Scientists Find Root Cause of Mysterious Incident That Made the Sun Appear Blue

After 200 years, researchers finally solved the mystery of a volcanic event so bizarre, it made the sun appear blue and then cooled the planet. A remote volcano called Zavaritskii on an island of the same name that is part of Russia's archipelago in the Pacific Ocean called Simushir Island is the one blamed for it, according to PNAS. Will Hutchison, the lead author from the University of St Andrews, called it a "genuine eureka moment" when their team matched volcanic ash from Greenland's ice cores with samples from the Zavaritskii volcano, according to Smithsonian Magazine.
In 1831, a huge eruption spewed enormous amounts of sulfur gas into the atmosphere, which, through its interaction with sunlight, caused surreal hues of blue, purple, and green to scatter across the sky. The freak weather was commented upon by German composer, Felix Mendelssohn, who happened to be in the Alps when it occurred: "It is as cold as in winter, there is already deep snow on the nearest hills," according to Smithsonian Magazine. Because of the environmental impact, temperatures in the Northern Hemisphere cooled by one degree Celsius, which ushered in crop failures and famine. It released approximately 13 million metric tons of sulfur, making it one of the most important volcanic eruptions of the 19th century.
An unknown volcano erupted so explosively in 1831 that it cooled Earth’s climate. Now, nearly 200 years later, scientists have identified the “mystery volcano.”https://t.co/kNNdcSxKsz
— Private Suite Network | CJ (@PSuiteNetwork) January 4, 2025
The discovery involved huge international collaboration: Hutchison said finding the match took years of work, supported by Japanese and Russian colleagues who supplied decades-old samples from remote volcanoes. The researchers studied tiny volcanic glass shards from Greenland's ice cores—some a tenth the width of a "human hair," as per Independent. The remote setting of Simushir Island, with its former use as a Soviet submarine base, is a good explanation for no one hearing about the eruption. Though it was far away from any settlements, it was close enough to harm crops in Japan.

Hutchison said many of Earth's volcanoes are remote and not well studied. Previous theories had connected the unknown eruption to tropical volcanoes such as the Babuyan Claro in the Philippines. The new findings have brought into sharp focus how hard it will be to predict big volcanic eruptions, especially from the most remote areas of the world. Hutchison added that if a similar eruption were to happen today, this would impact global food supplies due to the reduction of sunlight, rainfall, and lower temperatures.
Science for the win! The historical records long showed a massive volcanic eruption in 1831 that brought down Earth’s avg temperature by 1°C, but they didn’t know which volcano! Now, using sulfur isotopes in Greenland ice, they traced it to Zavaritskii caldera on Simushir Island! pic.twitter.com/ruKcILCgHJ
— Ryan Katz-Rosene, PhD (@ryankatzrosene) January 6, 2025
Hutchison added that more historical records of ash fall or atmospheric anomalies from 1831 may exist, perhaps buried in some archive in Russia or Japan, according to Smithsonian Magazine. Such an eruption today would be spotted immediately with modern satellites and seismic monitors, but, Hutchison said, the lack of thorough volcanic monitoring around the world remains a serious concern in forecasting future eruptions of this size.