Key facts
- Mean diameter
- 6,779 km
- Mass
- 6.42 × 10^23 kg (0.107 Earths)
- Surface gravity
- 3.7 m/s² (0.377 g)
- Escape velocity
- 5 km/s
- Mean temperature
- -65 °C
- Rotation period
- 24.6 hours
- Orbital period
- 687 days
- Mean distance from the Sun
- 228 million km
- Sunlight travel time
- 12 min 40.5 s
- Axial tilt
- 25.2°
- Confirmed moons
- 2
Atmosphere
Thin: about 95% carbon dioxide, with nitrogen and argon; under 1% of Earth's surface pressure.
Composition and structure
Rocky planet with an iron-rich core and a surface coloured by iron oxides.
Discovery and exploration
Mariner 4 returned the first close-up images (1965). Viking 1 and 2 landed in 1976. Rovers Sojourner, Spirit, Opportunity, Curiosity, Perseverance and China's Zhurong have explored the surface.