page_title: Deimos (moon)
section_title: Discovery
hierarchical_section_title: Deimos (moon) / Discovery
caption_attribution_description: Viking 2 Orbiter image of the Martian satellite Deimos taken from 1400 km. Deimos appears smooth, but higher resolution images taken during closer approaches show the surface is covered with craters, but many of these have been partially buried or subdued by regolith. Deimos is about 14 km from top to bottom in this image.
context_page_description: Deimos is the smaller and outermost of the two natural satellites of Mars, the other being Phobos. Deimos has a mean radius of 6.2 km and takes 30.3 hours to orbit Mars. Deimos is 23,460 km from Mars, much further than Mars's other moon, Phobos. It is named for Deimos, who in Greek mythology is the twin brother of Phobos, and personifies terror.
context_section_description: 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).
caption: Deimos (Viking 2, 5 October 1977)[12]
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