In 2020, a team of researchers found something surprising in the high clouds of Venus. Earth-based telescopes detected the spectral signature of phosphine, a simple molecule that should have no business persisting in those extremely acidic clouds. Cautiously excited, the researchers wrote that the phosphine could be the result of “unknown photochemistry or geochemistry”—or, they noted almost coyly, “possibly life.” It was a thrilling possibility. “Signs of Life Found in the Clouds Surrounding Venus,” one headline blared; another, “Aliens Were on Venus This Whole Time?!” It was also, it turned out, a false alarm. The phosphine not only wasn’t a signal of life, but probably wasn’t even there at all, a swing-and-a-miss of data interpretation. The clouds of Venus were still, as far as anyone knew, as uninhabited as they’d always seemed. Scientists took the false alarm in stride. Back to the drawing board, they seemed to say, shrugging—or back to their telescopes at least. This is how science works, after all: gradually, in small steps, in announcements and skepticism and reconsideration of the data. …