Is there life on Venus? We once envisaged an alien world hidden beneath its yellow clouds. Through advances in astronomy, we now know that Venus is rather uninhabitable. It's scorching hot with a toxic sulfur dioxide clouds. The air pressure on the surface is literally crushing.
A study in September 2020 noticed an anomaly in the atmosphere of Venus. By pointing a telescope at the planet, researchers detected much more phosphine gas than expected in its atmosphere. This report set of a flurry of publicity and excitement, because the only way we know of to make this much gas involves microbial processes. The scientists were very careful in writing about their findings, conscious of the fact that extraordinary claims require extraordinary evidence, but it was widely hypothesized that either this was a newly discovered reaction in the atmosphere or a sign of microbes on Venus.
But in November of 2020, the authors contacted the journal to say that they found mistakes in the way that they processed some of their telescope data. They are in the process of correcting their article. In the meantime, other groups also delved into these findings. In January 2021, another group of researchers published their analysis, and they concluded that the gas was likely sulfur dioxide, not phosphine, high up in Venus's atmosphere.
So, scientists didn't find signs of alien life on Venus after all. Nonetheless, they managed to improve their techniques and calibrations for observing faraway planets. And — importantly — the scientific process of discovery, debate, and correction when necessary worked exactly as it should have.