NASA Spaceflight Now

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. This cycle has been appropriately named the 'dark moon'. The cycle from one dark moon to the next is called a lunation and an average lunation calculates at about 29 days, 12 hours, 44 minutes and 3 seconds (roughly) To be fair, it does deviate in relation to the moons erratic orbit patterns and is affected by the gravity conflict between the sun and the moon. Earlier theories suggested that the craggy outline of a region of the lunar surface, named Oceanus Procellarum--or the Ocean of Storms--had resulted from a large asteroid impact. If this theory had been correct, the basin it had dug out would represent the largest asteroid impact basin scarring the lunar surface. However, mission scientists, scrutinizing GRAIL data, now believe that they have discovered new evidence that the craggy outline of this rectangular region--approximately 1,600 miles across--was actually caused by the formation of ancient rift valleys.