In 2016, watchers of the night sky above the Canadian province of Alberta observed a strange phenomenon. A purple and green ribbon snaked across the night sky, seemingly endless.
Scientists were baffled.
At first, watchers assumed that it could be some previously-unseen variation of aurora - similar to the more commonly-known aurora borealis, the “Northern Lights”. It didn’t quite fit, though. The colorful light of an aurora normally ripples horizontally across the sky, while this phenomenon instead formed a distinctive purplish or greenish vertical streak. It appeared to stretch the length of Canada, from the Atlantic Maritimes to British Columbia.