What is the smaller of Mars's two natural satellites?

What is the smaller of Mars’s two natural satellites? Deimos is the smaller moon. It is also the outer moon; Mars’s larger and innermost moon is Phobos.

Deimos is a small, irregular body with a mean radius of roughly 6.2 kilometers. It orbits Mars at an average distance of about 23,460 kilometers and completes one revolution in approximately 30.3 hours. Its surface is dark and likely rich in carbon-bearing material, giving it an asteroid-like appearance.

American astronomer Asaph Hall discovered Deimos on August 12, 1877, at the U.S. Naval Observatory. He found Phobos a few days earlier, on August 18—an apparent date reversal in some retellings comes from the order in which the discoveries were announced or confirmed.

The names come from Greek mythology: Deimos personifies dread or terror, while Phobos personifies fear or panic. They are companions of Ares, the Greek counterpart of the Roman war god Mars. Deimos is therefore not Mars’s larger moon; that distinction belongs to Phobos.