Ancient Assyrian stone tablets represent the oldest known reports of auroras, dating back more than 2,500 years ago.
The descriptions, written in cuneiform, were found on three stone tablets from 655 BC. to 679 B.C. They predate other known historical references to auras about a century, researchers reported in a new study.
Auroras are dazzling light displays that take place when waves of charged particles from the sun collide with the Earth's magnetic field. The earth was probably visited by a huge solar storm around the seventh century BC, and the auroras described in the tablets may have been the result of the vigorous solar activity, wrote author studies online October 7 The Astrophysical Journal Letters .
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Ancient sky-gazing accounts, like those on these Assyrian tablets, help scientists put together a more complete picture of the Earth's cosmic tango with its solar partner. Since telescope observations have been around for only 400 years, they provide "only a very small snapshot at best" of how our sun behaves, said lead study author Hisashi Hayakawa, an astrophysicist at Osaka University in Japan and a visiting scientist at Rutherford Appleton Laboratory in the United Kingdom.
Earlier this year, another research group found that a massive solar storm, about 1
The authors of the new study wondered if Assyrian astrologers from that period may have registered something unusual that could be linked to the solar storm . The researchers examined 389 reports of gender-shaped tablets in the collection of the British Museum; most of the reports described planetary and lunar activity. But three items noted phenomena that were likely candidates for auroras: "red glow," "red cloud" and "red sky," according to the study.
"These descriptions themselves are quite consistent with the early modern descriptions of auroral display," Hayakawa told Live Science in an email. In fact, red is a color commonly found in low altitude auroras and in auroras produced by low-energy electrons, the researchers reported.
Today auroras in the Northern Hemisphere are usually associated with regions near the North Pole. But the Earth's magnetic field is dynamic and changeable, and thousands of years ago, the magnetic north was about 10 degrees closer to the Middle East than it is today, increasing the likelihood of spectacular aurora screens in that part of the world, study authors reported.
And even in the late 19th century, auroras were still obscured in Cairo; Baghdad; and Alexandria, Egypt, added Hayakawa.
"When you have significant magnetic storms, it is not something extremely surprising to see auroras in the Middle East, not even in the (early) modern period," Hayakawa said.
The rarity of these descriptions in the Assyrian records suggests that what the writers had witnessed was something unusual and not, for example, a red sky that could follow a lively sunset, Hayakawa said.
Prior to this discovery, the earliest known reference to an aurora in was a Babylonian tablet known as "Astronomical Diaries", dated to 567 BC. The Assyrian data "allow us to trace the history of solar activity a century earlier than the earliest existing datable auroral reports," according to the study.
Originally published on Live Science .