In 2008, while researching my biography of Gerbert of Aurillac, the French mathematician who became Pope Sylvester II, I visited Rome. I met my guide to the city, Costantino Sigismondi, through his website, where he had posted all of Gerbert’s known works. This year, on May 10, Sigismondi has organized a full day of lectures devoted to Pope Sylvester II at Rome’s Sapienza University. On May 12, a mass will celebrate the 1010th anniversary of Gerbert’s death. I wish I could join Sigismondi for the festivities. He's one of those rare people who brings light to the Dark Ages.
Sigismondi, an astrophysicist, teaches the history of astronomy at the University of Rome. In 2000, a friend reading Sky & Telescope chanced upon an article about “Y1K’s Science Guy,” Gerbert of Aurillac. She sent it to Sigismondi, who was astonished. Why hadn’t he known about The Scientist Pope? Sigismondi immediately contacted the Vatican and, with the pope’s support, began planning a series of lectures and events to commemorate the millennium of Gerbert’s pontificate (999-1003), including a grand requiem mass in the cathedral of Saint John Lateran in 2003.
Now we were in the square on the north side of the basilica; we turned to see an obelisk covered with hieroglyphics. “That wasn’t there when Gerbert was pope. We need to go to the Campo Marzio, close to the Pantheon. Ten years before Christ, Augustus put an obelisk there to make a sundial. One of the legends of Gerbert, you remember—William of Malmesbury tells it—is the story of Gerbert and a servant walking through the Campo Marzio, and Gerbert suddenly understands the Augustine obelisk. This is the story of the buried treasure.”
If this story were set in Reims, I could pooh-pooh it as utter fantasy. But Rome? In 2005, archaeologists were using a coring drill to survey the foundations of Caesar Augustus’s palace on the Palatine Hill. Fifty feet down, the drill plunged into a void. Sending down a camera, the crew discovered a sacred grotto—a round, domed room about twenty-five feet high and twenty-five feet across, covered with mosaics of marble and seashell. In the soft light of the remote-sensing probe, they glittered like gold.
“The meridian occurs in this line,” Sigismondi said, putting a blank sheet of white paper near the line so that the faint sun on this cloudy day was more visible. “It’s different for every day. It goes to 12:24 in February, comes back to 12:20 now in March. And back to 12 in October. This is the so-called equation of time. If you take this and put it to local noon time, noon”—when the image of the sun crosses the line—“equals halfway between dawn and sunset.
“I am practically the resident astronomer of Santa Maria degli Angeli,” he said. He has held conferences and astronomy classes in the church; on a side table, surrounded by sacred literature for sale, is a one-euro pamphlet he wrote called “Astronomy in the Church.” The pamphlet gives his email address if anyone would like further information on this partnership between religion and science.
Sigismondi has also used the sundial for original scientific research. “I measure this meridian line with video cameras to take scientific information as accurate as possible. Looking at the sun, it is possible to measure all the parameters of the solar orbit with a precision difficult to achieve with a normal telescope. You can measure the angles of the sun with greater precision because there is no lens—there is no border effect. The border effect of a lens is remarkable. The pinhole, on the other hand, is aberrationless. The only abberation is due to the atmosphere.
“What’s the link between this meridian line and our Gerbert? There’s no real link, because this line was built seven centuries later.
“And this was possible in Gerbert’s time. If you use only the duration of the seasons, then Ptolemy works. If you can see the image of the sun—as you can with this sundial—then Ptolemy fails.”
Sigismondi speculates that this kind of sundial was the sensational object that Gerbert made for Otto III in Magdeburg—what Thietmar of Merseburg called an horologium, a “time-keeper,” translated variously as an astrolabe, a nocturlabe, a clepsydra, a celestial sphere, or a sundial. “This kind of clock is very easily made by someone like Gerbert,” Sigismondi said, “someone brilliant who understood the idea of using a tube to observe the stars, someone who could make his spheres. A sighting tube is not so different from the type of camera obscura you have here. The function of the church is just to make a dark space so that the light coming through the pinhole can be seen.
“We can’t say that this is what Gerbert made at Magdeburg, but there is room to dream in the history of science. We can’t say he didn’t. And it’s something he could have done. It’s plausible. Gerbert was about four hundred years ahead of the contemporary people, scientists and scholars included. Many of them understood that he was really outstanding. He was very respected as pope. I would like to see him sainted, or at least blessed. Abbo was sainted, and Gerbert was better than Abbo.”
The more time I spent with him, the more he seemed like Gerbert himself—Equally in leisure and in work we both teach what we know, and learn what we do not know. Or, perhaps like Gerbert’s beloved friend, the sweet solace of his labor, a man with the same first name: Costantino Sigismondi was Gerbert’s twenty-first century Constantine, who would keep the story of The Scientist Pope alive.
Join me again next Wednesday at nancymariebrown.blogspot.com for another writing adventure in Iceland or the medieval world.