The Swift Planet
Mercury
The smallest planet and the closest to the Sun, Mercury races around its orbit faster than any other world — yet its slow spin and thin atmosphere leave it scorched by day and frozen by night.
Size compared to Earth0.38× Earth's diameter
Full bar = Jupiter, the largest planet
Vital statistics
- Diameter
- 4,879 km
- Distance from Sun
- 57.9 million km
- Orbital period
- 88 Earth days
- Day length
- 59 Earth days
- Moons
- None
- Mean temperature
- 167°C
Notable facts
A single Mercury day (sunrise to sunrise) lasts 176 Earth days — two full Mercury years.
Surface temperatures swing from 430°C in daylight to −180°C at night, the widest range of any planet.
Despite being closest to the Sun, Venus is hotter — Mercury has almost no atmosphere to trap heat.
Mercury's heavily cratered face resembles our Moon and hasn't changed much in billions of years.
Next stop
Venus