Dark Days
Collier's New Encyclopedia (1921)
or days on which the light of the sun appears to be unnaturally shrouded or discolored, have been recorded throughout human history and were formerly regarded as ominous of evil. Eclipses were doubtless the cause of many of the dark days mentioned in the older annals, as, for for instance, the fadays mous "Black Day" of 1715 in London. But what are now better known as dark days are commonly the result of accumulations of dust or smoke in the atmosphere, sometimes originating in distant parts of the globe. The dust from the famous eruption of Krakatoa, for instance, not only completely hid the sun in that portion of the world during the period of the eruption, but it is known to have spread gradually through the whole earth's atmosphere, being the cause of peculiar meteorological phenomena for many months afterward. In the United States, forest fires are the principal cause of dark days. The great Idaho fire of 1910 resulted in the occurrence of such days over a considerable belt of the country, while haze was reported by ships on the Pacific Ocean at a distance of 500 miles west of San Francisco. The historic New England dark day of 1780, when the people flocked to church in the belief that the end of the world was at hand, was caused by great forest fires along Lake Champlain, and the more recent "Yellow Day" in the same section (Sept. 6, 1881) was probably due to the burning of extensive peat bogs in Labrador.
What Has Changed in the Last Century
Collier's had the physics right in 1921: dark days are mostly smoke and dust, not omens. What has shifted is the detail. Tree-ring fire scars studied in the 2000s point to fires in the Algonquin Highlands of Ontario, rather than Collier's Lake Champlain, as the source of the smoke that darkened New England on 19 May 1780. The phenomenon itself has kept recurring on a continental scale — the 1950 Chinchaga fire in Alberta threw a smoke pall that dimmed the sun across eastern North America and turned the moon blue in Britain, and smoke from Canadian and western US wildfires has repeatedly turned skies orange over cities in recent years. Volcanic dark days also continue to be studied as Collier's described them, with Pinatubo's 1991 eruption measurably cooling the globe for about two years.
Written for this edition, 2026.