For distant exoplanets, scientists usually cannot observe a solid surface directly, forcing them to rely on changes detected in atmospheric signals. “People tend to overlook planetary rotation, but it is absolutely key to understanding a planet’s climate,” said Stephen Kane, a planetary astrophysicist at the University of California, Riverside. This problem is clearly illustrated by Venus, where atmospheric circulation moves dramatically faster than the planet’s surface. The finding means future observations of exoplanets must carefully account for atmospheric dynamics before scientists draw conclusions about planetary rotation. Scientists could compare planets with different rotation rates and investigate whether slow spinning appears repeatedly among planets that develop extreme greenhouse climates.