Venus: The planet where it rains acid

Venus in visible light | Image: Wikipedia

Everyone seems to complain whenever it rains here on Earth, but on Venus you might actually have good reason to moan. Instead of water Venus’s clouds are made of corrosive sulfuric acid, and if you got covered in that, chances are you wouldn’t be around very long to tell the tale.

In reality it never rains sulfuric acid (at least not down to ground level) on Venus, because it evaporates before it has time to hit the ground – in fact, surface temperatures on Venus are hot enough to melt lead.

New research from ESA’s Venus Express probe is starting to reveal some of the secrets of Venus’s atmosphere, and some of them are very surprising indeed.

Unlike on Earth, where clouds tend to move only a few hundred miles at most, sulfuric acid clouds on Venus have ben seen moving from the poles to the equator, then back to the poles again, in just a few days.

Venus Express, which is due to end its mission in May 2009 | Image: ESABut wait a minute… where does all this sulfuric acid come from? After all, Venus is sometimes known as ‘Earth’s evil twin’ because of its runaway global warming, caused by excess carbon dioxide levels.

In fact, 97% of Venus’s atmosphere is made of CO2, although there are small amounts of gases such as sulfur dioxide and water vapor.

Recently discovered by the Venus Express probe is that the sulfuric acid is created when the sulfur dioxide and water vapor rise to the top of the atmosphere and are exposed to ultraviolet rays from the Sun, causing them to react and form sulfuric acid.

Why do they rise up? That’s one of the many things that remains to be found out, hopefully during this last year of the phenomenal Venus Express mission.

Click here for an interactive guide to Venus