An international team of astronomers detected phosphine (PH3) in the atmosphere of Venus. They studied the origin of phosphine, but no inorganic processes, including supply from volcanos and atmospheric photochemistry can explain the detected amount of phosphine. The phosphine is believed to originate from unknown photochemistry or geochemistry, but the team does not completely reject the possibility of biological origin. This discovery is crucial to examine the validity of phosphine as a biomarker.
These observation results were presented in J. S. Greaves et al. “Phosphine Gas in the Cloud Decks of Venus” in Nature Astronomy published on September 14, 2020.