Bob the Alien's Tour of the Solar System
Bob the Alien's Tour of the Solar System

Venus' Poisonous Atmosphere


Venus is the closest planet to Earth and one of the brightest objects in the sky after the Sun and the Moon. It has been observed for many thousands of years, with many people believing that it could be another Earth.

From Earth, Venus appears to be a beautiful planet and is even named after the Roman goddess of love and beauty. As astronomers became able to get a closer look at Venus with telescopes, they discovered that it appeared to be covered by clouds.

As the space age began in the 1960s and scientists became able to send objects into space and to other planets, one of the first ones they wanted to study was Venus. Not just because it is quite close to Earth (in space terms anyway), but because it was a chance to find out finally what secrets this beautiful planet was hiding under its cloud cover. Did Venus have hills and mountains, lakes and oceans, valleys and volcanoes? Were there even signs of life on the planet? Some people imagined that Venus, being closer to the Sun and therefore warmer, could possibly be a tropical paradise.

It turned out that Venus is probably the last place in the Solar System you'd ever want to visit. Venus' clouds are very thick. It is totally impossible to see through them to observe the surface of Venus. The only way of doing so is either to travel through the clouds and land on Venus' surface, or use special equipment that can map the surface with radar while orbiting the planet. The safest option is to map the surface from space because, not only are Venus' clouds very thick, they are also extremely deadly. No human being would ever travel to the surface of Venus. In fact, most space craft that have tried to do so have only lasted a few minutes after landing before being destroyed by the planet's conditions.

Venus receives heat from the Sun, but, because of its thick cloud cover, the heat is trapped under the cloud, unable to escape back into space as it does on Earth. This is similar to how a greenhouse works on Earth. Temperatures at Venus' surface are on average 864 °F / 462 °C. The makes Venus the hottest planet in the Solar System, even hotter than Mercurywhich is closer to the Sun.


Diagram showing greenhouse effect on Venus

The cloud that covers Venus is not like the cloud in the skies on Earth. It is full of deadly sulphuric acids droplets, not water droplets as on Earth. Nearly all of Venus' atmosphere is made up of carbon dioxide, a poisonous, suffocating gas which would kill any living creature if it was breathed in. Earth atmosphere is made up of nitrogen and oxygen. Since the 1970s, missions to Venus have set out to discover what lies under its mysterious and deadly cloudy cover, the most successful being the Magellan radar mapping mission from 1990 to 1994 and Venus Express from 2005 to 2014. These missons have enabled maps to be generated of Venus' surface and landscape. You can find out about Venus' surface here.

Bob the Alien's Tour of the Solar System
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