Life on Venus? All the times we thought we found aliens

After the news from Venus we take stock of the many times we have deluded ourselves that we have found extraterrestrial life, intelligent or not

In 1996 this image of an alleged Martian fossil bacterium went around the world (photo: Encyclopaedia Britannica) In the atmosphere of the planet Venus there is a compound called phosphine. Of this the authors of a research published in Nature Astronomy are sure, or almost. The reason for the caution is that distinguishing a compound in concentrations of the order of parts per billion with radio telescope is a delicate matter. Even if the authors are convinced of the signal, they know what discovery needs to be confirmed.

If it is phosphine, where does it come from? This, you know, is the reason why all the newspapers in the world have talked about research: could it have been produced by microbes? The authors have elaborated on this hypothesis in other works, but again recommend caution. The biological hypothesis is taken into consideration by analogy: on Earth we know that some bacteria produce this gas. Phosphine can also be produced non-biologically, but for what we now know of Venus chemistry it shouldn't happen.

Planetologist Carl Sagan, who had speculated on the possibility of microbial life on Venus, repeated that for Extraordinary claims need extraordinary proof. At the moment there aren't, as the authors themselves acknowledge. The discovery is exciting, because up to now the protagonist of astrobiology in the solar system had been Mars, but we must accept that that phosphine could be produced without the intervention of life.