Featured planetary moon
Proteus
A large irregular moon that never became fully round.
Proteus is among the largest irregularly shaped bodies known. Its gravity was not sufficient to erase its angular outline, while large impacts left a heavily modified surface.
- Orbit representation
- Representative mean elements
- Surface
- procedural reconstruction
Reference measurements
The numbers that shape this world
- Mean radius
- 208 km
- Mean orbital distance
- 117,600 kmSemi-major axis around the parent body.
- Orbital period
- 1.122 days
- Eccentricity
- 0
- Inclination
- 0°Local Laplace plane from the JPL pole
- Rotation
- Tidally locked
World portrait
A body near the threshold of roundness
Proteus makes shape itself a scientific metric. Its irregular geometry is preserved in the visual profile rather than hidden behind a perfect sphere.
System geometry
Proteus in motion around Neptune
Proteus travels at a mean orbital distance of 117,600 km and completes a circuit in 1.122 days. Its eccentricity of 0 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.
Reference-guided visual reconstruction based on cited mission records; no source raster is reproduced.
Provenance