Watching a space rock sail by the planet without hitting it is usually cause for breathing a sigh of relief – but new research into the pre-Columbian Hopewell culture in what is now Ohio shows that a near-hit by a comet around 1500 years ago may have caused them to breath their last breaths as fiery debris and extreme heat rained down upon them. While their demise was not instantaneous, the comet tail tragedy may have been the inspiration for a comet-shaped mound in what is now called the Milford Earthworks.
“Between 1,800 and 1431 years ago (220 and 589 CE), Chinese astronomers documented 69 near-Earth comets, including Haley’s, which came within 0.09 au of earth in 374 CE. At this time, human communities and the resources they needed for survival were at a heightened risk of being destroyed by a comet airburst event.”
In a new study published in the journal Scientific Reports, researchers from the University of Cincinnati used that data from Chinese astronomers and went looking for evidence of comet tail debris impacts in the U.S. The found it 11 Hopewell archaeological sites in three states stretching across the Ohio River Valley. The evidence included an unusually high concentration and diversity of meteorites containing iridium and platinum, and a charcoal layer suggesting an airburst caused fires across 9,200 square miles sometime between the years 252 CE and 383 CE. This coincides with the near-Earth comets documented by the Chinese astronomers, tales of fiery objects in the sky in many Native American oral histories, and the beginning of the mysterious disappearance of the Ohio Hopewells.
"The Miami tell of a horned serpent that flew across the sky and dropped rocks onto the land before plummeting into the river. When you see a comet going through the air, it would look like a large snake. The Shawnee refer to a 'sky panther' that had the power to tear down forests. The Ottawa talk of a day when the Sun fell from the sky. And when a comet hits the thermosphere, it would have exploded like a nuclear bomb. And the Wyandot recount a dark cloud that rolled across the sky and was destroyed by a fiery dart."
Anthropologist and lead author Kenneth Tankersley reveals in a University of Cincinnati press release how other Native American cultures told the tale of these comets. These were the members of the Hopewell culture or tradition – a diverse and dispersed set of native populations connected by a common network of trade routes that once stretched from Lake Ontario to the Crystal River Indian Mounds in modern-day Florida. Part of that trade route passed through a New Jersey-sized area surrounding the confluence of the Ohio and Great Miami rivers where the bulk of the meteorites and fire damage was found.
“It looks like this event was very injurious to agriculture. People didn’t have good ways to store corn for a long period of time. Losing a crop or two would have caused widespread suffering. When your corn crop fails, you can usually rely on a tree crop. But if they’re all destroyed, it would have been incredibly disruptive.”
UC biology professor and study co-author David Lentz says the evidence shows a complete destruction of the corn crops the natives were growing and the nut trees they depended on in the forests. Lentz pictures the destruction of the trees being similar to the devastation seen in photos of the Tunguska event in Siberia in 1908.
Archeologists believe the Hopewell tradition ended around 500 CE as evidenced by the end of mound building. Why it ended has been a mystery – there were signs of fortification indicating it could have been a war. This was also a time of climate change, which affected both hunting and agriculture and may have impacted trading. Now there’s the evidence of a near-hit comet spreading destruction across vast areas of the Hopewell exchange. Could that be the ultimate reason for its demise?
“It’s hard to know exactly what happened. We only have a few points of light in the darkness. But we have this area of high heat that would have been catastrophic for people in that area and beyond.”
The next step is to study the layers of soil in the area for pollen from that time period which could show how a fiery airburst altered the agricultural landscape and plant life.
The members of the Hopewell tradition who survived the blast of a comet’s tale managed to live for another 1000 years until they were hit by a burst even more deadly – Europeans.