← World catalog MOON / 07
Callisto
Jupiter
An ancient, heavily cratered moon with magnetic evidence for a conductive liquid layer beneath its surface.
BEvidence classStrong inference from multiple independent measurements
- Mean radius
- 2,410.3 km
- Surface gravity
- 1.235 m/s²
- Representative temperature
- about −139 °C mean surface
- Surface pressure
- Extremely tenuous CO₂ atmosphere
Scientific assessment
A subsurface ocean is plausible, but available energy and water–rock interaction are less constrained than at Europa or Enceladus.
- Liquid-water evidence
- Probable subsurface ocean inferred from induction
- Principal constraint
- Limited energy and uncertain ocean–rock contact
- Principal mission context
- Galileo archive; ESA JUICE flybys
Comparative evidence matrix
A transparent research-priority index, not a probability of life. It combines solvent evidence, usable energy, chemistry, environmental stability, evidence maturity, and sampling access.