The aurora usually occurs in the auroral oval where charged particles impact the Earth’s atmosphere. Though the aurora is relatively well studied, it still holds surprises. A new type of emission, STEVE (Strong Thermal Emission Velocity Enhancement), has been recently reported by the scientific community although it has been documented by citizen scientists for decades. STEVE appears as a glowing ribbon of bright purplish light running east-west in the night sky, with unstable picket-fence-like green emissions. It is observed in the subauroral region that is equatorward of the auroral oval, where we do not expect to see aurora. Since the first scientific report of STEVE, its nature and mechanisms have been vigorously pursued by the science community. Is STEVE a new type of aurora, or is it airglow? What mechanisms cause STEVE?
In this seminar, I will briefly talk about the discovery of STEVE, and talk about our recent efforts to understand STEVE. I will also show how we identify the magnetospheric driver of STEVE using conjugate observations from Van Allen Probes, LEO satellite, all-sky imagers on the ground, and particularly important, photographs from citizen scientists.