New results from the ultraviolet spectrograph instrument on NASA’s Juno mission show the birth of storms at Jupiter’s poles for the first time. The research results are published in the journal AGU Advances.
Morning storms were first detected by the Hubble Faint Object Camera in 1994. They consist of a brief but intense increase in brightness and expansion of Jupiter’s main auroral oval – an elongated curtain of light that surrounds both poles – near where the atmosphere emerges from darkness into the early morning region. Before Juno, observations of Jupiter’s ultraviolet radiance offered only side views, obscuring everything that happens on the planet’s night side.
“Observing Jupiter’s aurora from Earth prevents you from looking beyond the limb, to the night side of Jupiter’s poles. Other spacecraft – Voyager, Galileo, Cassini – were explored from relatively great distances and did not fly over the poles, so they might not see the full picture, ”explains Bertrand Bonfond, researcher at the University of Liège in Belgium and host author of the study. “This is why Juno’s data is truly a game changer, allowing us to better understand what’s happening on the night side, where the storms break out.”
As a result of the study, scientists have found that dawn storms are born on the night side of the gas giant. As the planet rotates, the approaching dawn storm moves with it towards the daytime. There, these complex and very bright auroras grow even brighter, emitting hundreds to thousands of gigawatts of ultraviolet light into space. The jump in brightness means morning storms are throwing at least 10 times more energy into Jupiter’s upper atmosphere than typical auroras.