Mean distance from the Sun 108,000,000 kilometres
Eccentricity of orbit 0.007
Inclination of orbit to ecliptic 3.4 degrees
Sidereal period of revolution (year) 224.7 Earth days
Rotation period 243 Earth days (retrograde)
Mean synodic period 584 Earth days
Mean orbital velocity 35 kilometres per second
Inclination of equator to orbit 177 degrees
Mass 4.87(10^24) kilograms (0.815 mass of Earth)
Diameter (atmosphere not included) 12,102.5 kilometres (0.949 diameter of Earth)
Density 5.24 grams per cubic centimetre
Number of known satellites none
Surface gravity 860 centimetres per second squared
Atmospheric composition 0.96 carbon dioxide, 0.035 molecular nitrogen,
0.0002 water; trace quantities of carbon monoxide,
molecular oxygen, sulfur dioxide, hydrogen chloride,
and other gases
Surface atmospheric pressure 90 bars
Mean surface temperature 735 K
Mean visible cloud temperature 230 +/- 10 K
^ indicates exponentiation.