MERCURY.
Small world. Extreme conditions.
SCHEMATIC / NOT A SURFACE MAP
01 /
The measured world
- Mean radius
- 2,439.7 km
- Mean diameter
- 4,879.4 km
- Mass
- 3.301e+23 kg
- Gravity
- 3.7 m/s²
- Escape velocity
- 4.25 km/s
- Mean temperature
- 167 °C
- Rotation period
- 1,407.6 Earth hours
- Orbital period
- 87.969 Earth days
- Mean distance from Sun
- 0.387 AU
- Reported moons
- 0
Rounded reference values. Rotation is sidereal and differs from the solar day. Giant planets have no solid surface; temperature and gravity use atmospheric reference levels. Some moon counts are omitted because discoveries change them.
Compare with EarthA closer look
A solar day lasts about two Mercury years.
Water ice survives in permanently shadowed polar craters.
Atmosphere
An extremely thin exosphere containing oxygen, sodium, hydrogen, helium, and potassium.
Discovery
Known since antiquity.