MARS

Mars / Introduction

Our next neighbor is actually the planet in the Solar System most similar to our own. Mars is named after the Roman god of war (Ares in Greek).

The men from Mars that science-fiction authors like to tell us about are often an equally aggressive lot as this Roman god and his companions. There are for example innumerable stories of Martians invading and destroying the earth.

Could there actually be life on Mars? The American P. Lowellwas convinced of this and inter-preted the channels on the planet’s surface, which were first discovered by the astronomer Schiaparelliin 1877, as parts of an artificial irrigation system. In 1976, the Viking spacecraft confirmed though that Mars does not allow for highly developed life. It even appeared that the channels were only an optical illusion. The possibility that there ever were or still are very primitive forms of life on Mars cannot be fully excluded but it is rather unlikely.

Mars is about half the size of the earth. A day on Mars is only 40 minutes longer than a day on the earth. There are distinct seasons that last approximately 6 earth months each. The maximum distance from the earth is approximately 400 million kilometers. The closest the two planets can ever be is 55.65 million kilometers apart from each other.

It takes Mars approximately 2 earth years to complete a full orbit around the sun. The climate is generally colder than that on the earth with an average temperature of minus 25 °C and a temperature range from plus 20 °C to minus 120 °C. As a consequence of the weak gravitational forces of Mars, it has only a very thin atmosphere which is unable to conserve the heat from the sun and therefore cools down quickly. The atmosphere is made up of 95% carbon dioxide.

Why does Mars appear to us as a red ball? The reason for this is the surface dust of the planet, which contains hydrated iron oxide or simply - rust.

Orbit of Mars

Our neighbor Mars is the fourth planet from the sun. Its orbit is not parallel to the orbit of the earth and this results in considerable fluctuation regarding the distance between the two planets.

They are closest to each otherwhen they are in opposition, i.e. when the sun, the earth and Mars are in one line.

Mars has a rather eccentric orbitand therefore, the distances during oppositions vary considerably. At the last aphelion (Mars at greatest distance from the sun) on February 12th,1995, the distance between Mars and the earth was approximately 101 million kilometers.

At the next perihelion (Mars at shortest distance to the sun) on August 28th, 2003, there will be "only" 55.8 million kilometers between them. When Mars and the earth are in conjunction, they are at maximum distance to each other, i.e. 400 million kilometers apart. It takes Mars just about two earth years or 687 days to complete a full orbit around the sun.

When observing Mars for a longer period, one observes that the planet seems to stop and return in the opposite direction of its normal orbit (retrograde movement). This phenomenon is caused by the different orbit velocities of the earth and Mars. During opposition, the earth ”overtakes“ Mars, which has a far greater distance to travel.

Mars Surface

The most striking feature of the surface of Mars is its red color, which can even be observed by the naked eye. The color derives from the iron compounds found in the rocks and dust of the planet. In other words, Mars is rusty.

There are various landscapes to befound on Mars. Besides areas with distinct craters and mountains, there are extensive deserts, icy polar regions, deep gorges as well as high volcanoes.

The craters were caused by meteorite impacts,which are, in contrast to the ones on Venus, partly eroded. On Mars, strong winds up to gale force were observed. These winds raise dust from the surface and make the thin atmosphere of the planet appear in a redglow. Such dust and sand storms sometimes continue for several months and, as was the case in 1971, may completely obscure the surface of Mars. The forces of erosion on Mars are very limited though compared with the ones on the earth. Mars is not exposed to the effects of plate tectonics as there are no continental plates.
The crust of Mars consists of one single plate and therefore, very large volcanoes could develop. A real giant is the volcano Olympus Mons. It is actually the highest mountain in the Solar System Its diameter is approximately 600 kilometers and its top is 27,000 meters high, which is more than three times the height of Mount Everest.Of equally impressive dimensions are the valley systems on Mars. Near the equator extends the huge plane of the Valles Marineres with gorges four times deeper and ten times longer than the Grand Canyon. Astronomers have also discovered that the weather on Mars varies according to the accompanying cloud formations, similar to the weather development on earth.Mars also has seasons.
During the Martian summer, temperatures reach a peak of over plus 10 °C. The ice on the south pole disappears almost completely. It dissipates into gas form and no water in liquid form has been found on Mars.

The shapes of existing dry river beds indicate that there was water in liquid form on Mars in the dim and distant past. It is possible that there are still permafrost layers below the surface of Mars, similar to that of our tundras.

Mars Rotation

A Martian day is 24 hours and 37 minutes long. This is the time it takes Mars to complete a full rotation on its own axis. The axis of rotation is inclined towards the orbit plane by 24 degrees, which is very similar to the inclination of the earth’s axis (difference of 1.7 degrees).

It is this inclination of the axis that results in the different seasons that can be observed on Mars. Certain areas are at certain timesmore exposed to or shaded fromthe direct light of the sun .

As Mars has a longer orbit cycle than our planet, the Martian seasons are approximately double those of the earth. One Martian year equals 687 earth
days.