Familiar. Yet a world apart.
A day just a little longer than ours. A year almost twice as long. Get a sense of scale with the numbers that define the Red Planet.
Two rocky worlds
| Property | Earth | Mars |
|---|---|---|
| Mean diameter | 12,742 km | 6,779 km |
| Solar day | 24 hours | 24 h 39 m 35 s |
| Orbital period | 365.26 days | 686.98 days |
| Mean surface gravity | 9.82 m/s² | 3.73 m/s² |
| Natural moons | 1 | 2 |
| Mean distance from Sun | 149.6 million km | 228.0 million km |
Orbital periods are in Earth days. Diameter uses volumetric mean radius. A solar day differs from a sidereal rotation period.
A lighter step
Your mass would stay the same on Mars, but the downward force you feel would be about 38% of its value on Earth.
Big questions, careful answers.
Has life been found on Mars?
No confirmed discovery of life on Mars has been established. Evidence for ancient water and habitable environments motivates the search; it does not by itself demonstrate life.
Why is Mars red?
Iron-bearing minerals oxidize, creating the rusty hues of the surface and airborne dust.
Is there water on Mars today?
Yes, primarily as ice. The modern surface’s low pressure makes stable, exposed liquid water difficult to sustain. Ancient rivers and lakes belonged to different conditions.
Have humans visited Mars?
No humans have landed on Mars. Exploration has been carried out by robotic spacecraft.
A quick knowledge check
How long is a year on Mars, measured in Earth days?
Behind the numbers
Science notes are based on the sources below. Content reviewed November 3, 2026; this site does not display live mission telemetry.