Some astronomers think that the two gas-giants do not sport solid surfaces secreted beneath their immense and heavy gaseous atmospheres, although others suggest that the jumbo-size duo do, indeed, harbor relatively small cores of rocky-icy stuff. The two other large inhabitants of the outer limits of our Sun's family are Uranus and Neptune, which are both classified as ice-giants, because they harbor large icy cores secreted deep down beneath their heavy, dense gaseous atmospheres which, though very massive, are not nearly as heavy as the gaseous envelopes possessed by Jupiter and Saturn.
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.
The scientists also ruled out the possibility that the mysterious features actually exist on Titan's surface in the form of frozen methane rain or icy lava erupted from cryovolcanoes. Such surface features would show a different chemical signature and would be visible for much longer periods of time than the bright features observed in this study. The bright features were visible from time spans of only 11 hours to five weeks.