- Named after the Roman god of war
- Often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance
- Mars is the site of Olympus Mons, the highest known mountain in the Solar System, and of Valles Marineris, the largest canyon
- Approximately half the radius of Earth
- Has two permanent polar ice caps
- Atmosphere is 95% carbon dioxide, 3% nitrogen, 1.6% argon, and contains traces of oxygen and water