Planet Mars

Global mosaic of 102 Viking 1 Orbiter images of Mars taken on orbit 1,334, 22 February 1980. The images are projected into point perspective, representing what a viewer would see from a spacecraft at an altitude of 2,500 km. At center is Valles Marineris, over 3000 km long and up to 8 km deep. Note the channels running up (north) from the central and eastern portions of Valles Marineris to the dark area, Acidalic Planitia, at upper right. At left are the three Tharsis volcanoes and to the south is ancient, heavily impacted terrain. (Viking 1 Orbiter, MG07S078-334SP)

Global mosaic of 102 Viking 1 Orbiter images of Mars taken on orbit 1,334, 22 February 1980. The images are projected into point perspective, representing what a viewer would see from a spacecraft at an altitude of 2,500 km. At center is Valles Marineris, over 3000 km long and up to 8 km deep. Note the channels running up (north) from the central and eastern portions of Valles Marineris to the dark area, Acidalic Planitia, at upper right. At left are the three Tharsis volcanoes and to the south is ancient, heavily impacted terrain. (Viking 1 Orbiter, MG07S078-334SP)

Global view of Mars as seen by the Viking 1 orbiter in 1980, showing the Valles Marineris (center)
Designations
Pronunciation i/ˈmɑrz/
Adjective Martian
Orbital characteristics [1]
Epoch J2000
Aphelion 249,209,300 km
1.665 861 AU
Perihelion 206,669,000 km
1.381 497 AU
Semi-major axis 227,939,100 km
1.523 679 AU
Eccentricity 0.093 315
Orbital period 686.971 days
1.8808 Julian years
668.5991 sols
Synodic period 779.96 days
2.135 Julian years
Average orbital speed 24.077 km/s
Mean anomaly 19.3564°
Inclination 1.850° to ecliptic
5.65° to Sun’s equator
1.67° to invariable plane[2]
Longitude of ascending node 49.562°
Argument of perihelion 286.537°
Satellites 2
Physical characteristics
Equatorial radius 3,396.2 ± 0.1 km[a] [3]
0.533 Earths
Polar radius 3,376.2 ± 0.1 km[a] [3]
0.531 Earths
Flattening 0.005 89 ± 0.000 15
Surface area 144,798,500 km2
0.284 Earths
Volume 1.6318×1011 km3[4]
0.151 Earths
Mass 6.4185×1023 kg[4]
0.107 Earths
Mean density 3.9335 ± 0.0004[4] g/cm³
Equatorial surface gravity 3.711 m/s²[4]
0.376 g
Escape velocity 5.027 km/s
Sidereal rotation
period 1.025 957 day
24.622 9 h[4]
Equatorial rotation velocity 868.22 km/h (241.17 m/s)
Axial tilt 25.19°
North pole right ascension 21 h 10 min 44 s
317.681 43°
North pole declination 52.886 50°
Albedo 0.170 (geometric)[5]
0.25 (Bond)[6]
Surface temp.
Kelvin
Celsius
min mean max
186 K 210 K[6] 293 K[8]
−87 °C −63 °C 20 °C
Apparent magnitude +1.6 to −3.0[7]
Angular diameter 3.5–25.1″[6]
Atmosphere[6][9]
Surface pressure 0.636 (0.4–0.87) kPa
Composition
(mole fractions)
95.32% carbon dioxide
2.7% nitrogen
1.6% argon
0.13% oxygen
0.08% carbon monoxide
210 ppm water vapor
100 ppm nitric oxide
15 ppm molecular hydrogen[10]
2.5 ppm neon
850 ppb HDO
300 ppb krypton
130 ppb formaldehyde
80 ppb xenon
18 ppb hydrogen peroxide[11]
10 ppb methane[12]