Featured planetary moon
Io
A world remade by tides and relentless volcanism.
Io is locked in a gravitational rhythm with Jupiter and neighboring moons. Repeated tidal flexing supplies heat to an intensely active surface, making it one of the most geologically energetic places in the Solar System.
- Orbit representation
- Representative mean elements
- Surface
- derived map
Reference measurements
The numbers that shape this world
- Mean radius
- 1,821.5 km
- Mean orbital distance
- 421,800 kmSemi-major axis around the parent body.
- Orbital period
- 1.763 days
- Eccentricity
- 0.004
- Inclination
- 0°Local Laplace plane from the JPL pole
- Rotation
- Tidally locked
World portrait
Energy from orbital resonance
Io’s story is not simply proximity to Jupiter. Its orbit participates in a resonance that keeps tidal heating active, linking orbital mechanics directly to surface change.
System geometry
Io in motion around Jupiter
Io travels at a mean orbital distance of 421,800 km and completes a circuit in 1.763 days. Its eccentricity of 0.004 and 0° inclination are read against Local Laplace plane from the JPL pole. Synchronous rotation keeps the same hemisphere broadly oriented toward the parent body.
Representation notes
What Explore is showing
JPL fitted mean elements describe general orbit shape and orientation; they are not an accurate ephemeris.
Reviewed official global map prepared as a 1K display texture. Small no-data seams were cleaned without inventing large-scale landmarks; final seam, pole and lighting review remains device-dependent.
Provenance