Ganymede is the sole acknowledged moon with its possess magnetic subject, which leads to auroras akin to These on Earth. The auroras sway when Jupiter’s magnetic subject fluctuates, partial evidence for a big saltwater ocean. Large-effect speculation. In Wikipedia. By NASA/JPL-Caltech, Community Domain, Wikipedia Moons sort through several different processes, https://spencerafced.bloguerosa.com/33686745/the-ultimate-guide-to-best-moons