Moon
Phobos
The larger, inner moon of Mars. It orbits so close that tidal forces will tear it apart or bring it down onto the surface within ~50 million years.
| Type | Moon |
|---|---|
| Parent body | Mars |
| Radius | 11 km · 0.00174 R⊕ |
| Mass | 1.066 × 10¹⁶ kg · 1.78 × 10⁻⁹ M⊕ |
| Mean density | 1.86 g/cm³ |
| Rotation period | Tidally locked (always shows the same face) |
| Orbital radius | 9,376 km (Mars) |
| Eccentricity | 0.015 |
| Orbital period | 7.65 hours |