Featured planetary moon
Phobos
A dark, fast moon skimming close above Mars.
Phobos circles Mars in less than a Martian day, so it would appear to move quickly across the sky from west to east. Its irregular form and close orbit make it feel less like a distant moon and more like a captured fragment passing overhead.
- Orbit representation
- Representative mean elements
- Surface
- derived map
Reference measurements
The numbers that shape this world
- Mean radius
- 11.1 km
- Mean orbital distance
- 9,375 kmSemi-major axis around the parent body.
- Orbital period
- 7.65 hours
- Eccentricity
- 0.015
- Inclination
- 1.1°Local Laplace plane from the JPL pole
- Rotation
- Tidally locked
World portrait
A moon on an inward path
Phobos occupies a compact orbit inside synchronous altitude. The page keeps that orbital scale visible without presenting the representative visual motion as navigation-grade prediction.
System geometry
Phobos in motion around Mars
Phobos travels at a mean orbital distance of 9,375 km and completes a circuit in 7.65 hours. Its eccentricity of 0.015 and 1.1° 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