FAST FACTS: Mars Moon – Phobos

phobos

Phobos  is the larger and closer of the two small moons that orbit Mars; the other moon being Deimos.

Discovered By
A. Hall
Date of Discovery
1877
Average Distance from Mars
Metric: 9,378 km
Equatorial Radius
Metric: 13.4 x 11.2 x 9.2 km
Mass
Metric: 10,630,000,000,000,000 kg
Scientific Notation: 1.063 x 1016 kg
Rotation Period (Length of Day)
1.026 Earth days
24.62 hours
By Comparison: Synchronous with Mars
Orbit Period (Length of Year)
0.31891023 Earth days
Orbital Eccentricity
0.015
Orbital Inclination to Ecliptic
1 degree