Mars Fact Sheet
Mars/Earth Comparison
Bulk parameters
Mars Earth Ratio (Mars/Earth) Mass (1024 kg) 0.64185 5.9736 0.107 Volume (1010 km3) 16.318 108.321 0.151 Equatorial radius (km) 3397 6378.1 0.533 Polar radius (km) 3375 6356.8 0.531 Volumetric mean radius (km) 3390 6371.0 0.532 Core radius (km) 1700 3485 0.488 Ellipticity (Flattening) 0.00648 0.00335 1.93 Mean density (kg/m3) 3933 5515 0.713 Surface gravity (m/s2) 3.69 9.78 0.377 Escape velocity (km/s) 5.03 11.19 0.450 GM (x 106 km3/s2) 0.04283 0.3986 0.107 Bond albedo 0.250 0.306 0.817 Visual geometric albedo 0.150 0.367 0.409 Visual magnitude V(1,0) -1.52 -3.86 - Solar irradiance (W/m2) 589.2 1367.6 0.431 Black-body temperature (K) 210.1 254.3 0.826 Topographic range (km) 30 20 1.500 Moment of inertia (I/MR2) 0.366 0.3308 1.106 J2 (x 10-6) 1960.45 1082.63 1.811
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) 24.13 29.78 0.810 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 Obliquity to orbit (deg) 25.19 23.45 1.074
Mars Observational Parameters
Discoverer: Unknown
Discovery Date: Prehistoric
Distance from Earth
Minimum (106 km) 54.5
Maximum (106 km) 401.3
Apparent diameter from Earth
Maximum (seconds of arc) 25.7
Minimum (seconds of arc) 3.5
Mean values at opposition from Earth
Distance from Earth (106 km) 78.39
Apparent diameter (seconds of arc) 17.9
Apparent visual magnitude -2.0
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
Martian Atmosphere
Surface Pressure: ~6.1 mb (variable) [6.9 mb to 9 mb (Viking 1 Lander site)]
Surface Density: ~0.020 kg/m3
Scale height: 11.1 km
Average temperature: ~210 K
Diurnal temperature range: 184 K to 242 K (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 g/mole
Atmospheric composition (by volume):
Major : Carbon Dioxide (CO2) - 95.32% ; Nitrogen (N2) - 2.7%
Argon (Ar) - 1.6%; Oxygen (O2) - 0.13%; Carbon Monoxide (CO) - 0.08%
Minor (ppm): Water (H2O) - 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 Semi-major axis* (km) 9378 23459 Sidereal orbit period (days) 0.31891 1.26244 Siderial rotation period (days) 0.31891 1.26244 Orbital inclination (deg) 1.08 1.79 Orbital eccentricity 0.0151 0.0005 Major axis radius (km) 13.4 7.5 Median axis radius (km) 11.2 6.1 Minor axis radius (km) 9.2 5.2 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 (V0) 11.3 12.40 *Mean orbital distance from the center of Mars.
