Deimos (moon)

Deimos
Deimos-MRO.jpg
An enhanced-color image of Deimos (MRO, 21 February 2009).
Image: NASA/JPL-Caltech/University of Arizona
Discovery
Discovered byAsaph Hall
Discovery date12 August 1877
Designations
AdjectivesDeimosian
Orbital characteristics
Epoch 2012-Sep-21
(JD 2456191.5)
Periapsis23455.5 km
Apoapsis23470.9 km
23463.2 km[1] (6.92 Mars radii)
Eccentricity0.00033[1]
1.263 d[1]
(30.312 h)
1.3513 km/s[2]
Inclination0.93° (to Mars's equator)
1.791° (to the local Laplace plane)[1]
27.58° (to the ecliptic)
Satellite ofMars
Physical characteristics
Dimensions15 × 12.2 × 11 km[3]
Mean radius
6.2 ± 0.18 km[4]
(0.97316 mEarths)
495.1548 km2
(97.0755 µEarths)
Volume999.78 km3
(92.2979 nEarths)
Mass1.4762×1015 kg[2]
(0.247179 nEarths)
Mean density
1.471±0.166 g/cm3[4]
0.003 m/s2[2]
(306 µg)
5.556 m/s
(20 km/h)[2]
Synchronous[1]
Albedo0.068 ± 0.007[4]
Temperature≈ 233 K
12.89[5]

Deimos (systematic designation: Mars II)[6] is the smaller and outer of the two natural satellites of the planet Mars, the other being Phobos. Deimos has a mean radius of 6.2 km (3.9 mi)[1] and takes 30.3 hours[1] to orbit Mars. In Greek mythology, Deimos is the twin brother of Phobos and personified terror.

Deimos is 23,460 km (14,580 mi) from Mars, much farther than Mars's other moon, Phobos.[7]

Discovery

Deimos (Viking 2, 5 October 1977)[8]

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 an astronomical convention of beginning a day at noon, so 12 hours must be added to get the actual local mean time).[9][10][11][12] 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.[6] The names, at first spelled Phobus and Deimus, were suggested by Henry Madan (1838–1901),[6] Science Master of Eton, from Book XV of the Iliad, where Ares (the Roman god Mars) summons Dread (Deimos) and Fear (Phobos).[13]

Other Languages
Afrikaans: Deimos (maan)
العربية: ديموس
Avañe'ẽ: Deimos
azərbaycanca: Deymos
تۆرکجه: دیموس (قمر)
Bân-lâm-gú: Deimos (oē-chheⁿ)
беларуская: Дэймас
беларуская (тарашкевіца)‎: Дэймас
български: Деймос (спътник)
brezhoneg: Deimos (loarenn)
čeština: Deimos (měsíc)
corsu: Deimos
Deutsch: Deimos (Mond)
eesti: Deimos
emiliàn e rumagnòl: Deimos
Esperanto: Dejmo (luno)
français: Déimos (lune)
Gaeilge: Deimos
Gàidhlig: Deimos
Հայերեն: Դեյմոս
हिन्दी: डेमोस
hrvatski: Deimos (mjesec)
Ido: Deimos
Bahasa Indonesia: Deimos (satelit)
interlingua: Deimos (luna)
íslenska: Deimos
ქართული: დეიმოსი
коми: Деймос
Кыргызча: Деймос
Lëtzebuergesch: Deimos (Mound)
македонски: Дејмос
मराठी: डीमॉस
Mìng-dĕ̤ng-ngṳ̄: Deimos (ôi-sĭng)
Nederlands: Deimos (maan)
norsk: Deimos
norsk nynorsk: Marsmånen Deimos
oʻzbekcha/ўзбекча: Deymos
Plattdüütsch: Deimos (Maand)
português: Deimos (satélite)
rumantsch: Deimos (glina)
русский: Деймос
shqip: Deimosi
Simple English: Deimos (moon)
slovenčina: Deimos (mesiac)
slovenščina: Deimos (luna)
ślůnski: Deimos
српски / srpski: Дејмос
srpskohrvatski / српскохрватски: Deimos (mjesec)
suomi: Deimos
ไทย: ดีมอส
Türkçe: Deimos (uydu)
українська: Деймос (супутник)
Tiếng Việt: Deimos (vệ tinh)
吴语: 火卫二
粵語: 火衞二
Zeêuws: Deimos (maen)
中文: 火卫二