Sand and Stars

Hypatia, Mathematician and Astronomer

From Euphrosyne Doxiadis (1995): The Mysterious Fayum Portraits: Faces from Ancient Egypt, Portrait of a woman, probably from er-Rubayat, c. 160-170 AD British Museum, London, An idea of how Hypatia might have looked.
From Euphrosyne Doxiadis (1995): The Mysterious Fayum Portraits: Faces from Ancient Egypt. A portrait of a woman, probably from er-Rubayat, c. 160-170 AD British Museum, London, An idea of how Hypatia might have looked.

19 Apr 2016

On the northwest shore of the Moon’s lovely little Sinus Asperitatis (Bay of Asperity) lies a crater that commemorates Hypatia, one of the last great thinkers of ancient Alexandria, and one of the first women to study and teach mathematics, astronomy and philosophy.

Crater Hypatia has been battered beyond recognition by subsequent impacts. Yet I think this beautiful wrecked formation on the face of the Moon is a fitting memorial to Hypatia who, in 415 AD, was torn to pieces by a mob of fanatical Christians agitated by Bishop Cyril and led by Cyril’s right-hand man, Peter the Lector.

In the aftermath of her murder, the Alexandrian Platonic school was sacked and burned on orders from Cyril, pagan temples were torn down, and there was a mass exodus of intellectuals and artists from the city of Alexandria. All Hypatia’s work was lost except for its titles and some references to it. As Carl Sagan put it in his book, Cosmos: “Her remains were burned, her works obliterated, her name forgotten. Cyril was made a saint.”

Very little is known about Hypatia; there isn’t much in the way of primary sources (although there is a lot of speculation and fiction). We don’t even know what she looked like (albeit there are some beautifully romanticised paintings portraying her). Only a few fragments of work have come down the ages to us, and almost none can be attributed to Hypatia, except a couple of technical works on mathematics and astronomy.

Fortunately, one of Hypatia’s devoted pupils, Synesius of Cyrene, left seven letters (one a fragment) addressed to her, as well as letters in which he mentioned her. From his letters we get a picture of Hypatia as a beloved and revered teacher; he overflows with admiration and reverence for Hypatia’s knowledge and scientific achievements. In one letter he asks for her advice on the design of a hydrometer, and in a letter to Paeonius, he describes the features of the astrolabe he and Hypatia constructed and that he has enclosed with the letter. And in a letter to his close friend and fellow student, Herculian, he wrote of Hypatia, “You and I, we ourselves both saw and heard the true and real teacher of the mysteries of philosophy.”

Raphael’s magnificent ‘School of Athens’ (c1509-1510). Hypatia appears in the lower left, wearing a white robe.

Born in Alexandria, the exact year of Hypatia’s birth is disputed. Scholars long held that she was born in 370 AD but modern historians believe 350 AD to be more likely. She was the daughter of Theon, a philosopher and mathematician at the Museum. The identity of her mother is a complete mystery. Theon closely supervised every aspect of his daughter’s education. According to legend, he was determined that she develop into a ‘perfect human being’ – this in an age when women were often considered to be lesser humans!

Around 400 AD she became the head of the Platonic school in Alexandria, an achievement that in itself is nothing short of astonishing. Hypatia and her father wrote an 11-part commentary on the Almagest, the celebrated astronomy book by Ptolemy, the most influential Greek astronomer of his time.

She edited Apollonius’ Conics, which divided cones into different parts by a plane. This concept developed ideas of hyperbolas, parabolas, and ellipses. With her work on this important book, Hypatia made the concepts easier to understand, thus ensuring the work’s survival through many centuries. She wrote a commentary on Diophantus’s 13-volume Arithmetica. She constructed astrolabes and hydrometers, but did not invent either of these, both of which were in use long before her birth.

There is no doubt that Hypatia gave Alexandrian neoplatonic philosophy its most brilliant hour. But it was not a propitious era in which to be a philosopher or a scientist. The Roman Empire was converting to Christianity and more often than not the Christian zealot saw only heresy and evil in philosophy, mathematics and science. 

This is just how I imagine the Great Library at Alexandria
This artistic rendition is just how I imagine the Great Library at Alexandria

In 412 AD Cyril, a fanatical Christian, became Bishop of Alexandria. His hostilities toward other faiths bordered on rabid. He needed a triumph over paganism. In Hypatia, he found it.

Further, he was involved in bitter hostilities with Orestes, the Roman Prefect of Egypt, a former student and long-time friend of Hypatia, as church and state fought for control of Alexandria.

While the precise details of Hypatia’s murder remain unknown, both Socrates Scholasticus and John of Nikiu tell the same horrific story of her murder at the hands of the mob of Christians and, in the aftermath of her murder, the rampage of destruction of anything to do with science and learning. (Although no-one knows with certainty how large and how diverse the collection was, it is estimated to have contained as many as 700,000 scrolls. What an incalculable loss to mankind.)

The last pagan scientist in the western world, Hypatia’s violent death coincided with the last years of the Roman Empire. Her death ended seven centuries of philosophy in Alexandria. And since there were to be no significant advances in mathematics, astronomy or physics anywhere in the West for another 1,000 years, Hypatia has come to symbolise the end of ancient science. Though the decline had already been in progress for several centuries, after Hypatia came only the chaos and barbarism of the Dark Ages.


What a lot her beautiful and battered crater on the Moon symbolises.

Crater Hypatia

Image credit Lunar Orbitor 4

What a delight to see the crater named for this remarkable mathematician, astronomer and philosopher. According to my favourite lunar book – the 1955 The Moon by H. Percy Wilkins and Patrick Moore – Hypatia is…

“A remarkable formation, distinctly triangular and 30 miles in diameter. The walls rise 7,000 feet on the east, while there is a deep crater, A, on the south-east wall. On the west there are gaps in the wall, which is also low on the north. On the floor is some faint detail, including a hill. To the north-west is a great rocky mass, and on the north-east a mass of craters of which F and K are the deepest. To the west are isolated hills running north and south. On the north is a ring, F, containing a central crater.” 

It’s a very odd-looking crater. It been battered by small impacts that have eroded, notched and chipped away at its rim, leaving a very irregular and uneven rim. It also is an odd and interesting shape; it appears as if an oblique impactor came flying in low from the north-west. And it seems fitting that the crater named for such a scholar and teacher is surrounded by ten satellite craters.

A beautiful ghost carter lies south-east of her battered crater. Ghost craters really are ghostly they way they display such enigmatic and enticing hints of the crater that once was before it was filled to its rim with lava. And Hypatia M is a quintessential ghost crater – an ethereal outline buried in the lava, much as Hypatia is buried in history with but an ethereal outline to tantalise us. Lovely!


Hypatia’s sunrise ray

I have never seen it, but Crater Hypatia has a double sunrise ray. Elusive, beautiful and short-lived, there is little as lovely to see as when the rising sun projects a beautiful ray of light through a cleft in a crater wall or and mountain.

By all accounts, Hypatia’s sunrise rays are simply stunning as one ray spills through a gap in her eastern wall creating a shining ray on her crater floor which is still inky dark, while a cleft in her western wall creates a second ray that streams out across the terrain west of the crater.

One night I’ll get to see Hypatia’s shining rays of light.

Rimae Hypatia

Consolidated Lunar Atlas Plate E9, showing the two Roman-numeraled rilles in the System of Lunar Craters.

Rimae Hypatia is a very broad 180 kilometre rille that lies about 70 kilometers north of the crater, on the border between Mare Tranquilitatis and Sinus Asperitatis. Hypatia I has two distinct parts. Showing amazing detail, my telescope and I ambled down the broad rilles starting from the western end. After stumbling into the crater pit Moltke AC that lies directly on top of the most easterly rille, I continued on down U.S. Highway 1… which was what the Apollo 10 and Apollo 11 crews called the part of the rilles close to the crater Moltke. What a lovely amble along a lovely rille. 


Copyright © Susan Young 2016