Colorful light phenomena around 3000 years ago: A research team interprets the description of a celestial event in an old Chinese text as the earliest historical indication of an aurora. In addition to the historical significance, the information could also be useful in modeling long-term patterns in variability in space weather and solar activity, the scientists say.
Colorful luminous phenomena meander across the sky and envelop the world in magical splendour: the northern lights have always fascinated people and inspired mythical explanations. They flowed into the legends and stories of the Nordic peoples, because the luminous phenomena can be observed particularly frequently and distinctly in the polar region. What was once described as mythical and religious now has a scientific explanation: the light effects are due to an interplay between the solar wind, the earth’s magnetic field and the air. The high-energy particles stimulate nitrogen and oxygen atoms to glow. This occurs particularly in the polar regions because there the lines of the earth’s magnetic field penetrate the atmosphere. However, after particularly pronounced solar flares that trigger particularly intense solar winds, the lights can also be visible further south.
Reference in the ancient Bamboo Annals
There, the celestial phenomena cause a special stir – and that was also the case in the past, as reflected in the historical records of various cultures. The oldest known reference to date are records on Assyrian cuneiform tablets from the period 679 to 655 BC. However, as the Japanese University of Nagoya reports, a team of researchers has now identified a historical description that they interpret as referring to an aurora that occurred about 300 years earlier. It comes from the so-called Bamboo Annals – a chronicle of the history of China before the founding of the empire. It records various events from before its likely writing, in the 4th century BC. Chr.
Although this chronicle has been known for a long time, a special look at some passages can still provide new clues. According to the university, in addition to historical events, the text also mentions unusual observations of nature in some places. The scientists now have their sights set on a passage that speaks of a celestial phenomenon in central China, which they translate as “five-colored light”. According to the context, it was sighted in the northern part of the sky. There are also chronological indications: The phenomenon appeared accordingly in a night at the end of the reign of King Zhao of the Zhou Dynasty. This put it back to the early 1st millennium BC. narrow down. However, since the end of Zhao’s reign is dated differently, according to the scientists, there are two possible years of appearance: 977 and 957 BC. Chr.
Did a multicolored aurora shine over China?
They explain that the “five-colored light” suggests it was an aurora that appears to have occurred in the wake of a powerful solar flare followed by an intense particle storm. Because it is known that a spectacle of several colors can arise if the northern lights are sufficiently bright in the middle latitudes. The scientists cite similar descriptions from other historical records, which, however, are much closer to our time. If their interpretation of the “five-colored light” as an aurora is correct, the researchers conclude that the text from the Bamboo Annals is the earliest datable record of an aurora borealis.
According to them, the fact that the celestial phenomenon was so clearly visible in the region quite far to the south could have been linked to the position of the Earth’s magnetic north pole at that time: In the 10th century B.C. It is known to have been about 15 degrees closer to central China than it is today. Therefore, the northern lights could also have been clearly visible there at times of significant magnetic disturbances, the researchers explain.
As the University of Nagoya concludes, the historical trail has more than historical significance: such clues can help scientists model long-term patterns in space weather variability and solar activity. Understanding these fluctuations can, in turn, help prepare for future large-scale solar flares. Because the effects of strong solar storms can cause significant disruptions to the technical infrastructure. Around 3000 years ago, at least, that was not a problem. But one can well imagine how people puzzled back then what the colorful appearances in the sky meant.
Source: University of Nagoya