Phobos
Mars's larger moon, slowly spiralling inward.
Phobos is the larger and inner moon of Mars, an irregular body with a mean radius of 11 km. It orbits only 6,000 km above the Martian surface, closer than any other known moon to its planet, completing an orbit in 7 hours 39 minutes, so it rises in the west and sets in the east.
It is one of the darkest bodies in the Solar System, has the large crater Stickney, and is drawing closer to Mars by about 2 cm a year. Asaph Hall discovered it in 1877.
Quick Facts
- Discoverer
- Asaph Hall
- Discovered
- 18 August 1877
- Adjectives
- Phobian ˈ
- f
- oʊ
- b
- i
- ə
- n
- Average speed
- 2.138 km/s
- Inclination
- 1.093° (to Mars's equator)
- 0.046° (to local Laplace plane)
- 26.04° (to the ecliptic)
- Satellite of
- Mars
- Escape velocity
- 11.39 m/s (41 km/h)
- Rotation
- Synchronous
More in Celestial Bodies & Worlds
Elsewhere in Cosmos Codex
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