Ancient Goths tracked Moon with precise calendar

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Archaeologists in Sweden discovered evidence that people identifying as Goths, who lived at least 2500 years ago, used a sophisticated calendar to time religious sacrifices.
Goran Henrikson, an astrophysicist at Uppsala University, studied burial mounds north of Stockholm and found rows of poles aligned with the rising full Moon and Sun. These alignments marked the start of an eight-year sacrificial cycle, typically occurring between February 6 and 8.
The Goths sacrificed one man and seven animals during a nine-day period, believing these offerings prevented catastrophe in the following eight years. Henrikson determined they could measure the phases of the Moon with six-digit accuracy, using the poles to reflect sunlight and align shadows. He traced one cycle back to 852 A.D. through historical data and calculations of full moon dates. The burial mounds themselves, dating to 450-550 A.D., may have also functioned as part of the calendar system.
Fifteen boat-graves from the same period contained warriors buried with horses, dogs, and other goods, oriented towards the rising full moon. At the time the Goths built the mounds, the Baltic Sea’s water level was 19.5 meters higher than it is today, and the mounds were less than half a mile from the shoreline.

