Ganymede's Hidden Ocean: More Water Than Earth, But Locked Beneath Ice

Beneath the frozen surface of Ganymede, Jupiter's largest moon, lies an ocean of liquid water greater in volume than all of Earth's seas combined — a discovery that reframes humanity's understanding of where life might take hold in the cosmos. The water has been inferred through magnetic and gravitational measurements, yet it remains sealed beneath roughly 150 kilometres of ice, untouched and unexamined. What haunts planetary scientists is not the ocean's existence, but the unanswered question of whether it has ever touched the world above it — for in that contact, or its absence, lies the dif