Astronomers have detected a bright spot with a trailing tail in Jupiter’s aurora, caused by an electromagnetic connection to the planet’s moon, Europa. For more than a decade, the Hubble Space Telescope has returned images of the aurora at Jupiter’s poles as the emissions light up in ultraviolet wavelengths. You can watch movies of the aurora here. Scientists have long known that Io, the innermost Galilean moon, triggers a bright auroral spot, or “footprint”, in the light show. That footprint boasts a tail that streaks halfway around the planet.