General
- One of the five planets known to the ancients; Mars was the Roman god of war, agriculture, and the state.
- Mars has a reddish color, and at times is the third brightest object in the night sky. (The Moon and Venus are first and second, respectively.)
Physical Characteristics
- Average Diameter = 6,780 km; about half the diameter of Earth, and twice the diameter of the Moon.
- Mars has the same land area as Earth; that is, the surface area of Mars is approximately equal to the land area of the Earth.
- Mass = 6.4219 x 10 23 kg.
- Average Density = 3933 kg/m3.
- Equatorial Radius = 3397 km.
- There is no planet-wide magnetic field detected, there are only localized ancient remnant fields in various regions.
Orbit
- Mars is the fourth planet from the sun, the next beyond Earth.
- Mars is about 1.5 times as far from the sun as the Earth is.
- Its orbit is elliptical, its distance from the sun varies from 206.7 million km to 249.2 million km. Its average distance from the sun is 227.7 million km.
- It revolves around the sun once every 687 Earth days, so a Mars year is 687 Earth days.
- A Mars day is 24 hours, 37 min, 23 sec, or 1.026 Earth days.
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Environment
- The atmosphere is composed chiefly of carbon dioxide (95.3%), nitrogen (2.7%) and argon (1.6%).
- The atmospheric pressure is less than 1/100th that of Earth.
- Surface winds can be up to 40 m/s (80 miles/hour).
- There are local and regional dust storms, called whirlwinds or dust devils.
- The surface temperature averages -53 °C (-64 °F) and varies from -128 °C (-199 °F) to 27 °C (80 °F).
Features
- The highest point on the planet is Olympus Mons, a huge shield volcano about 26 km (16 miles) high and 600 km (370 mi) across, about the same area as Arizona.
- The canyon system of Valles Marineris is the largest and deepest known in the solar system. It extends more than 4,000 km (2,500 miles) and reaches depths of 5 to 10 km (3 to 6 miles) from the surface.
Moons
- Mars has two irregularly shaped moons, Phobos and Deimos.
- The larger moon, Phobos ("fear"), and the smaller moon Deimos ("terror"), named for attributes personified in Greek mythology as sons of Ares, the god of war.
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| Parameter |
Mars Value |
Earth Value |
Units |
|---|
| Mass |
6.42 x 10^23 |
5.98 x 10^23 |
kg |
| Diameter |
6,787 |
12,756 |
km |
| Average distance from the sun |
1.524 |
1 |
AU |
| Maximum surface temperature |
310 |
310 |
K |
| Minimum surface temperature |
150 |
260 |
K |
| Mean density |
3.94 |
5.52 |
g/cm^3 |
| Escape velocity |
5.03 |
11.20 |
km/s |
| Rotational period |
24.6229 |
23.93 |
Earth Hours |
| Revolution period |
686.98 |
365.26 |
Earth Days |
| Axis tilt |
23.4 |
25 |
Degrees |
Atmospheric Components
| Element |
Symbol |
Percentage |
|---|
| Carbon Dioxide |
CO2 |
95.32 |
| Nitrogen |
N2 |
2.7 |
| Argon |
Ar |
1.6 |
| Oxygen |
O2 |
0.13 |
| Carbon Monoxide |
CO |
0.07 |
| Water |
H2O |
0.03 |
| Neon |
Ne |
0.00025 |
| Krypton |
Kr |
0.00003 |
| Xenon |
Xe |
0.000008 |
| Ozone |
O3 |
0.000003 |
Phobos and Deimos - the Moons of Mars
| Phobos | Deimos |
|---|
| Distance from Mars |
9380 km (5830 miles) |
23,500 km (14,600 miles) |
| Period of revolution |
7.6 hrs |
30 hrs |
| Escape velocity |
7.8 m/s (25.7 ft/s) |
4.7 m/s (15.5 ft/s) |
| Dimensions |
25 km (16.7 miles), long axis |
13 km (7.5 miles), long axis |
| Reflectivity |
0.5 |
0.5 |
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