Mars Fact Sheet (original) (raw)

Mars/Earth Comparison

Bulk parameters

| | Mars | Earth | Ratio(Mars/Earth) | | | ---------------------------------- | -------- | ----------------- | ----- | | Mass (1024 kg) | 0.64169 | 5.9722 | 0.107 | | Volume (1010 km3) | 16.312 | 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) | 1830** | 3485 | 0.525 | | Ellipticity (Flattening) | 0.00589 | 0.00335 | 1.76 | | Mean density (kg/m3) | 3934 | 5513 | 0.714 | | Surface gravity (mean) (m/s2) | 3.73 | 9.82 | 0.380 | | Surface acceleration (eq) (m/s2) | 3.69 | 9.78 | 0.377 | | Surface acceleration (pole) (m/s2) | 3.73 | 9.83 | 0.379 | | 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 | 0.294 | 0.850 | | 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/MR2) | 0.366 | 0.3308 | 1.106 | | J2 (x 10-6) | 1960.45 | 1082.63 | 1.811 | | Number of natural satellites | 2 | 1 | | | Planetary ring system | No | No | |

** Recent resultsindicate the radius of the core of Mars may only be 1650 - 1675 km.

Orbital parameters

| | Mars | Earth | Ratio(Mars/Earth) | | | ------------------------------ | ------- | ----------------- | ----- | | Semimajor axis (106 km) | 227.956 | 149.598 | 1.524 | | Sidereal orbit period (days) | 686.980 | 365.256 | 1.881 | | Tropical orbit period* (days) | 686.972 | 365.242 | 1.881 | | Perihelion (106 km) | 206.650 | 147.095 | 1.405 | | Aphelion (106 km) | 249.261 | 152.100 | 1.639 | | Synodic period (days) | 779.94 | - | - | | Mean orbital velocity (km/s) | 24.08 | 29.78 | 0.809 | | 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) | 1.848 | 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 |

* Mean value - the tropical orbit period for Mars can vary from this by up to 0.004 days depending on the initial point of the orbit.

Mars Observational Parameters

Discoverer: Unknown Discovery Date: Prehistoric

Distance from Earth Minimum (106 km) 54.6 Maximum (106 km) 401.4 Apparent diameter from Earth Maximum (seconds of arc) 25.6 Minimum (seconds of arc) 3.5 Mean values at opposition from Earth Distance from Earth (106 km) 78.34
Apparent diameter (seconds of arc) 17.8 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/m3 Scale height: 11.1 km Total mass of atmosphere: ~2.5 x 1016 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 (CO2) - 95.1% ; Nitrogen (N2) - 2.59% Argon (Ar) - 1.94%; Oxygen (O2) - 0.16%; Carbon Monoxide (CO) - 0.06% 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 | | | ------------------------------- | ------- | ------- | | 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 (V0) | 11.3 | 12.40 |

*Mean orbital distance from the center of Mars.

Notes on the factsheets- definitions of parameters, units, notes on sub- and superscripts, etc.

Planetary Fact Table- metric units
Planetary Fact Table- U.S. units
Planetary Fact Table- Earth ratio

Mars Home Page
Directory to other Planetary Fact Sheets

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: Dave Williams, david.r.williams@nasa.gov

Last Updated: 3 October 2024, DRW