Discovery | |
---|---|
Discovered by | Asaph Hall |
Discovery date | 12 August 1877 |
Designations | |
Designation | Mars II |
Pronunciation | /ˈdaɪməs/[1] to /ˈdiːməs/[2] or as Greek Δεῖμος (approximated /ˈdeɪmɒs/)[3] |
Named after | Δεῖμος |
Adjectives | Deimian /ˈdaɪmiən/[4] |
Orbital characteristics | |
Epoch 23 September 2012 (JD 2456191.5) | |
Periapsis | 23455.5 km |
Apoapsis | 23470.9 km |
23463.2 km[5] (6.92 Mars radii) | |
Eccentricity | 0.00033[5] |
1.263 d[5] (30.312 h) | |
Average orbital speed | 1.3513 km/s[6] |
Inclination | 0.93° (to Mars's equator) 1.791° (to the local Laplace plane)[5] 27.58° (to the ecliptic) |
Satellite of | Mars |
Physical characteristics | |
Dimensions | 16.08 × 11.78 × 10.22 km (± 0.16 × 0.12 × 0.10 km)[7] |
6.27±0.07 km[7] | |
522±8 km2[7] | |
Volume | 1033±19 km3[7] |
Mass | 1.51×1015 kg[8] |
Mean density | 1.465±0.051 g/cm3[7] |
0.003 m/s2[6] (306 μ g) | |
5.556 m/s (20 km/h)[6] | |
Synchronous[5] | |
Albedo | 0.068±0.007[9] |
Temperature | ≈ 233 K |
12.89[10] | |
Deimos (/ˈdaɪməs/; systematic designation: Mars II)[11] is the smaller and outer of the two natural satellites of Mars, the other being Phobos. Deimos has a mean radius of 6.2 km (3.9 mi) and takes 30.3 hours to orbit Mars.[5] Deimos is 23,460 km (14,580 mi) from Mars, much farther than Mars's other moon, Phobos.[12] It is named after Deimos, the Ancient Greek god and personification of dread and terror.
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