- MEAN RADIUS: 3388.0 km
- MASS: 0.108 (Earth=1)
- DENSITY: 3.94 (g/cm^3)
- GRAVITY: 0.380 (Earth=1)
- ORBIT PERIOD: 686.98 (Earth days)
- ROTATION PERIOD: 1.026 (Earth days)
- SEMIMAJOR AXIS OF ORBIT: 1.524 au
- ECCENTRICITY OF ORBIT: 0.093
The density of Mars is about 30 percent less than that of Earth (3.94 g/cm3 vs. 5.52 g/cm3). Its core is probably similar to Earth's, mostly iron, with small amounts of nickel, but spacecraft mapping of its gravity field seem to indicate that its iron-rich core and mantle are a smaller portion of its volume than on Earth. Also, Mars' smaller magnetic field than Earth, indicates a solid, rather than liquid core.
Mars' atmosphere is 95 percent carbon dioxide, nearly 3 percent nitrogen, and nearly 2 percent argon with trace quantities of oxygen, carbon monoxide, water vapor, ozone, and other trace gases.
The average temperature on Mars is about -55 C or -67 F. It can range from -133 C or -207 F at the winter pole to almost 27 C or 80 F on the day side during summer. Orbiting 227,940,000 km (1.52 AU) from Sun, the Martian year is nearly two Earth years, while a day on Mars is only about half an hour longer than Earth's.
Mars has two tiny satellites which orbit very close to the surface:
Distance(000km) 9 - Radius (km) 11 - Mass (kg) 1.08e16 - Discovered By & Year Hall 1877
Distance(000km) 23 - Radius (km) 6 - Mass (kg) 1.80e15 - Discovered By & Year Hall 1877