Sky Matters: is there life on Venus and if there is, what does that mean?

 The discovery of phosphine gas in the clouds of Venus could possibly indicate signs of life on the planet, scientists have said. Picture: ESO/M. Kornmesser & NASA/JPL/Caltech/PA Wire

The announcement by a team of astronomers in September that the planet Venus might harbour life may not have generated as much excitement as one would have at first imagined. As a reminder, the team found evidence of a molecule called phosphine in the Venusian atmosphere. 

Phosphine is a difficult molecule to make, and on Earth it occurs naturally only as a by-product of life. The issue is that it IS possible to make phosphine without life and the researchers noted this in the journal paper accompanying their announcement by stating: “phosphine could originate from unknown photochemistry or geochemistry”.