Mars It is the fourth planet of the Solar System. Known as the red planet by its pink tones, the Romans identified it with blood and named it after their god of war.

When it is closer to Earth, about 55 million kilometers away, Mars is, after the Moon, Venus and Jupiter, the brightest object in the night sky. It can be seen more easily when the straight line Sun-Earth-Mars is formed (that is, when it is in opposition) and is close to Earth, which happens once every 15 years. It happened for the last time on July 31, 2018, when he was seen in the constellation of Capricorn.

The following table shows data from Mars comparing them to Earth:

Basic dataMarsThe earth
Size: equatorial radius3,390 km.6,371 km.
Average distance to the Sun227,937,000 km.149,600,000 km.
Day: period of rotation on the axis 24.62 hours23.93 hours
Year: orbit around the Sun686.98 days365,256 days
Average surface temperature-46 º C15 º C
Surface gravity in the equator3.71 m / s29.78 m / s2

Because of the inclination of its axis and the eccentricity of its orbit, Martian summers are short and hot, while winters are long and cold. Huge shiny caps, apparently formed by frost or ice, indicate the polar regions of the planet.

Like Earth, Mars has in its center a dense metal core covered by layers of lighter materials. Around the planet two natural satellites, Phobos and Deimos, rotate in orbits, much smaller than our Moon.

There is life in Mars? Can there be?

Before space exploration, it was thought that there could be life on Mars. So far, the observations have failed to show if he has it, although he could have had it in the past.

Under current conditions, Mars is sterile, it cannot have life. Its soil is dry and oxidizing, and it receives too many ultraviolet rays from the Sun. However, it had a great ocean millions of years ago and traces of methane have been detected, although it is unknown if it is of geological or biological origin.

In 2018, a lake of liquid and salt water was discovered under the ice of the South Martian pole. This encouraged the debate about life on Mars and if you could terraform the planet, changing its conditions to make it habitable. For now there is only speculation and abundant science fiction.

The atmosphere of Mars

Mars has a very fine atmosphere, formed mainly by carbon dioxide, which freezes alternately at each of the poles. It contains only 0.03% water, a thousand times less than Earth. But the red planet had a more compact atmosphere before, with clouds and rainfall that formed rivers. On the surface it guess furrows, islands and coasts.

The seasonal cycle of Mars has been followed for almost two centuries. In the Martian autumn bright clouds form on the corresponding pole. A thin layer of carbon dioxide is deposited on the polar cap during the fall and winter, at the end of which the polar ice can descend to latitudes of 45 °. In spring and at the end of the long polar night, the seasonal part is falling apart and shows the frozen winter cap, which is permanently maintained.

In addition to clouds of frozen carbon dioxide, on the planet Mars there are other types of clouds. For example, fogs and ice clouds are observed at high altitude. The latter are the result of the cooling associated with the masses of gases that rise above elevated obstacles. Extensive yellow clouds composed of dust raised by winds are especially noticeable during the southern summers.

The surface of Mars

Mars is a rocky planet, made up of minerals that contain silicon, oxygen and some metals. On its surface, impact craters similar to those of the Moon are observed, but it also has volcanoes, mountains, valleys and deserts similar to those on Earth.

The reddish hue of Mars is due to oxidation or corrosion. The dark areas are formed by rocks similar to terrestrial basalt, whose surface has been eroded and oxidized. The brightest regions appear to be composed of similar material, but contain finer particles, such as dust.

The large temperature differences cause very strong winds. In addition, the erosion of the Martian soil helps to form dust and sand storms that further degrade the planet's surface.

In the Astronomy History section there is a whole chapter dedicated to the Mars planet exploration. You may also be interested in an image gallery that contains 16 commented photos of Mars.

Discover more:
• The Planet Mars according to Wikipedia
• Methane in the atmosphere of Mars
• NASA in Spanish: missions to Mars

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Phases of the Moon and eclipsesThe 2 satellites of Mars