Head to head
Earth vs Mars
Earth and Mars are the two most-compared planets in the solar system, and for good reason: Mars is the most Earth-like world we know, with a 24.6-hour day, four seasons, polar ice caps, and a surface you could stand on. But the differences are dramatic — Mars is half Earth's size, has 1% of its air pressure, and averages -63 C.
| Property | Earth | Mars |
|---|---|---|
| Diameter | 12,742 km | 6,779 km |
| Day length | 24 hours | 24.6 hours |
| Year length | 365 days | 687 days |
| Average temperature | 15 C | -63 C |
| Atmosphere | Nitrogen + oxygen (1 bar) | Carbon dioxide (0.006 bar) |
| Moons | 1 | 2 |
| Liquid surface water | Oceans cover 71% | None today (ancient rivers/lakes) |
| Gravity | 1 g | 0.38 g |
The verdict
Mars is Earth's closest analog, but today it is a frozen desert. Its similar day length and seasons make it the most realistic target for future human exploration, which is exactly what NASA's Moon-to-Mars plans aim for.