Venus
After Mercury, we come to Venus at a distance of about 0.72 astronomical units from the Sun (108 million kilometers). View from the earth, Venus is never far away from the Sun, with an angular separation of a maximum of 45 degrees.
Venus is one of the most interesting objects to observe because, due to its revolution around the Sun, the planet has a moon as the visible phases of cycle using simple binoculars. In addition, when the revolution brings relatively close to Earth, Venus is the brightest object in the sky after the Sun and Moon.
the orbit of Venus
The last transit of Venus this century occurred between 5 and June 6, 2012. This image shows the transit of Venus across the Sun as the recorded satellite SDO (Solar Dynamics Observatory). The space observatory SDO was launched in 2010 by NASA to study the Sun, but has also been involved for this very special occasion. The images were taken in the far ultraviolet, usually used to study the solar corona. For patients and optimistic people, the next transit of Venus will occur in 2117.
Venus is similar to Earth from the perspective of the size (12 100 kilometers in diameter), mass and chemical composition. The most apparent difference is its external appearance. In contrast to our planet, Venus has a completely opaque atmosphere that prevents us to observe its surface.
This barrier was a major obstacle in the study of the planet. Thus, the rotation period was unknown until the early 1960s, when astronomers made use of a radar to measure it. They then discovered that Venus differs from other planets by a reverse rotation of the normal and a very long period of about 243 Earth days.
Venus really began to be studied with the advent of the space age. She was the first planet in the solar system to be flown by a probe in this case Mariner 2 in 1962. A whole armada of probes followed, first other US missions Mariner, who flew over the planet, and several Soviet probes Venera and US Pioneer Venus Multiprobe which plunged into the atmosphere and landed on the surface.
Finally arrived Pioneer Venus Orbiter, other Venera probes, Magellan and the American mission, which began orbiting the planet and were able to map its surface with radar.
The surface of Venus
Venus topography was unveiled we mainly probes that are placed in orbit around the planet and have explored using radars. First it was Pioneer Venus Orbiter, and several Venera probes, and finally the Magellan mission to meticulously mapped 98 percent of the surface of the planet in several years, with a resolution of about 100 meters.
The probes revealed that the surface of Venus is globally dominated by vast plains. The monotony is broken, however, by two huge highland areas the size of a continent, called Aphrodite Terra and Ishtar Terra.
The soil of Venus photographed by the Soviet probe Venera 13 in 1982
The Venusian landscape is in turn dominated by volcanic formations. Many volcanoes are visible, especially with Maxwell Montes, which rises to 11 km altitude.
There are also strange dome-shaped pancake, probably due to a very viscous lava, and many traces of ancient lava flows.
Everything seems to show that in fact the planet Venus has been very active volcanic view until very recently, perhaps only 10 million years BC. The probes have revealed, however, no activity at present and did not detect any trace of plate tectonics like Earth.
In addition to the volcanic formations, another important feature is the presence of many craters, all of diameter greater than several kilometers, evidence that the atmosphere dense with shattered all meteorites low size.
Finally, the appearance of the surface was revealed by some photographs by Venera probes which are laid gently onto the ground. These images show deserts and rocky landscapes, appearing orange because of the atmosphere of Venus.
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