“On the fifth night in the month of May appeared the moon shining bright in the evening, and afterward by little and little its light diminished,” an unnamed scribe wrote in the Anglo-Saxon manuscript known as the Peterborough Chronicle.
“As soon as night came, it was so completely extinguished withal, that neither light, nor orb, nor anything at all of it was seen. And so it continued nearly until day, and then appeared shining full and bright.” No, there wasn’t a cloud in the sky. We know this because the scribe went on to describe how bright and twinkling the stars appeared while the moon faded from view.
As the Peterborough writer described what was happening, not only could a high-altitude veil of volcanic aerosols blot out the moon while leaving many stars unobscured, but a series of large eruptions could have also disrupted the global climate, the researcher wrote, causing or exacerbated the cold, wet weather that made life so miserable in A.D. 1110.
A volcanic eruption in 1108
In a study published April 21 in the journal Scientific Reports, we are given a possible explanation for the moon’s disappearance on May 5, 1110, as well as the disastrous rains all that year – Volcanoes.
“The spectacular atmospheric optical phenomena associated with high-altitude volcanic aerosols have caught the attention of chroniclers since ancient times,” the study authors wrote. “Careful evaluation of ice core records points to the occurrence of several closely spaced volcanic eruptions,” which may have occurred in Europe or Asia between A.D. 1108 and A.D. 1110.
The researchers use the term “forgotten cluster” of eruptions to explain the duration of these volcanic events. They have caught the attention of ancient scribes since ancient times. Observations include “twilight glows, dimming or discoloration of the Sun, and solar coronae (Bishop’s Rings).”
“Reports of these manifestations have been used to identify the occurrence, timing, and climatic-forcing potential of large eruptions,” according to the study.
Ice cores and astronomical retro calculation
In researching the possibility of a volcanic eruption of great magnitude as a cause for the 1110 event, the team’s research found 13 narrative accounts of adverse weather, crop failure, and famine from that period, leading them to deduce that a series of volcanic eruptions had messed up Europe’s climate.
“The sources of these eruptions remain unknown,” the team wrote, “yet one eruption with a historical date in this period is that of Mount Asama in Japan.”
Further searching led to the observation that similar moon disappearances or darkest lunar eclipses have occurred after large volcanic eruptions, namely the 1600 Huaynaputina, 1641 Parker, 1815 Tambora, 1883 Krakatau, 1912 Katmai-Novarupta, 1983 El Chichón, and 1991 Pinatubo eruptions.
So what did the researchers rely on to make their observations? Ice cores from both the North and South poles, tree rings, European and Near Eastern texts spanning the early 12th century. and NASA’s Five Millennia Catalog of Lunar Eclipses.
This is what happened when Mount Asama in central Japan began erupting in late August 1108. The eruption continued until October of that year. Based on a diary written by a Japanese statesman at that time, “The eruption was described as throwing fire into the sky and rendering nearby fields unfit for cultivation, and could have plausibly contributed to the sulfate spike in the Greenland ice core and polluted the sky with enough aerosols to induce the eclipse two years later,” the team wrote.