Mercury Facts: Distance, Size, Temperature & Moons
Planet #1 of 9 · 🔥 Fire-dominant (scorching surface conditions)
The smallest and fastest planet, scorched by day and frozen by night with almost no atmosphere to hold any heat.
View Mercury in the interactive 3D Solar System →How far is Mercury from Earth?
Mercury is 77.3 – 222 million km from Earth. This is a range rather than a fixed number because both Earth and Mercury are constantly moving along their own orbits around the Sun, so the distance between them is always changing. Mercury orbits at an average distance of 0.39 AU (57.9 million km) from the Sun, compared to Earth's 1 AU (149.6 million km).
Key facts about Mercury
Diameter
4,879 km
Temperature
-180 to 430 °C
Day length
59 days
Year length
88 days
Moons
0
Gravity
3.7 m/s² (0.38× Earth)
Escape velocity
4.3 km/s
Orbital eccentricity
0.206 (most eccentric of the 8 planets)
Composition
Rocky, iron core (~75% of radius)
Atmosphere
Almost none (trace O2, Na, H2)
Did you know?
✨ A day on Mercury (sunrise to sunrise) lasts about 176 Earth days — longer than its year.