Solar System Exploration: Planets: Mars: Moons: Phobos: Facts & Figures

Solar System Exploration

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Facts & Figures

Phobos: Facts & Figures

Facts & Figures

Discovered By

A. Hall

Date of Discovery

1877

Orbit Size Around Mars (semi-major axis)

Metric: 9,376 km

English: 5,826 miles

Periapsis (closest)

Metric: 9,234 km

Apoapsis (farthest)

Metric: 9,518 km

Sidereal Orbit Period (Length of Year)

0.3189 Earth days

Orbit Circumference

Metric: 58,907.79 km

Average Orbit Velocity

Metric: 7696.7 km/h

Orbit Eccentricity

0.0151

Orbit Inclination

1.075 degrees

Mean Radius

Metric: 11.1 km

By Comparison: 13.4 x 11.2 x 9.2 km, potato shape

Equatorial Circumference

Metric: 69.7 km

Volume

Metric: 5,729 km³

Mass

Metric: 10,658,529,896,187,200 kg

Scientific Notation: 1.0659 x 10¹⁶ kg

Density

Metric: 1.872 g/cm³

Surface Area

Metric: 1,548.30 km²

Surface Gravity

Metric: 0.0057 m/s²

Escape Velocity

Metric: 41 km/h

English: 25 mph

Scientific Notation: 11 m/s

Sidereal Rotation Period (Length of Day)

0.3189 Earth days

7.65 hours

By Comparison: Synchronous with orbital period

NASA Official: Kristen Erickson

Advisory: Dr. James Green, Director of Planetary Science

Outreach Manager: Alice Wessen

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