An ancient Chinese text reveals the oldest known record of the aurora borealis

Zoom in / Aurora borealis displayed over snow-capped mountains in Hangzhou, China.

Liu Ming Sun/Getty Images

There is rarely time to write about every great science story that comes our way. So this year, we’re once again running a special “The Twelve Days of Christmas” series of posts, highlighting one science story that fell through the cracks in 2022, every day from December 25th to January 5th. Today: A new analysis of an ancient Chinese text has revealed the first candidate diagonal aurorae to date, predating the earliest by three centuries.

A pair of researchers located the oldest candidate description of the aurora borealis to date in an ancient Chinese text, according to a paper published in April in the journal Advances in Space Research. The authors peg the possible date of the event to either 977 or 957 BC. The next oldest description of the aurora borealis is found on Assyrian cuneiform tablets dated between 679-655 BC, three centuries later.

As mentioned earlier, the amazing changing effects of the so-called northern lights (or southern lights if you’re in the southern hemisphere) are the result of charged particles from the sun being hurled into Earth’s magnetosphere, where they collide with molecules of oxygen and nitrogen—an interaction that excites those molecules and makes them glow. The aurora borealis usually appear as shimmering bands in the sky, in hues of green, purple, blue, and yellow.

There are different types of auroral displays, such as “diffuse” aurora (a faint glow near the horizon), rare “hedge-hog” and “dune” displays, and “discrete arcs”—the most intense type that appears in the sky as shimmering, undulating curtains of the light. Discrete aurorae arcs can be so bright, it is possible to read a newspaper by their light. Such was the case in August and September of 1859, when a great geomagnetic storm—aka the Carrington event, the largest ever recorded—produced dazzling aurorae visible across the United States, Europe, Japan, and Australia.

the Bamboo Annals It is a historical account of ancient China, written on bamboo strips, that begins with the era of the Yellow Emperor and extends through the so-called Warring States Period (5th century – 221 BC), when rival states were engaged in intense competition. And it ended when the state of Qin unified the states. The original text of Bamboo Annals Buried with King Xiang of Wei, who died in 296 BC, it was not discovered until 281 AD, thus Emperor Qin Shi Huang escaped the book burnings of 212 BC (not to mention hundreds of Confucian scholars were buried alive).

Bamboo Annals. “> Bamboo Annals. “src=”https://cdn.arstechnica.net/wp-content/uploads/2022/04/aurora1-640×437.jpg” width=”640″height=”437″srcset=”https://cdn.arstechnica.net/wp-content/uploads/2022/04/aurora1-640×437.jpg” arstechnica.net/wp-content/uploads/2022/04/aurora1.jpg 2x”/>
Zoom in / Various fragments of Bamboo Annals.

MA van der Sluijs & H. Hayakawa, 2022

The original text consisted of 13 manuscripts that were lost during the Song Dynasty (AD 960-1279). There are two versions of the program Bamboo Annals still in existence. One is known as the “current text”, and consists of scrolls that were printed in the late sixteenth century. Many scholars believe this text to be a forgery, given the many discrepancies between its text and parts of the original quoted in ancient books, although some scholars have argued that some parts may be faithful to the original text. The other version is known as the “Ancient Text,” and was pieced together by studying the above-quoted fragments found in ancient books, especially two books dating from the early eighth century CE.

Independent researcher Marinus Anthony van der Slweg 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 near the end of King Zhao’s reign of the Zhou dynasty. Aurorae tend to only be visible in the polar regions because the particles follow Earth’s magnetic field lines, which radiate from the vicinity of the poles. But strong geomagnetic storms can cause auroral ovals to stretch out to lower latitudes, often accompanied by multicolored lights. According to the authors, during the 10th century BC, Earth’s north magnetic pole was about 15 degrees closer to central China than it is today, so people there may have witnessed such displays.

While this is technically an uncertain candidate aurora, the authors write: “The explicit indication of nighttime observation excludes daytime appearances of atmospheric optics, which sometimes mimic candidate events.” Furthermore, “the occurrence of a multicolored phenomenon in the northern sky during the night is consistent with auroral displays visible in mid-latitudes.” According to van der Sluijs and Hayakawa, the current 16th-century text translation of the passage in question described the event as a “comet”, not as a “pentachromatic light”, and for this reason the candidate aurora has not yet been identified.

DOI: Advances in Space Research, 2022. 10.1016/j.asr.2022.01.010 (about DOIs).

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