Mars Fact Sheet

Mars/Earth Comparison

Bulk parameters



Mars

Earth Ratio

(Mars/Earth) Mass (1024 kg) 0.64171 5.9724 0.107 Volume (1010 km3) 16.318 108.321 0.151 Equatorial radius (km) 3396.2 6378.1 0.532 Polar radius (km) 3376.2 6356.8 0.531 Volumetric mean radius (km) 3389.5 6371.0 0.532 Core radius (km) 1700 3485 0.488 Ellipticity (Flattening) 0.00589 0.00335 1.76 Mean density (kg/m3) 3933 5514 0.713 Surface gravity (m/s2) 3.71 9.80 0.379 Surface acceleration (m/s2) 3.69 9.78 0.377 Escape velocity (km/s) 5.03 11.19 0.450 GM (x 106 km3/s2) 0.042828 0.39860 0.107 Bond albedo 0.250 0.306 0.817 Geometric albedo 0.170 0.434 0.392 V-band magnitude V(1,0) -1.60 -3.99 - Solar irradiance (W/m2) 586.2 1361.0 0.431 Black-body temperature (K) 209.8 254.0 0.826 Topographic range (km) 30 20 1.500 Moment of inertia (I/MR 2 ) 0.366 0.3308 1.106 J 2 (x 10-6) 1960.45 1082.63 1.811 Number of natural satellites 2 1 Planetary ring system No No

Orbital parameters



Mars

Earth Ratio

(Mars/Earth) Semimajor axis (106 km) 227.92 149.60 1.524 Sidereal orbit period (days) 686.980 365.256 1.881 Tropical orbit period (days) 686.973 365.242 1.881 Perihelion (106 km) 206.62 147.09 1.405 Aphelion (106 km) 249.23 152.10 1.639 Synodic period (days) 779.94 - - Mean orbital velocity (km/s) 24.07 29.78 0.808 Max. orbital velocity (km/s) 26.50 30.29 0.875 Min. orbital velocity (km/s) 21.97 29.29 0.750 Orbit inclination (deg) 1.850 0.000 - Orbit eccentricity 0.0935 0.0167 5.599 Sidereal rotation period (hrs) 24.6229 23.9345 1.029 Length of day (hrs) 24.6597 24.0000 1.027 Obliquity to orbit (deg) 25.19 23.44 1.075 Inclination of equator (deg) 25.19 23.44 1.075

Mars Observational Parameters

Discoverer: Unknown Discovery Date: Prehistoric Distance from Earth Minimum (10 6 km) 55.7 Maximum (10 6 km) 401.3 Apparent diameter from Earth Maximum (seconds of arc) 25.1 Minimum (seconds of arc) 3.5 Mean values at opposition from Earth Distance from Earth (10 6 km) 78.39 Apparent diameter (seconds of arc) 17.9 Apparent visual magnitude -2.0 Maximum apparent visual magnitude -2.94

Mars Mean Orbital Elements (J2000)

Semimajor axis (AU) 1.52366231 Orbital eccentricity 0.09341233 Orbital inclination (deg) 1.85061 Longitude of ascending node (deg) 49.57854 Longitude of perihelion (deg) 336.04084 Mean Longitude (deg) 355.45332

North Pole of Rotation

Right Ascension: 317.681 - 0.106T Declination : 52.887 - 0.061T Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0) T = Julian centuries from reference date

Martian Atmosphere

Surface pressure: 6.36 mb at mean radius (variable from 4.0 to 8.7 mb depending on season) [6.9 mb to 9 mb (Viking 1 Lander site)] Surface density: ~0.020 kg/m 3 Scale height: 11.1 km Total mass of atmosphere: ~2.5 x 10 16 kg Average temperature: ~210 K (-63 C) Diurnal temperature range: 184 K to 242 K (-89 to -31 C) (Viking 1 Lander site) Wind speeds: 2-7 m/s (summer), 5-10 m/s (fall), 17-30 m/s (dust storm) (Viking Lander sites) Mean molecular weight: 43.34 Atmospheric composition (by volume): Major : Carbon Dioxide (CO 2 ) - 95.1% ; Nitrogen (N 2 ) - 2.59% Argon (Ar) - 1.94%; Oxygen (O 2 ) - 0.16%; Carbon Monoxide (CO) - 0.06% Minor (ppm): Water (H 2 O) - 210; Nitrogen Oxide (NO) - 100; Neon (Ne) - 2.5; Hydrogen-Deuterium-Oxygen (HDO) - 0.85; Krypton (Kr) - 0.3; Xenon (Xe) - 0.08

Satellites of Mars



Phobos

Deimos Semimajor axis* (km) 9378 23459 Sidereal orbit period (days) 0.31891 1.26244 Sidereal rotation period (days) 0.31891 1.26244 Orbital inclination (deg) 1.08 1.79 Orbital eccentricity 0.0151 0.0005 Subplanetary axis radius (km) 13.0 7.8 Along-orbit axis radius (km) 11.4 6.0 Polar axis radius (km) 9.1 5.1 Mass (1015 kg) 10.6 2.4 Mean density (kg/m3) 1900 1750 Geometric albedo 0.07 0.08 Visual magnitude V(1,0) +11.8 +12.89 Apparent visual magnitude (V 0 ) 11.3 12.40

Author/Curator:

Dr. David R. Williams, dave.williams@nasa.gov

NSSDCA, Mail Code 690.1

NASA Goddard Space Flight Center

Greenbelt, MD 20771

+1-301-286-1258



NASA Official: Ed Grayzeck, edwin.j.grayzeck@nasa.gov

Last Updated: 15 June 2020, DRW