In the Annals of Bamboo, a chronicle of Chinese history, a “five-colored light” that researchers believe is the first record of an aurora borealis is described.
Polar lights are one of the most striking natural phenomena that exist. These lights result from the interaction of the solar wind, that is, the flow of charged particles coming from the Sun, with the Earth’s magnetic field in the layer known as the magnetosphere.
The usual thing is to feed the auroras at the poles, as large amounts of high-energy charged particles are concentrated there. Thus, solar radiation easily penetrates the atmosphere and gives rise to the polar auroras, which are called borealis in the northern hemisphere and australis in the southern hemisphere.
Colors arise from the excitation of different atoms in the atmosphere. Green and yellow tones appear when oxygen reacts with the solar wind. Blues are produced by interaction with nitrogen, and mixing these colors gives rise to pinks and whites.
Humans have witnessed this colorful spectacle for centuries. In 679 BC, astronomers in Assyria, a region of Mesopotamia in what is now Iraq, described possible sightings of aurora on clay tablets with cuneiform inscriptions. Some scientists have also interpreted the prophet Ezekiel’s vision in 594 BC as a probable dawn. A little later, in 576 BC, what could have been the appearance of an aurora was noted in the astronomical diary of Babylonian king Nebuchadnezzar II.
Does “five-color light” mean aurora?
A recent post about Advances in Space Research magazine concludes that the earliest reference to an aurora is found in the Bamboo Annals (Zhushu Jinian in Mandarin) dated 977 BC or 957 BC This text brings together the history of China from mythical rulers such as the Yellow Emperor, called Huangdi, to the states that ended with the unification of the states that formed China in the 5th century BC
In these chronicles, astronomical observations are not common, but a “five-colored light” is mentioned. Supposedly, it was seen in Hao Jing, present-day Xi’an, in northwest central China, in 977 or 957 BC, at the end of the Zhao kingdom of the Zhou dynasty. The exact year is unknown because it varies according to the chronologies: that of Edward L. Shaughnessy, an expert in ancient Chinese studies and a researcher at the University of Chicago (USA), and the Xia-Shang-Zhou Chronology, a project commissioned by the People’s Republic of China to determine the Xia, Shang and Zhou dynasties.
These findings help establish patterns in variations in space weather and solar activity over the past few millennia.
The official account of the Annals of Bamboo has been difficult to preserve. The original manuscript was lost, discovered in the 3rd century and disappeared again during the Song dynasty between 960 and 1279. Although some of the contents have been preserved by the copies that were made of it. A new version of the original text was published in the 16th century.
In the old edition, there is a “five-color light that entered Zǐwēi» (sky deity) at night. However, in the new one, it appears as a “blurred star”. The researchers of this study, Marinus Anthony van der Sluijs and Hisashi Hayakawa, chose the ancient version because they interpreted it as an aurora polar that appeared in the circumpolar region and was multicolored.
The authors relied on several reports showing that the north magnetic pole was located in the Eurasian zone 15° closer to China in the 10th century BC than it is today. Because of this, the aurora from the polar oval would have been visible.
Also, thanks to cosmogenic isotope reconstruction, it is known that between 977 BC and 957 BC a series of sunspots were produced that could cause the northern lights. This is discovered by analyzing how long a rock has been exposed to cosmic rays.
These findings help establish patterns in long-term space weather variations and solar activity for millennia. By understanding these fluctuations, we can better predict solar flares, which influence communications and weather, and be better prepared.