by REBECCA PAVELEY
14 APRIL 2023
A diagram from De sphaera mundi (c.1230), an introduction to astronomy by Johannes de Sacrobosco (c.1195-c.1256)
EVIDENCE gathered from medieval monks about lunar eclipses has shone new light on the understanding of volcanic eruptions during the period. Some believe that these led to the onset of the “Little Ice Age”, when a warm period for the world’s climate was followed by prolonged cooling.
Scientists used historical sources, including observations, recorded in monasteries, of lunar eclipses, and chronicles kept by courtiers in the East, to seek evidence of volcanic eruptions. Volcanic dust in the atmosphere can lead to solar dimming, coronae, or “bishop’s rings” — when a halo is observed around the sun — and dark total eclipses.
Monks studied eclipses because a blood-red-eclipsed moon was seen as a possible sign of the apocalypse, and accurate lunar observations were crucial to identifying the Easter full moon, thereby setting the date for Easter Day and moveable feasts in the liturgical calendar.
One of the tests studied from the monastery of Santo Domingo de Silos, in Spain, between 1090 and 1109, records that “the Sun was obscured and the Moon turned into blood.”
Evidence gathered from these sources suggests that, between 1100 and 1300, 64 eclipses were observed from Europe, 59 from the Middle East, and 64 over East Asia. Of the 64 lunar eclipses in Europe during that period, monks described 51, noting that five were especially dark — something that can occur when dust from volcanic eruptions is present in the stratosphere.
The research drew in scientists and researchers from different disciplines and from around the world, including the Universities of Saskatchewan, Cambridge, Dublin, Washington, and Bern, and three in France. Their report has been published in the journal Nature.
“This work is a really novel example of interdisciplinary research, bringing together threads of evidence from medieval history, paleoclimatology, and atmospheric physics,” said Dr Matthew Toohey, an assistant professor in the Department of Physics and Engineering Physics in the USask College of Arts and Science, and a co-author of the paper.
“Volcanic eruptions are really important for understanding past climate variability —eclipse observations can be used to help determine the timing of past eruptions, many of which are otherwise only known of because of the chemical markers in polar ice cores.”
When volcanoes erupt, spewing ash and sulphur into the atmosphere, the resulting haze can decrease the intensity of sunlight that reaches the surface, which cools global temperatures over a period of years.
The research will also be used to understand future climatic changes.
EVIDENCE gathered from medieval monks about lunar eclipses has shone new light on the understanding of volcanic eruptions during the period. Some believe that these led to the onset of the “Little Ice Age”, when a warm period for the world’s climate was followed by prolonged cooling.
Scientists used historical sources, including observations, recorded in monasteries, of lunar eclipses, and chronicles kept by courtiers in the East, to seek evidence of volcanic eruptions. Volcanic dust in the atmosphere can lead to solar dimming, coronae, or “bishop’s rings” — when a halo is observed around the sun — and dark total eclipses.
Monks studied eclipses because a blood-red-eclipsed moon was seen as a possible sign of the apocalypse, and accurate lunar observations were crucial to identifying the Easter full moon, thereby setting the date for Easter Day and moveable feasts in the liturgical calendar.
One of the tests studied from the monastery of Santo Domingo de Silos, in Spain, between 1090 and 1109, records that “the Sun was obscured and the Moon turned into blood.”
Evidence gathered from these sources suggests that, between 1100 and 1300, 64 eclipses were observed from Europe, 59 from the Middle East, and 64 over East Asia. Of the 64 lunar eclipses in Europe during that period, monks described 51, noting that five were especially dark — something that can occur when dust from volcanic eruptions is present in the stratosphere.
The research drew in scientists and researchers from different disciplines and from around the world, including the Universities of Saskatchewan, Cambridge, Dublin, Washington, and Bern, and three in France. Their report has been published in the journal Nature.
“This work is a really novel example of interdisciplinary research, bringing together threads of evidence from medieval history, paleoclimatology, and atmospheric physics,” said Dr Matthew Toohey, an assistant professor in the Department of Physics and Engineering Physics in the USask College of Arts and Science, and a co-author of the paper.
“Volcanic eruptions are really important for understanding past climate variability —eclipse observations can be used to help determine the timing of past eruptions, many of which are otherwise only known of because of the chemical markers in polar ice cores.”
When volcanoes erupt, spewing ash and sulphur into the atmosphere, the resulting haze can decrease the intensity of sunlight that reaches the surface, which cools global temperatures over a period of years.
The research will also be used to understand future climatic changes.
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