NASA’s Cassini spacecraft has been lurking around the planet Saturn and collecting data relating to the planet’s moons and rings in an attempt to learn more about it. Scientists are receiving signals from the spacecraft as fast as it can transmit data; as far away as it is, it can take a while for the data to get to Earth. So far, we've received some pretty awesome photographs of Saturn and Dione (another of Saturn's moons) together, as well as some close-ups of Dione.
On the other hand, the mission has been entirely informative. The spacecraft has sent back detailed images of Saturn’s moons and rings, helping scientists learn more than they had even dreamed of, and there’s still more to come.
Cassini’s latest data illustrates that Saturn’s geologically active moon Enceladus has a global ocean underneath its thick icy crust. Scientists believe this to be the case because there is a “slight wobble” that the moon gives off as the moon orbits the planet that doesn’t quite make sense, unless of course, the surface of the moon isn’t attached solidly to the rest of the moon’s body.
"If the surface and core were rigidly connected, the core would provide so much dead weight the wobble would be far smaller than we observe it to be," said Matthew Tiscareno, a Cassini participating scientist at the SETI Institute, Mountain View, California. "This proves that there must be a global layer of liquid separating the surface from the core."
Scientists believe that the wobble comes from the thick ice crust floating atop of the global ocean, which is conveniently named because it covers the entire moon. The ice layer atop it floats on the ocean, and any centripetal force in any direction would cause this wobble that scientists have been observing for years and have been unable to explain.
Underneath the global ocean, scientists believe there is a rocky core at the heart of the moon. At the south pole of the moon, there are jets that seem to expel liquid and liquid vapors. As the crust with the holes in it presses down on the ocean, due to the centripetal force, it has to go somewhere – it spews through the small crevices and into the moon’s exosphere, where NASA’s Cassini spacecraft has been able to detect it.
NASA says that even if the crust were slightly frozen to the interior of the planet, the wobbling would be far less than they’ve been observing.
Scientists are baffled over exactly why only the surface of the moon is frozen and why the layer underneath the crust would not be. One theory goes as far as to say that the crust moving generates enough heat energy to keep the layer underneath the icy crust melted.