Ancient Assyrian Aurorae Help Astronomers Understand Solar Activity

On a dark spring night, the sky blanketing the Neo-Assyrian Empire turned red. The “red glow” was taken as an ominous sign—one important enough that the Assyrian court scribe Issār-šumu-ēreš carved an official record of the event into a clay tablet. This Neo-Assyrian tablet from the Library of Ashurbanipal provided researchers with what may be one of the earliest descriptions of the aurora borealis. Although the event, which we know today as the aurora borealis or northern lights, wouldn’t have affected the course of nature at the time, it is now helping astronomers understand our Sun and may even help protect astronauts and assets in space.

The Assyrian record is thought to be one of the earliest known observations of aurorae, dating to around 660 BCE. Aurorae are created by high-energy particles launched from the Sun, and historical records offer a way to study conditions on the Sun long before the invention of telescopes. “Direct observations [of the Sun] span some 400 years with sunspot observations, and ground-based instrument observations are mostly within 200 years,” said Hisashi Hayakawa, lead author of a new study and an astronomer at Osaka University in Japan and the Rutherford Appleton Laboratory in the United Kingdom. “To discuss the kind of less frequent, but more hazardous events [coming from the Sun], we need to expand the data coverage, like with historical documents.”

RadioUser reports regularly on how solar phenomena affect the propagation of radio waves in the modern era, and also has a dedicated history column each month.

https://tinyurl.com/sjdsbvc

(Source: EoS: Earth and Space Science News, 2019; The Trustees of the British Museum, CC BY-NC-SA 4.0) Citation: Johnson-Groh, M. (2019), Ancient Assyrian aurorae help astronomers understand solar activity, Eos, 100, https://doi.org/10.1029).

Georg Wiessala

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