Mars Diameter:   6750 km, 0.53 Earth diameters
Planetary Mass:   6.42x1023 kg, 0.107 Earth masses 
Average Distance from Sun:    217 million km, 1.52 AU (astronomical units)
Length of Day:   24.6 Earth hours
Length of Year:   687 Earth days 
Number of natural satellites:   2 - Phobos and Deimos
Planetary ring system:    Yes     
Average temperature:    ~210 K (-63 C)
Atmospheric composition:  Very thin. Carbon dioxide gas (CO2) - 95.3% and Nitrogen (N2) - 2.7%

AU stands for astronomical unit.
One AU is the average distance from the center of the Earth to the center of the Sun:  149,597,870 km

Mars

Mass (1024 kg)                     0.64185
Volume (1010 km3)                 16.318
Equatorial radius (km)	       3397
Polar radius (km)                  3375
Ellipticity (Flattening)           0.00648
Mean density (kg/m3)               3933
Surface gravity (m/s2)             3.69
Escape velocity (km/s)             5.03
Number of natural satellites          2
Planetary ring system                No

Mars Orbital parameters

Semimajor axis (106 km)          227.92
Sidereal orbit period (days)     686.980
Perihelion (106 km)              206.62
Aphelion (106 km)                249.23
Synodic period (days)            779.94
Orbit inclination (deg)            1.850
Orbit eccentricity                 0.0935
Sidereal rotation period (hrs)    24.6229
Length of day (hrs)               24.6597
Obliquity to orbit (deg)          25.19

Semimajor axis (106 km)          Mean distance from the Sun (or other central body in the  
                                 case of satellites) from center to center in 10^6 kilometers
Sidereal orbit period (days)     The time it takes the body to make one revolution about
                                 the Sun relative to the fixed stars in days.
Synodic period (days)            The time interval between similar configurations in the 
                                 orbit (e.g. opposition) of the body and Earth, in days.
Perihelion (106 km)              The point in a body's orbit closest to the 
                                 Sun, in 10^6 kilometers.
Aphelion (106 km)                The point in a body's orbit furthest from  
                                 the Sun, in 10^6 kilometers.
Orbit inclination (deg)          The inclination of the orbit to the ecliptic, in degrees.  
                                 For satellites, this is with respect to the planet's 
                                 equator.  
Orbit eccentricity               A measure of the circularity of the orbit, equal to 
                                 (aphelion - perihelion distance)/(2 x semi-major axis)
                                 For a circular orbit, eccentricity = 0.
Sidereal rotation period (hrs)   The time for one rotation of the body on its axis  
                                 relative to the fixed stars, in hours.  A minus sign 
                                 indicates retrograde rotation.
Length of day (hrs)              The average time in hours for the Sun to move from the 
                                 noon position in the sky at a point on the equator back 
                                 to the same position, on Earth this defines a 24 hour day. 
Obliquity to orbit (deg)         The tilt of the body's equator relative to the body's  
                                 orbital plane, in degrees.

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
Maximum apparent visual magnitude            -2.91      

Martian Atmosphere

Surface Pressure:  ~6.1 mb (variable) [6.9 mb to 9 mb (Viking 1 Lander site)]
Surface Density: ~0.020 kg/m3
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 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
Sidereal 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.

Information supplied by the NASA Goddard Space Flight Center.

Alternative facts for Mars by the U.S. Geological Survey: Includes: Radius, orbital period, rotation period, etc.