The astronomers then conducted an analysis called a Bouger correction in order to subtract the gravitational effect of topological features, such as valleys and mountains, from the total gravity field. What is then left is the gravity field hidden beneath the lunar surface, existing within its crust.
Earth's mysterious large Moon is our nearest neighbor in space, dominating our clear night sky with its beguiling and bewitching cold golden glow. Earth's Moon is the only body beyond our planet that we have visited, leaving our footprints embedded in its alien dust. Despite its close proximity to our planet, our mysterious Moon has still managed to keep some ancient secrets from us very well. However, in October 2014, using data derived from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission, a team of planetary scientists announced that they may have solved a lunar mystery almost as old as our Moon itself.
Enceladus: Enceladus has shown geysers of water that were confirmed by the Cassini spacecraft in 2005. Gravimetric data obtained from 2010 to 2011 confirmed the existence of a subsurface ocean. Even though originally it was thought to be localized, most likely in a region of the icy moon's southern hemisphere, evidence collected in 2015 indicates the subsurface ocean is actually global. Furthermore, in additon to water, these geysers from vents located near the south pole of Enceladus contain tiny quantities of salt, nitrogen, carbon dioxide, and volatile hydrocarbons. Tidal flux from Saturn is apparently responsible for the melting of the ocean water, as well as the geysers.