NASA Mars Interior Structure

Full moons make for a wonderful setting for criminal activity, as we find in detective novels. It's that night when the gruesome murderer commits the ghastly crime and is seen by a non-descript, aged neighbor. The neighbor's claim to credibility in the witness box is the fact that there was a full moon on the night in question and everything was there for all to see; it was only a matter of chance that he or she was the only one to spot it! Full moon nights also offer the perfect cover for the snooping detective to hide behind the bush with his dim-witted assistant in tow. Europa: Planetary scientists generally think that a layer of liquid water swirls around beneath Europa's surface, and that heat from tidal flexing causes the subsurface ocean to remain liquid. It is estimated that the outer crust of solid ice is about 6 to 19 miles thick, including a ductile "warm ice" layer that hints that the liquid ocean underneath may be 60 miles deep. This means that Europa's oceans would amount to slightly more than two times the volume of Earth's oceans. A moon is a natural body that is in orbit around a planet, and it is kept in place by both the host planet's gravity and the gravity of the moon itself. Some planets possess orbiting moons; some do not. There are several theories explaining how Earth's Moon came to be. At this point, the favored model is termed the giant impact theory, often playfully called the Big Whack or Big Splash theory by astronomers when they are in a humorous frame of mind. These funny nicknames were derived from the central tenet of the theory, which is that a Mars-sized body, named Theia, smacked into the primordial Earth billions of years ago. The collision caused part of our planet's crust to be hurled violently into space. Some of this shattered, somersaulting debris was snared into Earth-orbit, where it formed a host of moonlets that were ultimately pulled together by gravity to evolve into our Moon.