What scientists thought caused certain classes of northern lights is not what causes certain classes of northern lights.
In a landmark study that has toppled what scientists know about the night sky, UAlberta physicists Robert Rankin and Dmytro Sydorenko found that the ionospheric feedback instability (IFI)—the mechanism thought to be the cause of certain types of northern lights—not only doesn’t cause northern lights, it may not even exist at all.