Among the ringed gas giant planet Saturn's amazing collection of 62 diverse, bizarre, and beautiful moons and moonlets, sometimes one of them just seems to stand out in the crowd. Such a moon is little Methone. Looking like a shiny white egg in Space, and composed of very lightweight fluffy stuff, Methone is less dense than any other known moon or asteroid in our Solar System. In March 2013, astronomers announced at the 44th Lunar and Planetary Science Conference held in the Woodlands, Texas, that this strange little 5-kilometer-size moon is one of a batch of Space eggs in orbit around Saturn!
Dr. Porco further believes that Enceladus's orbit could have been much more eccentric in the past. The greater the eccentricity, the greater the tidal squeezing, and the resulting structural variations produce heat. In this case, the heat would have been saved inside the icy moon, melting some of the ice to replenish the liquid water sea. Dr. Porco continued to explain that "(T)he tidal flexing occurring now is not enough to account for all the heat presently coming out of Enceladus. One way out of this dilemma is to assume that some of the heat observed today was generated and stored internally in the past... (N)ow that the orbit's eccentricity has lessened, the heat emanating from the interior is a combination of heat produced today and in the past."
Only recently have space missions begun to solve this beguiling Solar System mystery--that a small number of distant moons have been successfully hiding, from the curious eyes of astronomers, life-sustaining liquid water beneath secretive shells of ice.