The Moon in the Middle Ages

The Moon in the Middle Ages

When writing about the events of the the year 1178 in his Chronicle, Gervase of Canterbury interrupts his account of kings and wars to relate a very unusual occurrence in the night sky:

This year on the 18th of June, when the Moon, a slim crescent, first became visible, a marvellous phenomenon was seen by several men who were watching it. Suddenly, the upper horn of the crescent was split in two. From the mid point of the division, a flaming torch sprang up, spewing out over a considerable distance fire, hot coals and sparks. The body of the Moon which was below, writhed like a wounded snake. This happened a dozen times or more, and when the Moon returned to normal, the whole crescent took on a blackish appearance.

This account has puzzled modern astronomers – some suggest that the monks saw an asteroid crashing into the moon, while others believe that it was a meteorite that had entered the Earth’s atmosphere at just the right spot – between the monks and the moon – making the observers believe that what they saw was happening on the moon.

For the monks who saw this phenomenon this event would be very worrying indeed. For medieval people the moon was an ever-present, fascinating and mysterious object. The moon not only brought light to the night sky, but it also marked the passage of time and could determine the personality of man or woman.

Medieval Science and the Moon

By the beginning of the Middle Ages there were already many theories about the moon, which actually was considered to be a planet like Mercury, Mars, Jupiter and even the Sun. Like these other planets, the moon revolved around the Earth in a perfect circle. Medieval thinkers still had a lot of other questions to answer about the moon – What was it made of? What was the distance between it and the earth? Where did it get its light from? Why were there light and dark spots on its surface?

Christian, Muslim and Jewish astronomers all had their reasons for studying the moon and its movements – such as figuring out when religious events occurred and basing their astrological predictions. Throughout the Middle Ages one can find various astronomers at work, detailing their theories about the moon. For example, al-Hasan ibn-Haytham (965-1039) wrote two works about the moon. In this passage he explains some of the ideas that were circulating in his time about why the moon appeared the way it did:

If one were to carefully observe and consider the surface markings, one finds them to be of constant disposition, revealing no changes in themselves, neither in their form, their position and size, nor in their respective types of darkness. Superstitious men, and those who should not be taken seriously, have proposed their own, divergent opinions on the matter. Certain people hold the spots belong the lunar body itself; others believe that they exist apart from it, namely between the lunar body and the eye of the observer; still others conceive that they offer an inverted image [of the Earth], since the lunar surface is smooth and reflecting.

Ibn-Haytham disagreed with all these ideas and proposed that parts of the surface of the moon were denser than others, which made them reflect more or less light.

Someone reading medieval astronomical works will find them tedious and difficult to understand. Moreover, in most cases they were wrong. For instance, the 13th century English friar Roger Bacon understood that the moon caused the tides in oceans, but he believed this was because the rays of light from the moon “raise vapours” from the sea, which cause the waters to move. When the moon was overheard, these rays evaporated the water, which made the tide recede.

Occasionally, however, a medieval writer stumbled across some piece of knowledge that turned out to be correct. The Anglo-Saxon monk Bede was able to figure out that tides were not the same in all places of the world. In his work The Reckoning of Time, he explains:

There are those who claim and affirm that an enormous outpouring of the ocean takes place in all the streams of every region and land at one and the same time. But we who live at various places along the coastline of the British Sea know that where the tide begins to run in one place, it will start to ebb at another at the same time. Hence it appears to some that the wave, while retreating from one place, is coming back somewhere else; then leaving behind the territory where it was, it swiftly seeks again the region where it first began.

The Moon can do more than just light up the night sky

“One cannot claim to know the causes of things if one does not know the movements and dispositions of the celestial bodies, for they themselves are the causes of earthly matters” ~ Robert Anglicus (13th century)

Medieval writers believed the moon could do more than just cause tides – it could also affect ones health. Hildegard of Bingen, a famous abbess in 12th century Germany, explained that bloodletting was best done when the moon was waning (moving toward a new moon). She also found that the phase of the moon helped to determine someone’s personality. For example, if a person was conceived on the fifth day after a new moon:

if it is male, will be virtuous and loyal, courageous and steadfast. He will be physically health and live long. But if it is a female, she will be virile, quarrelsome and vindictive, but honest nevertheless. At times, though not very often, she suffers from some mild infirmity. She too can live quite long.

The phase of the moon was also important for agriculture, such as when to plant seeds. The belief was that when moon was waning it would draw water deeper into the soil, and when is waxing (becoming a full moon) the water was being drawn up and out of the soil. An agricultural treatise from 15th century Spain states that in March, “melons, cucumbers, gourds, oats, sorghum, onions and green beans can be sown in the waning moon. Cabbage seed and radishes in the old moon. Green beans and sorghum and spelt can be sown in the new moon. Graft fig trees and other trees in waxing moon.”

The Eclipse in the Middle Ages

Hundreds of accounts of solar eclipses have been preserved in medieval records. Many are often terse – just a few words – but others provide some interesting insights. For example, one German chronicle reported in 1133, “on the 4th day before the Nones of August [Aug 2], the 4th day of the week, when the Sun was declining, towards the ninth hour the Sun in a single moment became as black as pitch and day was turned into night; very many stars were seen, objects on the ground appeared as they usually do at night…”

Astronomers during the Middle Ages were just beginning to understand when an eclipse would occur, so for the vast majority of people this event was unexpected and could be scary. The historian Ibn al-Athir was eyewitness of a total eclipse in his youth in the year 1176:

In this year in the month Ramadan the sun was eclipsed totally and the earth was in darkness so that it was like a dark night and the stars appeared. That was before noon on Friday the 29th of Ramadan at Djazira Ibn Umar, when I was young and in the company of my arithmetic teacher. When I saw it, I was very much afraid; but I held on to him and my heart was strengthened. He was also learned in astronomy and told me “Now you will see that all of this will go away,” and it went quickly.”

By the later Middle Ages astronomers had become proficient at knowing when an eclipse would occur. Christopher Columbus made use of this during his fourth voyage to the New World. In 1504 he and his crew were stranded in Jamaica, and forced to rely on the local indigenous people to supply them with food. After a dispute the natives stopped bringing the food, and Columbus needed a way to convince their leader that he should continue the supplies. He had brought on the voyage a book of astronomical tables, and in it he noticed the date and the time of an upcoming lunar eclipse. Just before the eclipse occurred, he met with the native leader and told him that God was angry with them for not providing the food, and that there would be a sign of his displeasure. The lunar eclipse then occurred, turning the moon red, which frightened the natives. Within minutes they were bringing food supplies back to Columbus and his men.

The Man in the Moon

When some people look at the moon they claim they can see the face or even the whole body of a human. The idea of a man on the moon goes back to the Middle Ages, with the earliest reference coming from the English scholar Alexander Neckham (1157 – 1217). In his book De Naturis Rerum he has a small section called ‘About the mark on the moon’ where he writes:

Don’t you know that which the common crowd calls “The peasant in the moon, who carries thorns’? Therefore one says commonly: The peasant in the moon, whom a (certain) bundle weighs down / Illustrates through the thorns that stealing is never profitable.”

A few other late medieval English stories also have a similar story where the man in the moon was some peasant who gets caught stealing thorns to help him build a hedge (every villager would be responsible for helping build and maintain hedges to keep livestock from roaming into planted fields – and they would place thorns on the hedges so the animals wouldn’t be able to eat that either).

A medieval German tale explains there are two people on the moon – a man and a woman. The man has been banished there because he had placed thorns on the path to a church in order to prevent people from going to Sunday mass. Meanwhile, the woman is there because she made butter on Sunday. To add to their punishment the man carries his bundle of thorns on his back, while the woman carries a butter-tub. Another medieval legend says the man in the moon is Cain, who as punishment for the murder of his brother Abel is exiled to the moon with some twigs.

Travelling to the Moon

Stories involving people travelling to the moon are not very common in the Middle Ages – they became popular by the 17th century – but a few do exist. The Tale of the Bamboo Cutter, a tenth-century Japanese folktale, revolves around a young woman named Kaguya-hime who was sent from the moon to the earth, where she almost marries the Emperor before returning to the capital city of the moon.

In Dante’s Divine Comedy, the moon is the outermost sphere of Paradise. When the poet arrives there with his guide Beatrice, he first asks her why are there light and dark spots on the moon, to which she replies by giving a detailed scientific explanation involving optics and rays of light. Before moving on to the other planets, Beatrice reveals that this is the place in Paradise for people who were good but were forced to break their vows, such as nun who was forcibly removed from her convent.

A third tale involving travel to the moon is The Frenzy of Orlando, written by Ludovico Ariosto in 1516. This is the story of a knight named Orlando who had fallen in love with a pagan princess, but after she marries someone else he goes mad and travels around the world causing destruction. Finally, he is taken by St John the Evangelist to the moon, where he goes to the Valley of Lost Things in which Orlando finds his sanity. In her article, “Ariosto the Lunar Traveller”, Ita MacCarthy explains that the moon, which is depicted as much larger than the Earth, is a kind of allegorical junkyard:

On the moon, forgotten ancient crowns metamorphose into tumid bladders, flattery turns into stinking garlands, and human brains become liquid ooze: the world’s objects become allegorical parodies of themselves. The moon, at this point in the episode, offers something other than a mirror image of reality. It reflects back an altered version of it, one that highlights the essential rather than the outward qualities of the objects placed before it. As objects undergo a metamorphosis that reveals their essence, the moon becomes an allegory for the literary text, which also transforms reality as it reflects and reconstructs it.

Other Fun Facts about the Moon in the Middle Ages

1) The moon was believed to be cold and moist. It was said to be responsible for making the night air moister, which is why there would be dew on the grass in the early morning.

2) Roger Bacon calculated that if a person walked twenty miles a day, he would reach the moon in fourteen years, seven months and twenty-nine days.

3) In the Islamic tradition, the start of a new month does not begin until the first crescent of a new moon is sighted. This could lead to occasional problems, such as when the traveller Ibn Jubayr visited Mecca at the end of the twelfth century. He describes how the people were outside trying to spot the new crescent, which would mark the beginning of the month of Ramadan, but it was so cloudy that no one could see it. After some time someone cried out that he could see it, then others joined in, but when they approached the local judge to tell him what they saw, he ridiculed them and replied “if someone would claim to have seen the sun from behind those clouds I would not have believed him, let alone seeing a thin crescent!”

4) In Norse mythology, the moon was known as Máni and he was the brother of Sol, the Sun. They are being chased through the heavens by wolves.

5) The word Monday comes from the Old English term Mōnandæg which means ‘Moon’s Day’. In Latin, this day was called dies Lūnae, which has been transformed into modern French as lundi, in Italian as lunedì and in Spanish as lunes.

6) In a popular medieval fable, a fox lowers himself into a well with a bucket but gets trapped. A wolf comes by and the fox sees in the well, but also sees the reflection of the moon in the water. The fox convinces him that what he is seeing is a piece of cheese in the well, so the wolf uses the second bucket to go down, which lifts the fox’s bucket up, allowing him to escape. This type of story continues to be popular, such in Kitten’s First Full Moon.


“The Moon and Medicine in Chaucer’s Time,” by Laurel Braswell, Studies in the Age of Chaucer, Vol.8 (1986)

The Moon: A Brief History, by Bernd Brunner (Yale University Press, 2010)

The First Scientist: A Life of Roger Bacon, by Brian Clegg (London, 2003)

Medieval Views of the Cosmos, by E. Edson and E. Savage-Smith (Bodleian Library, 2004)

“A Note on the Man-in-the-Moon poem No.333 in Iona and Peter Opie’s The Oxford Dictionary of Nursery Rhymes (1997)”, by Thomas Honegger, Notes and Queries (March 2000)

The Medieval Natural World, by Richard Jones (Pearson, 2013)

Bede: On the Nature of Things and On Times, trans. by Calvin Kendall and Faith Wallis (Liverpool University Press)

“The Medieval Man in the Moon,” by Claudia Kren, Mediaevalia, Vol.7 (1981)

“Ariosto the Lunar Traveller,” by Ita MacCarthy, The Modern Language Review, Vol. 104, No. 1 (Jan., 2009)

“The Middle English Vox and Wolf,” by G. H. McKnight, PMLA, Vol. 23, No. 3 (1908),

The Moon and the Western Imagination, by Scott L. Montgomery (University of Arizona Press, 1999)

A Brief Introduction to Astronomy in the Middle East, by John M. Steele (London, 2008)

Solar Eclipses in Medieval Islamic Civilization: A Note on Cultural and Social Aspect“, by Hamid-Reza Giahi Yazdi, Iranian Journal for the History of Science, 6 (2008)

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