Solving A Lunar Mystery Almost As Old As The Moon Itself! The rectangular pattern, with its straight sides and angular corners, weakens the theory that Procellarum is an old impact basin. This is because such a mighty impact would form a circular basin. Instead, the recent study indicates that processes occurring deep beneath the lunar surface dominated the formation of this unique region.
Since its discovery centuries ago, Ganymede has been the target of a great deal of well-deserved attention from the planetary science community. Earth-bound telescopes have gazed at Ganymede's puzzling, icy surface and, in later decades, flyby space missions and spacecraft, circling around Jupiter, have scrutinized Ganymede--trying to solve its numerous mysteries. These observations ultimately unveiled a complicated, icy moon-world, whose bizarre surface showed a strange and puzzling contrast between its two main types of terrain: the dark, extremely ancient and heavily cratered surface terrain, and the much younger--but still ancient--lighter terrain showing a vast array of mysterious grooves and ridges.
Most of the moons of our Solar System are intriguing, frigid, and dimly lit ice-worlds in orbit around the quartet of outer, majestic, gaseous giant planets that circle our Star, the Sun, from a great distance. In our quest for the Holy Grail of discovering life beyond our Earth, some of these icy moons are considered to be the most likely worlds, within our own Solar System, to host life. This is because they are thought to hide oceans of life-sustaining liquid water beneath their alien shells of ice--and life as we know it requires liquid water to emerge, evolve, and flourish. In April 2017, a team of planetary scientists announced that they have discovered the presence of hydrogen gas in a plume of material erupting from Enceladus, a mid-sized moon of the ringed, gas-giant planet Saturn, indicating that microbes may exist within the global ocean swirling beneath the cracked icy shell of this distant small world. Currently, two veteran NASA missions are providing new and intriguing details about the icy, ocean-bearing moons of the gas-giant planets, Jupiter and Saturn, further heightening scientific fascination with these and other "ocean worlds" in our Solar System--and beyond.