Mars, the fourth planet from the Sun, is commonly referred to as the Red Planet due to its reddish appearance from Earth. The planet is named after the Roman God of War, Mars. It is the seventh largest planet in our solar system. The yellow-orange color of the Martian surface is due to the presence of oxidized iron in the regolith. The pink-orange color of the sky is caused by extremely fine red dust that is suspended in the thin atmosphere of Mars.
Start playing the below astronomical video to see the surface of the planet Mars. The video was created with the aid of the virtual reality astronomy program VRMars-Spirit - The Red Planet Mars 3D, presenting the Mars Exploration Rover Spirit Mission.
Mars is 4220 miles (6791 km) in diameter (Earth - 7926 miles). It has one-tenth the mass of Earth, being less dense, however, its surface area is only slightly less than the total area of Earth's dry land. Gravity is 0.38 that of Earth, which means that if you weigh 100 pounds or kg on Earth, you would weigh 38 pounds or kg on Mars. Gravity is one of the problems future human missions to Mars will have to deal with, since living in a low-gravity environment will cause problems for human health. The red planet has seasons like Earth does. It is a cold planet. The temperature on Mars can drop to as low as 140 Kelvin (-133 degrees Celsius, or -207 degrees Fahrenheit). Occasionally at the equator the temperature of the surface can rise to above the melting point of ice (273 Kelvin, 0 degrees Celsius, or 32 degrees Fahrenheit). The average surface temperature on Mars is about 210 Kelvin (-63 degrees Celsius, or -81 degrees Fahrenheit). Due to great temperature variations occasionally vast dust storms occur on Mars that can cover almost the entire planet. One of such dust storms happened during the Mars Exploration Rover Mission. Mars rovers Spirit and Opportunity hardly survived that harsh environment.
The Martian day (sol) is similar to that of Earth. It is only 41 minutes longer than the day on Earth. The planet Mars is not a pleasant place to live. It is believed that early in its history, Mars was much more like Earth. Both rovers, Spirit and Opportunity, provided evidence that liquid water once existed on the surface of Mars. It is highly probable that at some time in the past there were rivers, large lakes or even oceans on Mars. Martian atmosphere is quite different from that of Earth. Pressure is very low, more than a hundred times lower than on Earth. The main component of the atmosphere is carbon dioxide (95.32%). There is almost no oxygen (only 0.13%). Due to a thin atmosphere and weak magnetosphere (Mars Global Surveyor discovered quite large, weak magnetic fields in various regions of Mars) future manned missions to Mars will have to deal with a cosmic radiation. However, the atmosphere is thick enough to support strong winds, which surprisely helped Mars rovers to blow away the dust from the solar panels during long Mars Exploration Rover Mission. Martian air contains only 0.03% of water vapour, which is about 0.001 that of Earth, but even this small amount can condense out, forming clouds and covering the surface with water frost. There may also be water ice hidden below the surface and in polar caps. The planet has permanent ice caps at both poles composed mostly of solid carbon dioxide (so-called "dry ice"). Mars probably lacks active plate tectonics. There is no evidence of current volcanic activity. There is also no evidence that life ever existed on Mars. Some scientists claim that they found such evidence, fossil life, in the Martian meteorite ALH 84001. Scientific world is divided, but certainly there is no hard evidence now. It is possible that soon the Phoenix Mission to Mars will provide more clues regarding this issue.
Below there are some quick facts on the planet Mars.
QUICK FACTS on MARS
Moons:
Phobos - diameter 13.7 miles (22 km), orbit 3716 miles (5981 km) from the surface of Mars
Deimos - diameter 7.5miles (12 km), orbit 12466 miles (20062 km) from the surface of Mars
Mass: 6.4185E+23 kg (0.10744 that of Earth)
Density: 3.94 g/cm3 (0.714 that of Earth)
Equatorial surface gravity: 12.116 ft/s2 (3.693 m/s2, 0.38 that of Earth)
Escape velocity: 11229 mph (18072 km/h, 0,448765 that of Earth)
Equatorial radius: 2111 miles (3397 km, 0.5326 that of Earth)
Diameter: 4220 miles (6791 km)
Surface area: 89500000 square miles (144100000 km2, 0.282 that of Earth, about the same as the land area of Earth)
Minimum surface temperature (winter pole): 140 K (-133 deg. Celsius, or -207 deg. Fahrenheit)
Mean surface temperature: 210K (-63 deg. Celsius, or -81 deg. Fahrenheit)
Maximum surface temperature (summer dayside): 300 K (27 deg. Celsius, or 81 degrees Fahrenheit)
Martian day (sol): 24 hours, 37 minutes 22 seconds
Martian year: 686.98 Earth days, 669 Martian days (sols)
Average distance from the Sun: 141633260 miles (227936640 km, 1.523662 AU, 1.524 that of Earth)
Perihelion (closest distance from the Sun): 128402967 miles (206644545 km, 1.381 AU, 1.404 that of Earth)
Aphelion (farthest distance from the Sun): 154863553 miles (249228730 km, 1.666 AU, 1.638 that of Earth)
Equatorial circumference: 13263 miles (21344 km)
Mean orbital velocity: 53979 mph (86871 km/h, 0.810 that of Earth)
Equatorial inclination to orbit: 25.19 degrees
Orbital inclination to ecliptic: 1.85061 degrees
Atmospheric pressure at surface: 6.35 mbar (Earth - 1013 millibars at sea level)
Atmospheric Composition:
Carbon Dioxide: 95.32%
Nitrogen: 2.7%
Argon: 1.6%
Oxygen: 0.13%
Carbon Monoxide: 0.07%
Water vapor: 0.03%
Nitric Oxide: 0.013%
Neon: 0.00025%
Krypton: 0.00003%
Formaldehyde: 0.000013%
Xenon: 0.000008%
Ozone: 0.000003%
Methane: 0.00000105%
Start playing the below astronomical video to see the surface of the planet Mars. The video was created with the aid of the virtual reality astronomy program VRMars-Spirit - The Red Planet Mars 3D, presenting the Mars Exploration Rover Spirit Mission.
