In many ways Venus is Earth’s twin planet. It’s only a little smaller, and made up of the same composition as Earth. But when it comes to climate, Venus couldn’t really be more different. Venus is a hellish world – the hottest planet in the Solar System, with an average temperature of more than 400°C, and a surface pressure almost 100 times what we experience here on Earth. On top of that, there are clouds of sulfuric acid and other corrosive chemicals. Visiting Venus would be the worst vacation ever.
Before the 1960s, scientists thought that the climate of Venus might be similar to Earth. It has clouds, and here Earth, clouds mean rain, water, oceans and even life. But microwave observations of Venus showed that its surface must be incredibly hot, too hot for liquid water to exist. And spacecraft visiting the planet in the 1960s and 70s confirmed that the clouds of Venus are made up almost entirely of carbon dioxide; a potent greenhouse gas keeping the planet so hot.
But you could say that Venus has a climate. It has severe winds that blow at speeds greater than 100 m/s; although, the winds don’t reach down to the surface of the planet. It has sulfuric acid clouds which send down torrents of sulfuric acid rain.
The climate of Venus wasn’t always this harsh. In fact, Venus used to have an atmosphere similar to our own. But at some point in Venus’ past, its global magnetosphere shut down. Without this global force field, the Sun’s solar wind was able to reach the planet and tear away at its atmosphere, stripping away the lighter atoms. The lightest atom is hydrogen, of course, one of the constituents of water. Recent observations by ESA’s Venus Express showed that this process is still going on today. 2 x 1024 atoms of hydrogen are being blasted off Venus into space every second.
We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.
We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.