Ancient Swedish Goths had surprisingly accurate calendars

On a mostly flat plain an hour north of Stockholm lies a collection of large burial mounds dating from an ancient culture at least 2,500 years old. These people were not Vikings; they were northern Germanic Goths, pagan polytheists worshiping the precursors of Odin, Freyr and Thor.

In truth, this ancient subgroup of Goths could probably have cared less about astronomy as we know it today. Yet, inexplicably, they were driven to make precise measurements of the sun and moon. They were obsessed with precisely timing nine days of gruesome midwinter human and animal sacrifices. Despite such barbarism, they apparently believed that if they did not make these great midwinter sacrifices every eight years, the following eight years might bring a catastrophe.

The sacrifices usually began at the height of winter from Feb. 6–8. And at least one contemporary Swedish astrophysicist claims to have found these Goths’ sacrificial calendar.

“I have discovered the calendar that regulates the dates for the Great Midwinter Sacrifice that took place every eight years,” Goran Henriksson, an astrophysicist and former lecturer at Uppsala University in Sweden, tells me in Uppsala. In 2014, archaeologists discovered two long rows of poles that marked the northern limit for the rising of the full moon and the direction of the rising sun when it was time to start a sacrificial cycle, Henriksson tells me.

“The sacrifice at Old Uppsala took place every eighth year; the starting date was defined by the full moon that occurred between Jan. 28 and Feb. 26 in the Gregorian calendar,” Henriksson writes in a paper presented at the 2014 meeting of the European Society for Astronomy in Culture. By combining historical data and calculations of the dates of full moons, Henriksson has established the exact years of the eight-year cycle, including one that began in AD 852.

As for today?

Uppsala is a contemporary Swedish city only a short distance from Arlanda international airport. But walking through these hills on a windy July afternoon, one can only imagine Visigoth culture as it once was. These people obviously had an appreciation of the natural world—including the celestial sphere—that completely eludes us at present.

Royal burial mounds

Three “royal” burial mounds have been dated to AD 450–550 and oriented in such a way that they could have been used to regulate the sacrificial calendar, Henriksson writes. During archaeological excavations in 2013, two long rows of postholes were discovered, he writes.

An 850-meter-long (2,800-foot-long) row was oriented toward the northern limit for the rising midwinter full moon on the earliest date, Henriksson notes in his paper. The approximately 600-meter-long (2,000-foot-long) row was oriented toward the rising sun from Feb. 6 through 8, he writes.

In fact, this sacrifice took place according to an eight-year cycle determined by the phases of the moon, which they could measure to six digits of accuracy. For a period of nine days, one man and seven male domestic animals were sacrificed. And when the sacrifices were complete, one could see 72 bodies hanging upside down in a holy tree.

Incredibly, these burial mounds, which today are surrounded by at least 100 square miles (260 square kilometers) of flat plain, were at the time less than half a mile (0.8 kilometer) from what we now call the Baltic Sea. At that time, local sea level was 19.5 meters (64 feet) higher than it is today.

“The rays of the sun were reflected in the sea on both sides of the posts, and the shadows from the posts were aligned with the row,” Henriksson writes. “It was a magnificent and very precise way to determine the correct date for the great midwinter sacrifice,” he notes.

A precision calendar

“They had a very sophisticated calendar here,” says Henriksson. “The poles determined very accurately when it was a full moon and when the sun was rising along this 600-meter-long row of poles, and when they should start the next great sacrifice,” he says.

These Goths thought that it was necessary to make sacrifices to the gods to ensure order and good times for another eight years. And, ironically, they had a more precise calendar than the Catholic Church did hundreds of years later.

Above all, despite their strange behavior, it’s arguably their religious beliefs and belief in an afterlife that drove their quest for precision calendrics.

“A preliminary investigation shows that the boats are oriented toward the rising full moon of the Great Midwinter Sacrifice in the eight-year cycle,” Henriksson writes in his paper. “The most remarkable type of grave contains a warrior with full equipment, including a horse, buried in a boat,” he notes. Fifteen such boat graves from AD 550–1100 have been investigated, he writes.

“They wanted their dead chieftains to have everything they thought would be needed in an afterlife, including a horse, dogs and even a complete kitchen,” says Henriksson.

But why did they orient it toward the moon?

“The moon was very important to them; it was a Goth god,” says Henriksson.

Who’s behind this story?

Lisa Lock

BA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021.

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Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

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