Mars

Mars

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Mars in Greek is Ares which is the god of War. The planet is sometimes referred as the Red Planet. The planet probably got its name due to its red color. The name of the month March derives from Mars.

Mars has been known since prehistoric times. It is a favorite of science fiction writer as the most inhabitable place in the solar system outside of the Earth. The famous "canals" "seen" by Percival Lowell and others were just imaginary as Barsoomiam princess.

Mars is the fourth planet in order of distance from the Sun and the seventh largest:
orbit: 227.940.000 km (1.52 AU)
diameter: 6794 km
mass:

The first spacecraft to visit Mars was Mariner 4 in the year 1965. Several others followed including the two Viking probes in 1976. At last after long 21 year hiatus, Mars Pathfinder landed successfully on Mars on July 4th 1997.

Mars´ orbit is significantly elliptical. One of the result of this is a temperature variation of 30°C at the subsolar point between aphelion and perihelion. This has great influence on Mars´ climate. Mars´ average temperature is about -55°C to -67°C. The average temperature range widely from as low as -133°C at the winter pole to about freezing point at the summer on the dayside during summer, it may never rise above zero.

Mars is only half the size of the Earth. But Mars´ surface is about the same as the land surface area of Earth

Mars is, except for the Earth, mostly highly varied and interesting terrain of the terrestrial planets, some of them are extraordinary. For example the Olympus Mons is the largest mountain in the solar system. It rises 25 km above the surrounding plain, it is a shield volcano, its base is more than 500 km in diameter and is rimmed by a cliff of 6 km high. The Tharsis is a huge bulge on the Martian surface that is about 10 km high and 4000 km across. Valles Mariners is a system of canyons that is 4000 km long and 2 to 7 km deep. Hellas Planitia is an impact crater in the southern hemisphere over 6 km deep and 2000 km in diameter

The Martian surface is very old and very cratered, but there are many ridges, hills and plains, and rift valleys that are much younger.

Martian southern hemisphere is very cratered, not unlike the Moon´s surface. But most of the northern hemisphere consists of plains which are much younger, they are lower in elevation and have a more complex history.

Mars´ interior is known only by inference from data about the surface and the bulk statistics of the planet. The most likely scenario is very dense core which is about 1700 km in radius. A molten rocky mantle somewhat denser than the Earth´s but a thin crust. Mars´ relatively low density compared to other planets. That indicates that Mars´ core contains a relatively large fraction of sulphur in addition to iron.

On Mars are many clear evidence of erosion in many places, including small river and large floods. Water was there clearly some time in the past, there may have been some large lakes or even oceans. It seems that this occurred only briefly and very long ago. The age of erosion channels is estimated at about nearly 4 billion years.

The great Valles Mariners was not formed by running water. It was formed by the stretching and cracking of the crust associated with the creation of the Tharsis bulge.

The atmosphere of Mars is very thin. It is mostly composed of the tiny amount of carbon dioxide, nitrogen, argon, traces of oxygen and water vapour. The average pressure on the surface of Mars is only about 7 millibars or 1% of Earth´s. It varies greatly with altitude from almost 9 millibars in the deepest basins to about 1 millibar at the top of Olympus Mons. Though Mars´ atmosphere is so thin it is thick enough to support very strong winds, vast dust storms that engulf the entire planet for four months. Here below is a list of the matters in Mars´s atmosphere:

   Carbon Dioxide = 95.3%
               Nitrogen = 2.7%
                   Argon = 1.6%
                 Oxygen = 0.15%
                    Water = 0.03%

Mars has permanent ice caps at both poles, composed mostly of solid carbon dioxide which is called "dry ice".

Conditions on Mars may not have been typical when the Viking probes visited Mars, recent observations with the Hubble Space Telescope reveled that. Mars´ atmosphere now seems to be both colder and dryer than measured by the Vikings.

A Small number of meteorites found on the poles, the SNC meteorites, are belived to have originated on Mars.

One Martian year is 687 Earth days or almost one year longer than the Earth´s. One Martian day is slightly longer than Earth´s, or 24 hours 37 minutes and 22.6 seconds. So one Martian year is 668 sols.

Mars has large, but not global, and weak magnetic field that exist in various regions of Mars. This was an unexpected finding made by Mars Global Surveyor just few days after it entered Mars orbit. Tey are probably remnants of an earlier global field that has since disappeared. This may have important implications for the structure of Mars´s interior and for the past history of its atmosphere and hence for the possibility of ancient life.

At nearest to us Mars may come within 59 million km of the Earth. Nearer than any other planet appart from Venus. When it is in the nightime sky, Mars is easily visible with the naked eye. At brightest Mars will become very bright redish object with a magnitude of -2.8. Small telescopes can show considerable surface details like: the ice caps, Syrtis Major and even the great Velles Mariners.

Mars has two tiny satellites which orbit very close to the surface. They were probably asteroids that Mars captured long time ago. Their name is Phobos and Deimos and were both discovered by Asaph Hall in the year 1877, with the large refractor at Washington Observatory.