Cosmic Scale
Mars
Planet · 228 million km from the Sun
How big is Mars?
Mars is about 6,779 km across.
Mars is a cold desert with seasons, polar caps and the tallest volcano in the Solar System. Rivers ran on its surface billions of years ago, and finding out whether anything lived in them is the reason so many spacecraft go there.
At a glance
| Diameter | 6,779 km |
|---|---|
| Mass | 6.42 × 10²³ kg |
| Diameter compared with Earth | 0.532 × Earth |
| Year | 687 days |
| Day | 24 hours 37 minutes |
| Temperature | −140 to 20 °C |
| Moons | Phobos and Deimos |
Good to know
- Olympus Mons rises 22 km, nearly three times the height of Everest, and is as wide as France.
- Valles Marineris runs 4,000 km along the equator — it would stretch across the United States.
- Its rusty colour is iron oxide dust, the same chemistry as rust on Earth.