual lack of mass compared to the areas around it.
Not everyone thinks like a scientist. In general usage, massive does not just mean 'high mass'.
mas·sive [google.com]
ˈmasiv/
adjective
adjective: massive
2. exceptionally large.
"massive crowds are expected"
No, no, you're not thinking; you're just being logical. --Niels Bohr