Science Advances (2026). DOI: 10.1126/sciadv.aed8021"> Possible thermal evolution of Ganymede’s interior based on assumed initial temperatures. Credit: Science Advances (2026). DOI: 10.1126/sciadv.aed8021 Ganymede is not only Jupiter's largest moon, but also the largest in our solar system and one of the few that hosts a massive ice ocean. Adding to this planet-like moon's uniqueness is the fact that among the hundreds of moons in our solar system, Ganymede is the only one that generates its own magnetic field. While the prevailing view was that Ganymede generates this magnetic field through convection in an already-formed core, there are still uncertainties surrounding this idea. Now, a new model of Ganymede's inner evolution suggests different processes may be at play. The new model, described in a study published in Science Advances , indicates that Ganymede's core is actually still forming, and this formation is driving the magnetic field instead.…