Venus is the second planet from the sun, also the only planet in the Solar System that is named after a female figure, and the virtual twin of our planet Earth in many ways. Similar in size (its diameter is only 400mi/644km smaller than Earth), mass and density, it is relatively close to Earth (24 million miles/38million km as its closest point to Earth). Apart from the moon Venus is the brightest object in the night sky.
The planet orbits the sun at an average distance of 67 million miles/38 million km) away, every 225 days but rotates on its own axis in the opposite direction to the other planets, slower than any other in the solar system, taking 243 days compared to 24 hours on Earth, meaning a day on Venus is longer than its year.
The force of surface gravity on Venus is almost the same as the surface gravity on Earth. It is about 91% (or 12% less) of the surface gravity on our planet, so if you weight 100 pounds on Earth, you would weigh 91 pounds on Venus. But the extreme weight of atmospheric pressure would crush a human, and a spacecraft needs to shield it in order to survive. The Soviet probe "Venera" that ventured to land on the surface two decades ago did not last more than two hours before it melted down.
Venus is extremely hot, the surface temperature is a baking 465C/870F (9 times the temperatures in the hottest deserts on Earth), the hottest surface of any planet in the solar system, however, the atmospheric pressure and temperature 50 km above the surface are similar to those at Earth's surface (the temperature at the uppermost clouds of the planet average about 13C/55F).
Venus is actually a hot house planet with a runaway greenhouse effect, making it inhospitable to life. Science has not been able to develop a spacesuit that could survive more than a few minutes in its harsh environment.
Venus is surrounded by an extremely thick and reflective cloud. The reflective nature of the sulfuric acid in the atmosphere has made it impossible to see the surface from orbit without radar or radio equipment. It is so thick that most meteors could not penetrate it, burning up before impact. The atmosphere is 96% carbon dioxide and full of sulfuric acid clouds and droplets and ash from the volcanoes that dot the surface.
While there have been many large volcanoes on Earth, there is no real comparison to the number, size, and extent of the volcanic activity on Venus. Most of the surface of the planet is covered by flat plains but it also has mountains, canyons and valleys. The surface is dominated by more thousands of volcanoes, some up to 150 mi/240 km in diameter. Volcanic activity is still ongoing on the planet. Lava flows are thought to have completely resurfaced the planet between 300 and 500 millions years ago, forming huge ring-like structures dotted across its surface. These are lava domes that have flattened out over time.
The planet is named after the Roman goddess of love and beauty. The astronomical symbol for Venus is the same as that used in biology for the female sex: a circle with a small cross beneath.
Due to extremely hostile conditions, a surface colony on Venus is not possible with current technology. The atmospheric pressure approximately 50 km above the surface is similar to those at Earth's surface. In Venus's mostly carbon dioxide atmosphere, Earth's air (nitrogen and oxygen) would act as a lifting gas. This had led to proposals for "floating cities" in the planet's atmosphere. Among the many challenges are the dangerous amounts of sulfuric acid at these heights.
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