The year 1110 CE is noteworthy for a few big events – battles of the Crusades were being fought everywhere, King Henry V of Germany married the 8-year-old Matilda, daughter of King Henry I of England, who was busy adding a chapel to Windsor Castle. Oh, and the Moon disappeared completely. Wait … what?
“On the fifth night in the month of May appeared the Moon shining bright in the evening, and afterwards by little and little its light diminished, so that, as soon as night came, it was so completely extinguished withal, that neither light, nor orb, nor anything at all of it was seen.”
That eyewitness account reported in the Peterborough Chronicle — one of four Anglo-Saxon Chronicles, which are records of the history of England after the Norman Conquest – might today be dismissed as a lunar eclipse … except no lunar eclipse extinguishes the light of the Moon so completely that no faint shadow or corona can be seen. A new report in the journal Scientific Reports may finally settle nearly 1,000 years of arguments about the mysterious lunar disappearance.
“Here we show that a unique medieval observation of a “dark” total lunar eclipse attests to a dust veil over Europe in May 1110 CE, corroborating the revised ice-core chronologies.”
One of the most accurate ways of determining what happened in a given ancient year or time period it to study ice cores from long-frozen, glacier-covered lands like Greenland and Antarctica. The ‘disappearing moon of 1110’ is well-known and researchers figured they had it solved when an ice core from Greenland showed a layer containing evidence of an eruption in 1004 by Iceland’s Hekla volcano, known as the ‘Gateway to Hell’ for its frequent violent eruptions. Huge deposits of sulfur in the 1110 zone and years after it indicated a heavy layer of volcanic dust floating around the world, causing climatic change and non-sun-related lunar eclipses. Case closed on the 1110 ‘really total’ lunar eclipse … right?
“A few years ago, one study concluded that a timescale called the Greenland Ice Core Chronology 2005 (GICC05) was off by up to seven years in the first millennium CE, and by up to four years early in the next millennium.”
Oops. That miscalculation pushed the Hekla eruption back to 1104, meaning its clouds would have been gone by 1110. The prompted co-author and palaeoclimatologist Sébastien Guillet from the University of Geneva in Switzerland and his team to look at an ice core from Antarctica for a more accurate reading. That core sample showed evidence of a significant atmospheric event beginning in 1108 and continuing into 1110 and beyond. They then went back to historical records to see what other volcanoes might have erupted around then. That’s when they found a Japanese reference to an event in 1108.
“The sources of these eruptions remain unknown, but we propose that Mt. Asama, whose largest Holocene eruption occurred in August 1108 CE and is credibly documented by a contemporary Japanese observer, is a plausible contributor to the elevated sulfate in Greenland.”
Mount Asama is the most active on Honshū, the main island of Japan. In May 1783, Mount Asama began a three-month eruption that killed at least 1,400 people and a plume that was responsible for the was responsible for the five-year “Great Tenmei Famine” that killed at least 20,000 more. While the records are not as detailed, they indicate that the eruption of Mount Asama in 1108 was twice as large.
Guillet’s research found “severe climatic anomalies” across Western Europe between 1109 and 1111 CE. This time, the ice core was accurate – it matched similar layers of sulfur in tree rings from the same period. NASA records indicate seven total lunar eclipses would have been observable in Europe between 1100 and 1120 CE. And astronomers note that clouds and haze caused by volcanoes can affect the brightness of lunar eclipses. Now we know that they extinguished one in 1110 like a candle in the wind.
You can’t hide from the core.