The existence of such powerful roaring winds kicking up violent and powerful dust storms suggests that the underlying sand can be set in motion, too, and that the giant dunes covering Titan's equatorial regions are still active and continually changing.
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.
Galilean Moons Of Jupiter. One dark, clear January night in 1610, Galileo Galilei climbed to the roof of his house in Padua. He looked up at the sky that was speckled with the flickering fires of a multitude of starry objects, and then aimed his small, primitive "spyglass"--which was really one of the first telescopes--up at that star-blasted sky above his home. Over the course of several such starlit, clear winter nights, Galileo discovered the four large Galilean moons that circle around the largest planet in our Sun's family, the enormous, gaseous world, Jupiter. This intriguing quartet of moons--Io, Europa, Ganymede, and Callisto--were named for four of the numerous mythic lovers of the King of the Roman gods.