Venusian phosphine: a 'wow!' signal in chemistry?

The potential detection of ppb levels phosphine (PH₃) in the clouds of Venus through millimeter-wavelength astronomical observations is extremely surprising as PH₃ is an unexpected component of an oxidized environment of Venus. A thorough analysis of potential sources suggests that no known process in the consensus model of Venus' atmosphere or geology could produce PH₃ at anywhere near the observed abundance. Therefore, if the presence of PH₃ in Venus' atmosphere is confirmed, it is highly likely to be the result of a process not previously considered plausible for Venusian conditions. The source of atmospheric PH₃ could be unknown geo- or photochemistry, which would imply that the consensus on Venus' chemistry is significantly incomplete. An even more extreme possibility is that strictly aerial microbial biosphere produces PH₃. This paper summarizes the Venusian PH₃ discovery and the scientific debate that arose since the original candidate detection one year ago. [ABSTRACT FROM AUTHOR]