An auroral flare at Jupiter

Jupiter's aurora is the most powerful in the Solar System(1). It is powered largely by energy extracted from planetary rotation(2), although there see ms also to be a contribution from the solar wind(3,4). This contrasts with Earth's aurora, which is generated through the interaction of the solar win d with the magnetosphere. The major features of Jupiter's aurora (based on far-ultraviolet(5-7), near-infrared(8,9) and visible-wavelength(10) observa tions) include a main oval that generally corotates with the planet and a r egion of patchy, diffuse emission inside the oval on Jupiter's dusk side. H ere we report the discovery of a rapidly evolving, very bright and localize d emission poleward of the northern main oval, in a region connected magnet ically to Jupiter's outer magnetosphere. The intensity of the emission incr eased by a factor of 30 within 70s, and then decreased on a similar timesca le, all captured during a single four-minute exposure. This type of flaring emission has not previously been reported for Jupiter (similar, but smalle r, transient events have been observed at Earth), and it may be related dir ectly to changes in the solar wind.