New England's Dark Day

Well, what can I say about New England's dark day? Maybe the first thing to notice is that it's an unknown day for many (including me, until some hours ago). It all happened in May 19, 1780. A strange darkening of the sky occured that day; the sky was allegedly so dark that it was necessary to light candles from noon to midnight, and this phenomenon was experienced in the New England area and some parts of Canada.
The most amazing part of this story is that it's still a mystery what happened that day, as there are no certain conclusions about what caused the darkening. The most common theory is that a heavy fog and smoke originated from nearby forests in fire provoked a darkening of the sky that lasted for many hours. Supposedly, right after midnight, the darkness just vanished and the stars were visible again. Weird, isn't it?