# Deimos

Deimos is the second largest moon of the planet Mars. Deimos, along with Mars's other moon, Phobos, was discovered by Asaph Hall in 1877.

Deimos's orbital period is 1.26244 Earth days. Its rotation is tidally locked with Mars, which means it keeps the same face oriented towards the surface of Mars. Its orbital inclination is 0.93 degrees from the martial equator. Its orbit is nearly circular (orbital eccentricity of 0.0002) with a semi-major axis of 23460 km, or about 3.45 planetary radii.

Deimos is a relatively small moon, with uneven dimensions of 15 km x 12 km x 10 km and a mass of 2.24 x 10<math>^1</math><math>^2</math> tons. It's surface spectra and albedo are similar to carbonaceous chondrite asteroids, and it has a mean density of about 2200 kg/m<math>^3</math>. The largest craters on the moon, Swift and Voltaire, each have a radius of approximately 3 km.