The planet Venus is the second planet closest to our Sun. Mercury is closest, Venus is next, Earth is the third, and Mars is the fourth planet from our Sun.
This means that Venus is considered to be one of the three planets in our solar system located in what is called the habitable zone, along with Earth and Mars. Because of their distance away from the Sun, it was thought that maybe the environment on Venus and Mars might be capable of supporting life, like it is on Earth.
Venus is about 67.2 million miles (108.2 million km) from the Sun. In contrast, Earth is about 93 million miles (150 million km) away from the Sun (Head, 2004).
In addition, Venus is about the same size and has almost the same density, and surface gravity as that of Earth. The internal structure of Venus is also thought to be similar to that of Earth. Scientists believe that Earth and Venus formed at about the same time (4.6 billion years ago).
Unfortunately, as it turns out, conditions on Venus are not Earth-like. Conditions on Venus are much too hot, at least for organisms like ourselves.
Venus is covered by a dense atmosphere of sulfuric acid clouds. Sulfuric acid is the major component of battery acid. There is frequent lightning on Venus that is associated with these clouds.
These thick sulfuric acid clouds and greenhouse gases on Venus prevent heat from escaping so the environment is very hot. In fact, the surface temperature on Venus reaches well over 800 °F (427 °C).
Because of the thick clouds, scientists have a hard time imaging the surface of Venus. In the past, a couple of Soviet robotic spacecraft landed on the surface of Venus, but lasted only about an hour in the harsh environment before being destroyed.
However, the NASA Magellan spacecraft was able to map out the planet's surface in some detail.
Venus shows evidence of a lot of volcanic activity and the surface has lots of lava rilles (canyons or ditches caused by flowing lava). Venus' surface has some impact craters, but not a lot of them. Venus may not have many impact craters for two reasons:
- Small meteors burn up on the way in because of the thick atmosphere;
- Most impact craters have been erased from the surface by recent lava flows.
Most of the surface, is dry, flat, and rocky.
Most of the volcanoes on Venus are shield volcanoes. These volcanoes are not associated with tectonic plate boundaries, but form when hot lava comes up through the planet's crust. The presence of lava domes, as shown in the black and white photo, indicates the presence of a high silica content on the planet.
Scientists are uncertain whether or not Venus is currently undergoing volcanic activity.
The atmosphere on Venus consists mainly of carbon dioxide (about 97%) and a small amount of nitrogen gas. There are a few trace amounts of other gases present as well (e.g., argon, water vapor, oxygen, carbon monoxide). As mentioned earlier, the clouds on Venus consist of sulfuric acid and some sulfur dioxide.
In addition, the atmospheric pressure is about 90 times greater on Venus than on Earth.
Scientists believe that millions of years ago the atmosphere on Earth and Venus was similar to one another, but the planets' atmospheres evolved differently.
For example, on Earth most of the carbon dioxide dissolved in our oceans and the remaining carbon dioxide combined with other molecules on our planet. If this hadn't happened then Earth would most likely be an oven like Venus is. Carbon dioxide is a greenhouse gas and traps in solar radiation and heat from the Sun.
It is possible that oceans didn't form on Venus like they did on Earth because Venus is closer to the Sun. Because there were no oceans on Venus for most of the carbon dioxide to dissolve in, the carbon dioxide remained in the atmosphere.
There is no evidence of large amounts of water on Venus, now or in the past. Because of the extremely high temperatures any water that was present would evaporate, however, there doesn't seem to be much water vapor on Venus either.
The length of a day on Venus is much different than that on Earth. It takes Venus 243 days to make one full rotation on its axis.
Venus has no magnetic field and no moon.
Head, James W., III. "Venus." World Book Online Reference Center. 2004. World Book, Inc. http://www.worldbookonline.com/wb/Article?id=ar582880.
Image of Venus: Courtesy of NASA Jet Propulsion Laboratory.
Image of Venus surface and lava domes: Courtesy of NASA Johnson Space Center.