Planet Mercury
Mercury

Mass (kg) 3.303e+23
Mass (Earth = 1) 5.5271e-02
Equatorial radius (km) 2,439.7
Equatorial radius (Earth = 1) 3.8252e-01
Mean density (gm/cm^3) 5.42
Mean distance from the Sun (km) 57,910,000
Mean distance from the Sun (Earth = 1) 0.3871
Rotational period (days) 58.6462
Orbital period (days) 87.969
Mean orbital velocity (km/sec) 47.88
Equatorial surface gravity (m/sec^2) 2.78
Equatorial escape velocity (km/sec) 4.25
Mean surface temperature 179C
Maximum surface temperature 427C
Minimum surface temperature -173C
Atmospheric composition: Helium 42%, Sodium 42%, Oxygen 15%, Other 1%