DAVID GREENE, HOST:

Good morning. I'm David Greene. Scientists in Canada have been wondering about STEVE for a long time - no, not our Steve. This STEVE is short for Strong Thermal Emission Velocity Enhancement. It's this purple ribbon of light you can see streak across the night sky in parts of Canada. Some assumed it was an aurora, but the CBC reports that that is not the case. Scientists are still figuring out where the energy that causes STEVE's light comes from. Solving the mystery of STEVE on MORNING EDITION. Transcript provided by NPR, Copyright NPR.