|Discovered by||Asaph Hall|
|Mean radius||23,459 km|
|Revolution period||1d 6h 17.9m|
|Is a satellite of||Mars|
|Equatorial diameter||15(×12.2×11) km|
|Mean density||1.7 g/cm3|
|Rotation period||1d 6h 17.9m|
|Atmospheric pressure||0 kPa|
Deimos ("DEE mos") is the smaller and outermost of Mars' two moonss. It is the smallest known moon in the solar system, though smaller undiscovered ones undoubtedly exist around the outer planets. It was discovered on August 10 1877 by Asaph Hall.
Deimos is composed of carbon-rich rock, much like C-type (carbonaceous chondrite) asteroids, and ice. It is heavily cratered. It is probably an asteroid that was perturbed by Jupiter into an orbit that allowed it to be captured by Mars, though this theory is still in some dispute. Like most bodies of its size, Deimos is highly nonspherical with dimensions of 15×12.2×11 km.
An image of Deimos taken by the Viking 1 orbiter.
See Also: List of features on Phobos and Deimos