Six Pieces of Evidence Against the Corotation Enforcement Theory to Explain the Main Aurora at Jupiter

The most remarkable feature of the ultraviolet auroras at Jupiter is the ever-present and almost continuous curtain of bright emissions centered on each magnetic pole and called the main emissions. According to the widely accepted theory, it results from an electric current loop transferring momentum from the Jovian ionosphere to the magnetospheric plasma. However, predictions based on this theory have been recently challenged by observations from Juno and the Hubble Space Telescope. Here we review the main contradictory observations, expose their implications for the theory, and discuss promising paths forward.