The detection of phosphine in the atmosphere of Venus, reported in September this year, raised a considerable excitement around the world. Not only in the scientific community, but also in the media. The discovery was strongly advertised as a possible indication of life on Venus, also mentioned in the paper published by Dr. Jane Greaves team in Nature Astronomy. As expected, astronomy specialists were highly interested in the unprecedented finding.

More recently, two independent teams checked out the results published in Nature Astronomy.

In a paper accepted for publication in the journal Astronomy & Astrophysics, a team lead by Dr. T. Encrenaz (LESIA, Observatoire de Paris, PSL Université, CNRS, Sorbonne Université), the abstract mentions that “result brings a strong constraint on the maximum PH₃ [phosphine] abundance at the cloud top and in the lower mesosphere of Venus.” In other words, Dr. T. Encrenaz team detected too low levels of phosphine in Venus to be significant for the assumption that PH₃ levels could be representative.

The second paper, the preprint of which is available at arXiv.org, the team lead by I.A.G. Snellen (Leiden Observatory, Leiden University) mentions in the abstract that “Our independent analysis shows a feature near the PH₃ frequency at a ∼2σ level, below the common threshold for statistical significance. Since the spectral data have a non-Gaussian distribution, we consider a feature at such level as statistically unreliable that cannot be linked to a false positive probability.” It is of interest to mention that the Leiden University researchers re-analyzed the data collected by Dr. Jane Greaves team at ALMA (the Atacama Large Millimeter/submillimeter Array).

In a footnote added by Snellen and collaborators article submitted for publication also to the journal Astronomy & Astrophysics, it is added that “Since the publication of GRB20, the authors alerted us about an update in the ALMA data processing script and made the new script available. In parallel, the data available in the ALMA Science Archive is undergoing (so-called QA3) reprocessing to include the same correction. The resulting reprocessed data no longer contains the strong ripples that GRB20 report and that we also find, for example as manifested in the non-Gaussian noise distribution. In these reprocessed data we do not find a clear absorption feature that can be attributed to PH3, although further exploration of these data is necessary to analyse this in more detail.”

While the discovery is of considerable interest to scientists and society, a note of caution can be added here.

Is the detection of phosphine in Venus atmosphere an extraordinary claim?

If yes, according to the late Carl Sagan, it needs extraordinary evidences to support the claim.

Although Sagan’s statement has been challenged by non-scientists, it has been statistically supported.

The final question is: has been Sagan’s assumption taken in consideration by Nature Astronomy reviewers?

Categorias:ciência, evolução, química