Enigma of Venus

The surface of Venus is covered with lava cooled.
This reconstruction of computerized surface of Venus was created from data from the Magellan probe with its radar altimeters set to radio wavelengths, which the Venusian clouds are transparent.
Magellan turned around Venus for 4 years and has used its radar to map the planet from 1990 to 1994.
Magellan found many interesting structures on the surface of Venus, with large circular domes, typically 25 km in diameter (image opposite).
Volcanism appears to be the cause of these domes, although the mechanism remains unknown.
The surface of Venus is so hot and hostile that no surface probe has survived no more than a few minutes.

The sister planet Earth, periodically close to 40 million km, although made of the same mixture of rock, not like at all to the Earth.
Venus is the hottest in the solar system.
She suffers from an extreme greenhouse effect, the sky is covered at all times. Venus appears to have been fully covered by lava at some point in his life. Everywhere on Venus there is lava, volcanic everything. The atmosphere of Venus is extremely busy in CO2, infrared and heat are trapped at the surface is so intense (470 ° C), no form of life as we know, can not develop there.
For a long time, Venus remained opaque, even with the largest telescopes can not see anything of its surface covered with a thick layer of cloud.
It was not until 1962 that it is discovered that Venus rotates on its axis very slowly. Its sidereal rotation period of about 243 Earth days, the more it is done in the opposite direction, with only planet Uranus have retrograde rotation.
Atmosphere rotates much faster in 4 days.
Venus being closer to the Sun than the Earth, solar radiation accelerated the runaway greenhouse effect. Venus has gradually developed a thick, hazy atmosphere. Volcanoes have generated a large amount of carbon was mixed with oxygen until there is more than just CO2. The Magellan spacecraft between 1989 and 1994, will provide us with real images of Venus by placing in orbit around Venus.

Its radar is sweeping the entire surface of Venus converting radar data in pictures.
The planet will become visible to humans.
Magellan discovered a thousand large meteorite craters. There are very few small craters, below a few km in diameter.
The dense atmosphere of Venus filter small meteorites that below a certain size, are consumed.
In addition, the number of craters tell us about the age of the craters, some cratered surface is generally younger. The density of meteorite impacts is the same over the entire surface of the planet.
This means that the craters are less than a billion years and the traces of old craters have been erased.
This proves that there was a significant volcanic activity, there are about 500 million years.
No smoking cone was observed, it seems that there is no volcanic activity today. All reliefs, except for the relief of Mount Maxwell, have women's names (Eve, Helen, Cleopatra, Ishtar, Leda, Aphrodite, Diana, Inanna (Babylonian goddess of fertility...).
Astronomers believe that there are from time to time, major disasters, long periods of intense volcanic activity, which erase the traces of ancient impacts.
For lack of water, plate tectonics on Venus is seized, but Venus in the bowels of the heat will eventually be expelled to the surface.
If no volcanic flow has been detected so far, the next could indicate the onset of a giant cataclysm.