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About Mars: General Information | How was Mars discovered? | Geological History | Ancient Mythology
The atmosphere of Mars consists of gases that are also found in Earth's atmosphere, though at different proportions:
| Gas | Percentage in the atmosphere of Mars |
|---|---|
| Oxygen | 0.13% |
| Water vapour | 0.03% |
| Nitrogen | 2.7% |
| Argon | 1.6% |
| Carbon monoxide | 0.08% |
| Carbon dioxide | 95.32% |
There is no ozone layer in Mars' atmosphere, thus, the extra radiation coming in from the Sun can kill living things. Due to dust storms, Mars' sky is pink in colour. Its atmosphere is also much thinner than Earth's therefore, making it difficult to breathe.
Mars is half the size of Earth and its axis tilts at an angle of about 24 degrees. Its surface is reddish in colour due to he presence of oxides of iron, which essentially is rust.
The following are the statistics of Mars:
| Type of information | Data |
|---|---|
| Mass | 6.42 * 1023kg |
| Diameter | 6787km |
| Density | 3940kg m-3 |
| Escape velocity | 5000m s-1 |
| Distance from the Sun | 227,900,000km |
| Length of day | 1.026Earth days |
| Length of year | 686.98Earth days |
| Inclination of equator | 25.2Degrees |
| Orbit inclination | 1.85Degrees |
| Mean orbital speed | 24.1km s-1 |
| Polar radius | 3375km |
| Volumetric mean radius | 3390km |
| Surface gravity | 3.71m s-2 |
| Surface pressure | 6.36millibars at mean radius |
| Topographic range | 30km |
| Number of satellites | 2 |
Orbital eccentricity relates the shape of the path of Mars' orbit around the Sun. A circle has an eccentricity of zero, and a larger number means it is more elliptic. Orbital inclination is the tilt of the planet's orbit in relation to the ecliptic plane .Earth's orbit defines the ecliptic plane. Mars approaches nearest to Earth every two years and two months.
Mars has 4 seasons, just like the Earth. They are, namely, spring, summer, autumn and winter. This is because of its axial tilt and sicne Mars' tilt is similar to that of Earth, so are its seasons. As Mars takes more time to revolve around the Sun, its seasons are nearly twice as long as that of Earth's. Temperatures can be very extreme on Mars ranging from -225°F in autumn and winter to 65°F in spring and summer. Violent dust storms can occur on Mars and their speeds can go up to about 100km/h. They carry tons of dust with them and can sometimes cover the whole planet with dust. Unlike sandstorms on Earth, the dust has the consistency of flour.
| Northern Hemisphere | Southern Hemisphere | Length in Earth Days |
|---|---|---|
| Spring | Autumn | 199 |
| Summer | Winter | 183 |
| Autumn | Spring | 147 |
| Winter | Summer | 158 |
Mars is named after the Roman war god. Its satellites are named after the sons of the Greek war god, Ares who is a counterpart to Mars. They are named Phobos and Deimos which mean fear and panic respectively. Phobos is much closer to Mars than Deimos and is the only known moon that circles its parent planet in less time than it takes that planet to complete one revolution about its axis. Both moons are heavily cratered with Phobos being 28km in length and Deimos being 16km in length. Both are thought to be asteroids captured by the gravity of Mars.
| Phobos | Deimos | |
|---|---|---|
| Semi-major Axis | 9,400km | 23,500km |
| Period of Orbit | 7hr 39min | 30hr 18min |
| Diameter | 23km | 13km |
| Mass | 1 * 1016kg | 1 * 1015kg |
| Orbital inclination | 1.08degrees | 1.79degrees |
| Average Density | 2.0g cm-3 | 1.7g cm-3 |
A third of the surface of Mars appears as dark areas and they change colour and size with the Martian seasons. Scientists believe this is due to the fact that some kind of vegetation exist in these areas. The polar caps are thought to be either ice (solid water) or dry ice (solid carbon dioxide). The size of each polar cap varies with the year. A cap will increase in size when it is tilted away from the Sun and vice versa.
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