Two Centuries Ago, the Sun Mysteriously Appeared Blue. Researchers Have Finally Uncovered the Reason Behind It.

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• In 1831, a massive volcanic eruption cooled the Earth’s atmosphere by 1 degree Celsius and even caused the Sun to appear in varying shades of purple, green, and even blue due to excess sulfur dioxide in the atmosphere.

• Scientists have tried for years to find the volcanic culprit, and a new study comparing polar ice shards with samples from the Zavaritskii volcano in the Kuril islands has found an exact match.

• This event is far from a historical outlier, so understanding these events could help coordinate a global response when the next catastrophic eruption hits.

“Desolate weather, it has rained again all night and all morning, it is as cold as in winter, there is already deep snow on the nearest hills.” These were the words of German composer Felix Mendelssohn as he traveled through the Alps in 1831. However, there was only one problem: it was summer.

In the spring-summer of 1831, a volcano somewhere on Earth erupted, sending massive plumes of sulfur dioxide into the atmosphere, causing a global cooling, and forcing our planet to play host to some weird climatic conditions that year.

A global cooling of one degree Celsius led to crop failures and famines around the world, but perhaps the strangest events were a variety of reports of a green, purple, and even blue-looking Sun in August. At the time, scientists have known that a volcano was the likely culprit but didn’t know which one should shoulder the blame. Now, a new study from scientists at the University of St. Andrews in the U.K. says they’ve solved the mystery: Zavaritskii volcano in the Kuril islands northwest of Japan is to blame.

The study’s lead author, University of St. Andrew’s Dr. William Hutchison, says that a break in this (unseasonably) cold case came thanks to advancements in technology that made the analysis of more volcanic evidence possible. The resul