There has been a lot of media coverage in scientific circles this week regarding a recent discovery on the atmosphere of Venus, and which may indicate some form of life on our neighbouring planet. At the very least, it is causing astronomers who study planetary atmospheres to rethink some of their existing models.

The actual result seems rather mundane at first glance. Terrestrial telescopes located in different parts of the world were used to measure the absorption spectrum of electromagnetic radiation in the atmosphere of Venus. By comparing the spectrum with measurements that had been made on Earth, the astronomers working on this project determined that the atmosphere of Venus contains a significant amount of a chemical known as phosphine (denoted by chemists as PH3).

So why should we be interested in phosphine on an alien world? There are thousands of chemicals in every planetary atmosphere, and this is just a small component of the Venusian atmosphere. It shouldn't be significant to anyone except a few specialists studying the planet Venus.

But phosphine has one unique property that makes the discovery quite interesting. On Earth, the vast majority of phosphine in the atmosphere is producing by the decay of plant life. It is a form a marsh gas created when organic materials decays.

So does that mean that the surface of Venus contains swamps and bogs, filled with alien plants that are rotting away?

We just don't know. Phosphine can be produced by reacting phosphorous with metallic compounds and acids, but on Earth this reaction is not common in nature. It is primarily an industrial process used in manufacturing microchips and in fumigating clothing. In the natural world, phosphine is almost always an indication of decaying organic matter.

It is interesting to note as well that previous probes sent to the gas giants, Saturn and Jupiter, have also detected atmospheric phosphine. However the reactions in the atmospheres of those planets can generate phosphine, and their relative distance from the Sun means that any small amount generated will remain for a long time.

But Venus is different. The chemicals and reactions in its atmosphere are not the type that produce phosphine in the gas giants. And perhaps of great importance is that Venus is closer to the Sun and as such receives a significant flux of ultraviolet radiation which quickly destroys the phosphine molecules. So not only does Venus contain phosphine, but something on that planet is generating it so quickly that it can replenish the molecules destroyed by solar radiation.

Scientists have so far been unable to explain the presence and production of phosphine on Venus. No known process exists that can generate phosphine on Venus, without changing our understanding of that world. The obvious answer, although strange to think about, is that Venus has some form of plant life on it.

Of course it is far too early to declare that we have found life on another planet. We know very little about the surface or the atmosphere of the planet Venus, and there are many reactions that could be generating this unexpected supply of phosphine. 

But it is an interesting discovery none the less, and just might be the first signs of alien life. Only time and more experiments will tell.