On May 19, 1780, an unusual darkening of the day sky was observed over parts of New England and Canada. The darkness was so complete that candlelight was needed as early as noon in places. Researchers examining scar damage in tree growth rings believe that a large fire in Canada’s Algonquin Provincial Park contributed to the darkness, but thick fog and cloud cover likely also played a role. The episode was, and still is, interpreted by many as what kind of event? Discuss