The discovery of a possible sign of life in Venus' clouds sparked controversy. Now, scientists say they have more proof

Four years ago, the unexpected discovery in the clouds of Venus of a gas that on Earth signifies life — phosphine — faced controversy, earning rebukes in subsequent observations that failed to match its findings. Now, the same team behind that discovery has come back with more observations, presented for the first time. The data, the researchers say, contains even stronger proof that phosphine is present in the clouds of Venus. A separate team presented evidence of another gas, ammonia. On Earth, phosphine is a foul-smelling, toxic gas, while ammonia is a gas with a pungent smell that naturally occurs in the environment. Finding these gases on Venus is unexpected. Subsequent studies challenged the results, suggesting that the phosphine was actually ordinary sulfur dioxide. But the new data has ruled out that possibility and reinforces the theory of phosphine and weak traces of ammonia in the atmosphere of Venus. Ammonia on Venus would be even more surprising and could act as a buffer to the acidity of the planet’s clouds, making it more survivable for certain known bacteria. While these findings are intriguing, cautious skepticism is warranted, and further research is needed to unravel the mysteries of Venus’ atmosphere.