Featured planetary moon
Umbriel
A dark, ancient moon with change kept mostly out of sight.
Umbriel is the darkest of Uranus’s large moons and retains a heavily cratered surface. Its subdued reflectivity and limited signs of resurfacing give it a distinctly old appearance.
- Orbit representation
- Representative mean elements
- Surface
- derived map
Reference measurements
The numbers that shape this world
- Mean radius
- 584.7 km
- Mean orbital distance
- 265,986 kmSemi-major axis around the parent body.
- Orbital period
- 4.144 days
- Eccentricity
- 0.004
- Inclination
- 0.1°Uranus equator at J2000
- Rotation
- Tidally locked
World portrait
Age expressed through restraint
Umbriel’s page avoids inventing activity where the visible record is quiet. Its value lies in the contrast between preserved impacts and the more disrupted surfaces of neighboring moons.
System geometry
Umbriel in motion around Uranus
Umbriel travels at a mean orbital distance of 265,986 km and completes a circuit in 4.144 days. Its eccentricity of 0.004 and 0.1° inclination are read against Uranus equator at J2000. 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 partial imagery prepared as a 1K display texture. Unobserved areas are softly completed from the observed hemisphere so the globe remains natural-looking in motion; the body summary identifies those regions as reconstructed rather than directly observed. Final seam, pole and landmark review remains device-dependent.
Provenance