SpaceAbout Mars
Mars is often called the Red Planet, because iron minerals in its soil oxidise, or rust, and make the surface look red. It is home to Olympus Mons, the largest volcano in the solar system. Mars has two small moons, Phobos and Deimos, which may be captured asteroids.
Source: NASA, read on 12 November 2026.
Mars compared with Earth
Size. Mars is 6,792 km across. That is 53% of the width of Earth (12,756 km). You would need about 1.9 of it in a row to match the width of Earth. Its mass is 0.108 times Earth's.
Gravity and your weight. Gravity at the surface is 3.7 m/s², against 9.8 on Earth. So things weigh 38% of what they do on Earth. Someone who weighs 50 kg on Earth would feel like 18.9 kg there. Try your own weight in the weight calculator.
Day. Mars turns once on its axis in 24.6 hours. From one noon to the next, its day lasts 24.7 hours.
Year. One trip round the Sun takes 687 Earth days, which is 1.88 Earth years. A ten-year-old on Earth would be 5.3 years old there, counting in that world's years. See the age calculator.
Distance. Mars is on average 228 million km from the Sun, between 206.7 million km at its closest and 249.3 million km at its farthest. Sunlight takes 12.7 minutes to arrive. That is 1.52 times Earth's distance.
Tilt and temperature. Its axis is tilted by 25.2°. A tilt like this gives it seasons, as on Earth (23.4°). The mean temperature in the fact sheet is −65 °C.
Moons, rings and magnetism. The fact sheet counts 2 moons for Mars. Rings: no. A global magnetic field: no.
All the figures
| Diameter | 6,792 km |
|---|---|
| Mass | 0.642 × 10²⁴ kg |
| Density | 3,934 kg/m³ |
| Gravity | 3.7 m/s² |
| Escape velocity | 5 km/s |
| Rotation period | 24.6 hours |
| Length of day | 24.7 hours |
| Distance from the Sun | 228 million km |
| Closest | 206.7 million km |
| Farthest | 249.3 million km |
| Orbital period | 687 days |
| Orbital velocity | 24.1 km/s |
| Orbital inclination | 1.8° |
| Orbital eccentricity | 0.094 |
| Tilt of axis | 25.2° |
| Mean temperature | −65 °C |
| Surface pressure | 0.01 bar |
| Moons | 2 |
| Rings | No |
| Global magnetic field | No |
Figures: NASA NSSDCA Planetary Fact Sheet, last updated by NASA on 18 March 2025, read on 12 November 2026. NASA rounds these values. Counts of moons change as new ones are confirmed.
Common questions
How big is Mars compared with Earth?
Mars is 6,792 km across, 0.53 times the diameter of Earth.
How long is a day on Mars?
From noon to noon, a day on Mars lasts 24.7 hours.
How many moons does Mars have?
The NASA fact sheet read on 12 November 2026 gives 2.