Medieval records of monks and chroniclers have dated the planet’s greatest eruptions to hundreds of years ago. This was helped by observations of abnormally dark lunar eclipses, in which dust from volcanoes does not allow the Sun’s rays to pass through the Earth’s atmosphere, according to the study. published in the journal Nature.
A total lunar eclipse occurs when the moon is completely immersed in Earth’s shadow. Usually, at these times, the Moon remains visible and acquires a reddish hue due to light rays scattered through the Earth’s atmosphere and reaching the Moon’s surface. However, after large volcanic eruptions there can be so much dust in the atmosphere that rays cannot pass through it, and during eclipses the Moon is almost invisible.
Scientists from the University of Geneva decided to examine many medieval texts describing lunar eclipses in order to date little-known volcanic eruptions more precisely. It took scientists five years to study hundreds of annals and chronicles dating from the 12th-13th centuries, and written mainly by monks from Europe and the Middle East. “In addition, we used observations from Ukrainian and Russian chronicles,” the study says.
Medieval chroniclers meticulously described various historical events, such as rulers’ actions, important battles, natural phenomena, and mass starvations. Of the 64 total lunar eclipses observed between 1100 and 1300 AD, chroniclers carefully described 51. And in five of them they noted that the Moon was unusually dark at the time of the eclipse.
Knowing that volcanic eruptions can pollute the atmosphere with ash throughout the year, scientists have been able to associate individual lunar eclipses with major eruptions. “Because we know the exact dates of the eclipses, this allows us to use the observations to specify the period of time when the eruption should have occurred”, explained Sébastien Guillet, co-author of the work.
In comparing “dark” lunar eclipses with powerful volcanic eruptions, data from ice cores taken from Antarctica and results from a study of tree rings also helped. “By comparing data from ice cores and descriptions of eclipses from medieval texts, we were able to more accurately estimate when and where the largest eruptions occurred during this period,” explained co-author Clive Oppenheimer of the University of Cambridge.
According to scientists, the period 1100 – 1300 AD is known as the era of frequent and strong volcanic eruptions on Earth. One of 15 eruptions that took place in the mid-13th century, according to a new study, was found to be comparable in strength to the famous eruption of the Tambora volcano in 1815, which led to a “volcanic winter” a year later. “. , when the rivers and there was severe hunger.
