The red planet, Mars, is the planet most similar to Earth, but it is much colder, has a very thin atmosphere, and contains very little water. However, there is evidence that it had much more water in the past, and in liquid form, prompting speculation that there may have been some form of life on Mars.
Picture: Hubble Space Telescope,
March 7, 1997
| Semi-major axis | 1.52AU |
| Eccentricity | 0.09 |
| Orbital period | 1,88 year |
| Orbital speed | 24 km/s |
| Inclination to ecliptic | 2 deg |
| Mass (x mass of Earth) | 0.11 |
| Radius (x radius of Earth) | 0.53 |
| Density | 3.9 x 10^3 kg/m^3 |
| Length of day | 24.6 days |