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Earth
Solar System
The only known inhabited world and the empirical benchmark for every habitability comparison.
AEvidence classDirectly observed or repeatedly measured
- Mean radius
- 6,371 km
- Surface gravity
- 9.807 m/s²
- Representative temperature
- +15 °C mean surface
- Surface pressure
- 1,013 mbar mean sea level
Scientific assessment
Persistent surface oceans, active geochemistry, atmospheric regulation, and a long-lived biosphere define the benchmark case.
- Liquid-water evidence
- Global surface ocean, directly observed
- Principal constraint
- Benchmark, not a target
- Principal mission context
- Earth-observing satellite constellations
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.