rocky
Mars
The rusty desert world
Mars is a cold, dusty world where iron-rich minerals give the surface its characteristic red color. Ancient river valleys, dry lake beds, and polar ice deposits suggest that liquid water once flowed on its surface.
Key facts
- Diameter
- 6,779 km
- Radius
- 3,389.5 km
- Mass
- 6.417e+23 kg
- Gravity (Earth = 1)
- 0.377
- Density
- 3.9335 g/cm³
- Distance from Sun
- 227,900,000 km
- Orbital period
- 687 Earth days
- Rotation period
- 24.62 hours
- Average temperature
- -63°C
- Known moons
- 2
Values are approximate and based on cited sources.
Atmosphere
- Carbon dioxide
- Nitrogen
- Argon
Surface
Dusty red plains, canyons such as Valles Marineris, and the enormous volcano Olympus Mons.
Internal structure
A partly molten iron core, silicate mantle, and thin basaltic crust.
Moons
Phobos
Its extremely low orbit will one day cause it to break apart or crash into Mars.
Deimos
One of the smallest known moons in the solar system.
Exploration missions
- • Viking program
- • Curiosity rover
- • Perseverance rover
Sources
- NASA Science — Mars— last verified 2026-01-15