The largest moon in the Solar System is bigger than Mercury and hides an ocean beneath its icy surface

When people think about moons, they usually picture small rocky companions circling much larger planets. Ganymede does not fit that picture. It travels around Jupiter, yet it is larger than Mercury, holds signs of an immense hidden ocean, and even possesses its own magnetic field. Those are characteristics more often associated with planets than their satellites. It remains officially classified as Jupiter's biggest moon, though its size and internal complexity make it one of the most unusual worlds in the Solar System. According to Nasa, Ganymede is the largest moon known, exceeding both Mercury and Pluto in size while displaying features rarely seen beyond planets themselves.What makes Ganymede one of the most planet-like moons in the Solar System At first glance, Ganymede's title as a moon seems misleading. Its diameter measures around 5,260 kilometres, making it larger than Mercury despite containing less mass because much of its interior consists of ice rather than dense rock and metal. It circles Jupiter roughly every seven Earth days while remaining locked in place, always presenting the same face to the giant planet.That combination raises an interesting contrast. If Ganyme...