How ancient people studied and predicted solar eclipses

Dragon bones, mysterious drawings and simple mathematics reveal ancient eclipses

During an eclipse, as the moon begins to slowly cover the sun, crescent-shaped shadows appear on the earth and the world plunges into an eerie daylight twilight. This will happen across much of North America on Monday.

How did ancient cultures react to the darkness hiding the light? Over the past few decades, a scientific field called archaeoastronomy has emerged to study such questions. And while it's difficult to know what the early people who stood in the eclipse's shadow imagined – and increasingly difficult the further we go into the past – archaeoastronomers are using clues ranging from birch bark books to petroglyphs to the bones of ancient Chinese oracles to piece together these bygone eras. stories about space.

Rhythm in 6/5

People have calculated the frequency of solar eclipses for thousands of years. Many ancient cultures predicted these events mathematically, using what Anthony Aveni, a pioneer of archaeoastronomy and professor emeritus at Colgate University, calls the “6/5 rhythm.” Solar and lunar eclipses typically recur every six lunar months or, less commonly, every five lunar months. Over time, by observing and calculating these intervals, the ancient Mayans, Chinese, and Babylonians developed two predictable patterns when the same solar and lunar eclipses recurred: one pattern spanned 41 months, the other 47. Here's what these patterns look like, labeled “A” and “B”:

A. The 41-month pattern: 6 + 6 + 6 + 6 + 6 + 6 + 6 + 5 = 41 months, or about 3.4 years, after a total or near-total eclipse, an almost identical eclipse occurs.

Or:

B. 47 month pattern: 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 5 = 47 months, or approximately 3.9 years, after a total or near total eclipse, an almost identical eclipse occurs.
Then, as time passed, these cultures discovered even more patterns. The Babylonians, for example, noticed that after A + A + B + B + B + B, or 223 months (18.5 years), another identical sequence of eclipses occurs, called the Saros cycle.

All of these patterns, which obey the laws of planetary motion, were obtained by simply observing the sky with the naked eye, so it is quite possible or even probable that the Mayan, Chinese and Babylonian cultures used the 6/5 rhythm to predict eclipses in prehistoric times, before the advent of writing. records. “I have no doubt that people could have done this for several thousand years [до этого] and transmit this information by word of mouth,” says Aveni.

Carving on tours

The oldest surviving image of an eclipse may be that from the megalithic cemetery of Loughcrew, also known as the “Witch Hills”, located near Oldcastle, Ireland. Neolithic passage tombs marked with large tourswere built in the fourth millennium BC – thus, they are almost a millennium older than Stonehenge.

While exploring one of the aurora in 1999, archaeoastronomer Paul Griffin discovered stone carvings of intersecting concentric circles that he believed could represent an eclipse. He established that an almost total eclipse occurred at Loughcru on November 30, 3340 BC. e., around the time when the tours were built; this makes it plausible that the carving, called a petroglyph, actually depicts an eclipse. But this is impossible to prove, and Aveni says that any number of meanings can be assigned to concentric circles.

Dragon Bones and Oracle Bones

Several thousand years later, the oldest verifiable records of solar eclipses were excised in Anyang, China. This city, then called Yin, was the capital of the ancient Shang Dynasty (1600-1045 BC), the first Chinese period to leave behind written documents. This heritage was rediscovered relatively recently, in 1899, when a pharmacist from Anyang gave the antiquarian and philologist Wang Yirong a recipe for a traditional remedy made by grinding “dragon bones.” Wang was about to grind the bones when he noticed that they were decorated with ancient Chinese inscriptions. These were not dragon bones, but oracle bones: ox shoulder blades and tortoise shell, which were once used to predict the future. The artifacts were eventually traced to a site near Anyang, where some 50,000 inscribed oracle bones have since been discovered, dating back to 1400-1200 BC.

“Divination played an extremely important role at that time,” says Xueshun Liu, a Chinese professor in the Department of Asian Studies at the University of British Columbia. These bone inscriptions are the oldest known documents in Chinese, and they include descriptions of eclipses. During the Shang Dynasty, when an eclipse was approaching, specially marked oracle bones were placed on the fire; when heated, small cracks appeared, which were believed to be messages from deceased ancestors. A diviner, or oracle, would then interpret the cracks and write prophecies on the bones.

On one of the many oracle bones where the eclipse is mentioned, it is written: “The king, having read the crack, said: “There will be harm.” Another simply reads: “The sun was eaten.”

Dark, spewing sun

At any location on the earth's surface, on average, only one total solar eclipse occurs every 375 years, lasting only a few minutes. Even more rarely, it coincides with another solar event called a coronal mass ejection, or CME. This occurs when giant bubbles of plasma and magnetic field burst out of the sun's corona, or outer atmosphere. Such emissions can be visible to the naked eye during a total solar eclipse, when the Moon covers everything except the solar corona.

“CMEs are not that uncommon. We see several throughout the day, especially during solar maximum,” or the peak of the Sun's 11-year cycle of activity, says C. Alex Young, associate director for science in the Heliophysics Science Division at the Space Center. NASA Goddard Flights. But he notes that the likelihood of one of them coinciding with “four or so minutes of eclipse is slim.”

However, it is possible that the ancient pueblos of Chaco Canyon, a city that flourished in 850-1250. n. e., could have witnessed such a spectacle. Proof of this is the Piedra del Sol, or “Rock of the Sun,” a large boulder in what is now New Mexico, on which numerous Chaco astronomical markers have been inscribed, previously identified. In 1992, solar astronomer Kim Mulville was helping lead a three-week field trip for college students when he “noticed an unusual petroglyph” on a boulder. It looked like the sun was spewing rays. What's more, “a depression was made where Venus would be,” says Maleville, professor emeritus of astrophysical and planetary sciences at the University of Colorado. Venus may be visible during the eclipse.

After reviewing a list of historical eclipses, Mulville discovered that only one total solar eclipse—June 29, 1097—occurred during the heyday of Chacoan culture. Several years later, solar physicists confirmed that the 1097 eclipse occurred during a period of high solar activity, making an eclipse-CME tandem more likely.

This year on April 8, eclipse watchers in North America had an equally high chance of seeing a CME, as the Sun is now at its peak and ejecting plasma several times a day. “Although the chances of seeing a coronal mass ejection coinciding with an eclipse are rare, they are now much higher,” Young says. “I've been studying these phenomena for 20 years, and the thought of seeing this from Earth with my own eyes would be truly amazing.”

Looking beyond the lens

When trying to understand how past peoples perceived the world, it's important to look through the lens of our modern culture, which is often dominated by the West, says Aveni, who began his career as an astronomer before moving into space studies through anthropology and Native American studies.

“We have to be very careful and look at all the cultures that came before us and realize that they were completely different,” says Aveni. “They took a completely different path than Western eclipse science. Sometimes our questions may be wrong. Did they know that the Earth is round? Did they know about the galaxy? According to him, these are not the questions that need to be asked. “They didn't live in our world.”

And we do not live in their time. With our ultra-precise clocks and compasses, we can often forget about the sky altogether, which was unthinkable for many peoples of the past. “When it comes down to it, other cultures have done things differently than we do,” Aveni says. “And that's what makes studying them so fun.”