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Europa photographed by NASA's Juno spacecraft, 2022
Europa photographed by NASA's Juno spacecraft, 2022. Photo: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill · CC BY 2.0 · via Wikimedia Commons
Science & space · Jupiter system · discovered 1610; explored 1979–today

Europa's Hidden Ocean

Established1610 CE – 2026 CEJupiter's moon Europa

An icy moon with more liquid water beneath its shell than all of Earth's oceans may hold.

Research draft · editor review pending. Every claim below is linked to a checked source, but this dossier has not yet been reviewed by a human editor. Spot an error? Corrections are logged.

Europa, one of the four large moons of Jupiter discovered in 1610, has one of the smoothest surfaces in the Solar System. Measurements from the Galileo spacecraft showed that Europa disturbs Jupiter's magnetic field in a way best explained by a salty, electrically conducting ocean beneath the ice.

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How to read the labels

EstablishedSupported by strong, converging evidence.
ContestedEvidence exists but qualified scholars disagree.
UnresolvedThe question is open; evidence does not settle it.
LegendComes from myth, literature or tradition, not physical evidence.
SpeculativeA hypothesis with little direct evidence so far.

Hero image: Europa photographed by NASA's Juno spacecraft, 2022. Photo: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill · CC BY 2.0 · via Wikimedia Commons. Evidence labels describe the written claims, not the image. Version 1 · updated 2026-10-22.