Phobos (moon)

Phobos (IPA {{IPA|/?fo?b?s/}}, Greek Φόβος: "Fright"), is the larger and innermost of Mars' two moons, and is named after Phobos, son of Ares (Mars) from Greek Mythology. Phobos orbits closer to a major planet than any other moon in the solar system, less than 6000 km above the surface of Mars, and is also one of the smallest known moons in the solar system. Its systematic designation is Mars I. The adjectival form of the name is Phobian, and in fairly common usage.

Physical characteristics

Phobos is a dark body that appears to be composed of C-type surface materials. It is similar to the C-type (blackish carbonaceous chondrite) asteroids that exist in the outer asteroid belt. Phobos's density is too low to be pure rock, however, and it is probably composed of a mixture of rock and ice.

Related Topics:
C-type - Carbonaceous chondrite - Asteroid

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The Soviet spacecraft Phobos 2 detected a faint but steady outgassing from Phobos. Unfortunately Phobos 2 failed before it could determine the nature of the material, but it is most likely water. Recent images from Mars Global Surveyor indicates that Phobos is covered with a layer of fine dust about a metre thick, similar to the regolith on the Earth's Moon.

Related Topics:
Soviet - Phobos 2 - Mars Global Surveyor - Regolith - Earth - Moon

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Phobos is highly nonspherical, with dimensions of 27 × 21.6 × 18.8 km. It is heavily cratered, and the most prominent surface feature is the large crater named Stickney, after the maiden name of Asaph Hall's wife Chloe Angeline Stickney Hall. Like Mimas's crater Herschel on a smaller scale, the impact that created Stickney must have almost shattered Phobos. The grooves and streaks on the surface were probably also caused by the Stickney impact. The grooves are typically less than 30 m deep, 100 – 200 m wide, and up to 20 km in length.

Related Topics:
Crater - Stickney - Chloe Angeline Stickney Hall - Mimas - Herschel

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