The Magnetized Iron Core and Saline Mantle of Ganymede
Ganymede, designated Jupiter III, stands as a titan among the satellites of the solar system. With a mean radius of 2,634.1 kilometers, it is the largest moon orbiting any planet, surpassing even the planet Mercury in physical dimensions, though not in mass. As an ocean world, Ganymede represents a complex intersection of planetary geology, exhibiting a differentiated internal structure that sets it apart from its Jovian siblings. It is a world of ice and silicate rock, locked in a complex gravitational dance within the Jovian system, and it remains the only known moon to possess an intrinsic magnetic field. The bulk composition of Ganymede consists of roughly equal parts silicate rock and water ice. This massive world is fully differentiated, featuring a multi-layered interior that includes a liquid, iron-rich core, a deep silicate mantle, and a series of concentric ice and liquid water layers. The presence of a subsurface saline ocean is not merely speculative; it is support...