The largest moon in our solar system is Ganymede, a satellite of Jupiter. Ganymede has a diameter of about 5,268 kilometers (3,273 miles), making it even larger than the planet Mercury. It is unique not only for its size but also for its geological diversity, featuring a mix of water ice and rocky terrain. Ganymede is the only moon known to have a magnetic field, which is likely generated by an iron-nickel core. This fascinating moon continues to be a subject of interest in planetary science, offering insights into the natural satellites of gas giants.