Origins of Phosphine on Venus

In 2020, the unexpected detection of phosphine-a potential biosignature-high in Venus's atmosphere stunned the scientific community, since the harsh environment of the planet seemed utterly incompatible with life as we know it. Phosphine is produced by microbes on Earth and breaks down quickly in oxidizing atmospheres, yet astronomer Jane Greaves's team found it at puzzlingly high concentrations in the temperate cloud layer 50 kilometers above Venus's hellish surface. The findings, initially detected using powerful radio telescopes, were disputed by other astronomers who argued the signal was likely sulfur dioxide contamination, but further analysis and a 2024 redetection supported the original claim.

Attempts to explain the phosphine through non-biological means-ranging from lightning and volcanic activity to meteoritic delivery-have largely fallen short, with models failing to reproduce the observed concentrations under any plausible Venusian conditions. Critics argue that incomplete knowledge of Venus's geology leaves room for alternate interpretations, particularly ongoing volcanic activity. While some suggest microbial life in the clouds as a possible source, others propose that the gas may be pointing to previously unknown geologic or photochemical processes.

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