(The second value represents the quantity as a fraction of the terrestrial value.)
Mass 4.869e24 kg 0.815 GM 0.3249e6 km3/s2 0.815 Equatorial radius 6051.8 km 0.949 Flattening 0.0 0.0 Mean density 5204 kg/m3 0.943 Moment of inertia coefficient 0.33 0.998 J2 27e-6 0.004 Surface gravity (eq.) 8.87 m/s2 0.907 Escape velocity 10.36 km/s 0.926 Topographic range 15 km 0.750
Semimajor axis 108.2e6 km 0.723 Sidereal period 224.701 d 0.615 Tropical period 224.695 d 0.615 Eccentricity 0.0068 0.407 Inclination 3.4 deg Synodic period 583.92 d Mean orbital velocity 35.02 km/s 1.176
Bond albedo 0.72 1.87 Visual geometric albedo 0.65 1.77 Visual magnitude V(1,0) -4.40 Solar irradiance 2660 W/m2 1.928 Black-body temperature 238.9 K 0.966
Epoch 1994.0 North pole (RA and Dec) 272.76 deg / 67.16 deg Obliquity 177.36 deg Argument of prime meridian 168.12 deg at epoch Sidereal rotation rate -1.4813675 deg/d Sidereal rotation period 243.02 d
Surface pressure 92 bars Surface Density ~65. kg/m3 Scale height 15.9 km Average temperature 737 K Diurnal temperature range ~0 Wind speeds 0.3 to 1.0 m/s (surface) Mean molecular weight 43.45 g/mol Composition (near surface, by volume): Carbon Dioxide (CO2) 96.5% Nitrogen (N2) 3.5% Sulfur Dioxide (SO2) 150 ppm Argon (Ar) 70 ppm Water (H2O) 20 ppm Carbon Monoxide (CO) 17 ppm Helium (He) 12 ppm Neon (Ne) 7 ppm
Epoch JD 2449360.5 Mean distance 0.7233 AU Eccentricity 0.0068 Inclination 3.39 deg Longitude of ascending node 76.69 deg Longitude of perihelion 131.44 deg Mean longitude at epoch 282.13 deg