I’ll just get right to the point.

No doubt you’ve heard the news, but if you haven’t a paper was release via NATURE about a team of astronomers who have isolated a phosphine absorption line (PH3) in their spectral analysis of Venus, using two different telescopes, several different reduction methods and measurable uncertainties. The amount of PH3 is quite small (20 parts per billion) but why it’s there at all poses the question – how?

PH3 has only recently been considered as a potential biomarker but only for rocky planets, as it can occur naturally in the gas giants, and indeed does in Jupiter and Saturn. Typically here on Earth, it’s found as a byproduct of life and is found (for example) in penguin poo.

We shouldn’t immediately conclude there are penguins on Venus of course, and to do so would be jumping the gun. PH3 can be produced by a number of natural methods, it’s just that those methods are unlikely on Venus’ hot, hostile landscape. If life is indeed the source, it may be cloud-based microbial life but even the paper itself urges scepticism here:

“… we emphasize that the detection of PH3 is not robust evidence for life, only for anomalous and unexplained chemistry. There are substantial conceptual problems for the idea of life in Venus’s clouds…”

In any case you are likely to be bombarded with news articles suggesting this possibility so bear in mind a few things. Firstly, we’ve had news stories like this before even from NASA where they’ve turned out to be false. Contaminated meteorite samples were once reported as alien bacteria, and who can forget the “arsenic based life” story which turned out to be a flawed conclusion and unrepeatable by other researchers.

It’s quite possible that despite the astronomers best efforts here, a transition from another molecule is being detected at the wrong wavelength through shift or noise in the data. Their methods appear fairly robust but it remains to be seen whether it can be repeated by other researchers or is a “double false-positive”. The absorption signature may even stem from Earth – remember the time a mysterious deep space radio signal ended up being an astronomer microwaving noodles in the next room?

The next step is trying to detect PH3 absorption from other telescopes, preferably ones in space. Only after the finding is confirmed do we then form a crack team of steampunk robots and drones to go and give Venus a closer whiff. Like all space fans though, any further exploration of Venus is welcome – life or not. Venus may tell us more about our future here on Earth.

Dylan O’Donnell 



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