Medieval lunar observations are assisting modern academics in their investigation of a strange cluster of volcanic eruptions on Earth.
Monks and other scribes of the time wrote extensive descriptions of lunar eclipses, which occur when the moon is completely in Earth’s shadow. The incidents were supposed to presage disasters at the time.
Their texts frequently mentioned a reddish sphere surrounding the eclipsed moon, as well as more exceptional cases in which the eclipsed moon appeared to vanish totally from the sky.
“The elderly folk had never seen it like this before, with the location of the Moon’s disc not visible, as if it had vanished during the eclipse… “It was truly something to fear,” remarked Japanese poet Fujiwara no Teika of the December 2, 1229, total black eclipse.
According to Sébastien Guillet, a senior research associate at the Institute for Environmental Sciences at the University of Geneva, an especially black eclipse is connected with the presence of a high amount of volcanic dust in the atmosphere.
Guillet argues that mediaeval manuscripts hold vital information regarding a series of enormous but poorly understood volcanic events on Earth.
“Improving our understanding of these otherwise mysterious eruptions is critical to understanding whether and how past volcanism affected not only climate but also society during the Middle Ages,” Guillet said in a statement.
Guillet and his colleagues scoured 12th and 13th-century European, Middle Eastern, and East Asian sources for lunar descriptions, which, when combined with ice core and tree ring data, allow for more accurate dating of what scientists believe were some of the world’s largest volcanic eruptions.
Volcanic ash
The study, published on April 5 in the journal Nature, discovered documentation for 51 of the 64 total lunar eclipses that occurred in Europe between 1100 and 1300.
These papers also said that the moon was particularly black in six of these cases: May 1110, January 1172, December 1229, May 1258, November 1258, and November 1276.
These dates relate to five large volcanic eruptions documented from volcanic ash traces in polar ice cores: 1108, 1171, 1230, 1257, and 1276.
(Of these, only the location of the 1257 eruption is known, at the Samalas volcano on the Indonesian island of Lombok.)
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