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Deimos is a moon of Mars.


Deimos is the smaller of Mars' two moons. Being only 9 by 7 by 6.8 miles in size (15 by 12 by 11 kilometers), Deimos whirls around Mars every 30 hours.

Like Phobos, Deimos is a small and lumpy, heavily cratered object. Its craters are generally smaller than 1.6 miles (2.5 kilometers) in diameter, however, and it lacks the grooves and ridges seen on Phobos. Typically when a meteorite hits a surface, surface material is thrown up and out of the resulting crater. The material usually falls back to the surface surrounding the crater. However, these ejecta deposits are not seen on Deimos, perhaps because the moon's gravity is so low that the ejecta escaped to space. Material does appear to have moved down slopes. Deimos also has a thick regolith, perhaps as deep as 328 feet (100 meters), formed as meteorites pulverized the surface.

Deimos is a dark body that appears to be composed of C-type surface materials, similar to that of asteroids found in the outer asteroid belt.

Discovery[]

Deimos was discovered by Asaph Hall, III at the United States Naval Observatory in Washington, D.C. on 12 August 1877, at about 07:48 UTC (given in contemporary sources as "11 August 14:40" Washington Mean Time, using a pre-1925 astronomical convention of beginning a day at noon, so 12 hours must be added to get the actual local mean time). Hall also discovered Phobos on 18 August 1877, at about 09:14 GMT, after deliberately searching for Martian moons.

It is named after Deimos, a figure representing dread in Greek mythology. The names, at first spelled Phobus and Deimus, were suggested by Henry Madan (1838–1901), Science Master of Eton, from Book XV of the Iliad, where Ares (the Roman god Mars) summons Dread (Deimos) and Fear (Phobos).

Physical characteristics[]

Deimos, like Mars' other moon, Phobos, has spectra, albedos, and densities similar to those of a C- or D-type asteroid. Like most bodies of its size, Deimos is highly non-spherical with triaxial dimensions of 15 × 12.2 × 11 km, making it 56% of the size of Phobos. Deimos is composed of rock rich in carbonaceous material, much like C-type asteroids and carbonaceous chondrite meteorites. It is cratered, but the surface is noticeably smoother than that of Phobos, caused by the partial filling of craters with regolith. The regolith is highly porous and has a radar-estimated density of only 1.471 g/cm3.

Escape velocity from Deimos is 5.6 m/s. This velocity could theoretically be achieved by a human performing a vertical jump. The apparent magnitude of Deimos is 12.45.

Name[]

Hall named Mars' moons for the mythological sons of Ares, the Greek counterpart of the Roman god, Mars. Deimos, whose name means dread, is the brother of Phobos.

Gallery[]

Refrences[]

https://solarsystem.nasa.gov/moons/mars-moons/deimos/in-depth/

https://en.wikipedia.org/wiki/Deimos_(moon)

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