Ganymede (moon of Jupiter - for comparison)

Ganymede is the largest moon orbiting Jupiter and the biggest moon in our solar system. It measures about 5,268 kilometers (3,273 miles) in diameter—larger than the planet Mercury. Ganymede has a layered structure with a metallic core, a rocky mantle, and a surface covered by ice and some liquid water beneath. Its surface features both old, heavily cratered regions and younger, smoother areas with grooved ice. The moon also has a thin oxygen atmosphere and possibly a subsurface ocean that could harbor conditions suitable for life. Its unique geology and potential for liquid water make it a key object of scientific interest.