Ancient Chinese text reveals the earliest known mention of a candidate aurora
There’s rarely time to write about every cool science story that comes our way. That’s why we’re posting a special Twelve Days of Christmas series of posts again this year, highlighting one science story every day from December 25 to January 5 that fell through the cracks in 2022. Today: New analysis of an ancient Chinese text revealed the earliest candidate aurora yet found, three centuries older than the next oldest.
A pair of researchers have identified the earliest description of a candidate aurora yet found in an ancient Chinese text, according to a April paper published in the journal Advances in Space Research. The authors link the likely date of the event to 977 or 957 BC. The next earliest description of a candidate aurora is found on Assyrian cuneiform tablets dated between 679-655 BCE, three centuries later.
Like we did previously reportedare the spectacular kaleidoscopic effects of the so-called northern lights (or southern lights if they are in the southern hemisphere) the result of charged particles from the sun being dumped into the earth magnetosphere, where they collide with oxygen and nitrogen molecules – an interaction that excites those molecules and makes them glow. Auroras are usually present as shimmering ribbons in the sky, with shades of green, purple, blue and yellow.
There are several types of auroral displays, such as “diffuse” auroras (a faint glow near the horizon), rarer “pegs” and “dune” appears, and “discreet aurora arcs” – the most intense variety, appearing in the sky as shimmering, billowing curtains of light. Discreet aurora arcs can be so bright it’s possible to read a newspaper by their light. That was the case in August and September 1859, when there was a great geomagnetic storm, or the carrington event, the largest ever recorded— which produced dazzling auroras visible in the US, Europe, Japan and Australia.
The Bamboo annals is a chronicle of ancient China, written on bamboo strips, beginning with the age of the Yellow Emperor and passes through the Warring States period (5th century – 221 BCE), when rival states engaged in fierce competition. It ended when the state Qin united the states. The original text of the Bamboo annals was buried with King Xiang of Wei, who died in 296 B.C., and was not crowned until 281 A.D. burning the books in 212 BCE (not to mention burying hundreds of Confucian scholars alive).
The original text consisted of 13 scrolls that were lost during the Song dynasty (AD 960–1279). There are two versions of the Bamboo annals still exist. One is known as the ‘current text’, consisting of two scrolls printed in the late 16th century. Many scholars believe this text to be a forgery, given the many discrepancies between the text and parts of the original quoted in older books, although some scholars have argued that some parts could be faithful to the original text. The other version is known as the “ancient text” and was pieced together by studying the aforementioned quoted portions in older books, especially two dating back to the early 8th century AD.
Independent researcher Marinus Anthony van der Sluijs and Hisashi Hayakawa of Nagoya University relied on the ancient text for their new analysis. This text describes the appearance of a “five-colored light” visible in the northern part of the night sky towards the end of the reign of King Zhao of the Zhou dynasty. Auroras are usually only visible in polar regions because the particles follow the Earth’s magnetic field lines, which fan out from near the poles. But powerful geomagnetic storms can cause the auroral ovals to expand to lower latitudes, often accompanied by multicolored lights. According to the authors, Earth’s North Magnetic Pole was about 15 degrees closer to central China in the 10th century BCE than it is today, so the people there may have witnessed such displays.
While technically an unconfirmed candidate aurora, “the explicit mention of nocturnal observation precludes daytime manifestations of atmospheric optics, which sometimes mimic candidate events,” the authors wrote. In addition, “The appearance of a multi-colored phenomenon in the northern sky during the night is consistent with visual auroral displays in mid-latitude regions.” According to van der Sluijs and Hayakawa, the 16th-century current text translation of the passage in question described the event as a “comet” rather than a “five-colored light”, which is why the candidate aurora has not yet been identified. .
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