Radius 3390 km (0.532 earth radius)
Mars is about half the radius of the earth, this means it has about 1/4 the surface area and 1/8 the volume of the earth)
Mass 6.421 x 10^23 kg (0.10745 Earth mass)
Since Mars has 1/8 the volume of earth you'd expect it to be 1/8 the mass, but it has less mass since Mars is less dense than earth.
Density 3.933 x 10^3 kg/m^3 (earth is 5.52 x 10^3Kg/m^3)
Semimajor Axis 1.52 AU (minimum 2.05 x 10^8 km, max 2.49 x 10^8 km)
This is a 22% difference in the distance to the sun at perihelion and aphelion.
Due to the inverse square law this makes a 40% difference in solar input of energy per square meter of Mars surface between the nearest and farthest distances from the sun.
Orbital period 1.88 earth years
Rotation Period 24.6597 hr, or 24 h 37 m 22.663 s (Sidereal rotation 24.6229 h)
mean solar day, 24 h, 39 m, 35.244 s known as a sol
Axis tilt 25.19 degrees (Similar to earth's tilt of 23.5 degrees)
Surface and Weather
Surface acceleration of Gravity 3.71 m/s^2 ( 0.377 g on Earth)
Atmosphere 95.32% CO2, 2.7% N2, 1.6%Ar, 0.13% O2, 0.08% CO, 0.02% H2O
Surface pressure, 6.36 mb (millibar) at mean radius
Scale height 11.1 km height at which pressure decreases by 1/e of surface pressure.
Since carbon dioxide, the main component of the atmosphere freezes out at the pole in the winter the atmospheric pressure changes during the course of the year ranging beween 4.0 to 8.7 mb. ( a mb is 1/1000 of the atmospheric pressure on earth)
Temperature of the surface -140 °C to 20 °C, -200 °F to 80 °F
Wind speeds to 30 m/s in a dust storm (60 mph)
Solar intensity 589 W/m^2 (0.431 of solar intensity on earth)
11.2 km radius mean, mass 10.6 x 10^15 kg, orbit radius 9378 km, sidereal period 0.31891 days, synchronous.
6.1 km radius, mass 2.4 x 10^15 kg, orbit radius 23459 km, sidereal period 1.26244 days, synchronous
Return to Mars
Scientific Explorations with Paul Doherty
25 Dec 2003