The earliest drawings of datable auroras and a two-tail comet from the Syriac Chronicle of Z=uqn=in

People have probably been watching the sky since the beginning of human history. Observers in pre-telescopic ages recorded anomalous events and these astronomical records in the historical documents provide uniquely valuable information for modern scientists. Records with drawings are particularly useful, as the verbal expressions recorded by pre-telescopic observers, who did not know the physical nature of the phenomena, are often ambiguous. However, drawings for specific datable events in the historical documents are much fewer than the verbal records. Therefore, in this paper, we show the possible earliest drawings of datable auroras and a two-tail comet in a manuscript of the Chronicle of Z=uqn=in, a Syriac chronicle up to 775/776 CE to interpret their nature. They provide not only the historical facts in the realm around Amida but also information about low-latitude aurora observations due to extreme space weather events and the existence of sun-grazing comets.

💡 Research Summary

The paper investigates ten astronomical illustrations found in the Syriac “Chronicle of Zūqnīn” (Vat.Sir.162), a manuscript dated to the late 8th century and preserved in the Vatican Library. By microscopic examination of ink colour (brown and red) and handwriting style, the authors demonstrate that the drawings were made by the chronicler himself, Joshua the Stylite, rather than being later marginalia. This conclusion is reinforced by explicit textual references to the images within the manuscript (e.g., “this is its shape” and “it is the shape of this sign that is drawn above”).

Geographically, the chronicle was composed in Amida (modern Mardin, Turkey) at a magnetic latitude of roughly 45° in the 8th century, a value derived from reconstructions of the geomagnetic pole over the past two millennia. The authors calculate that, to produce the observed low‑latitude auroral displays, the associated Dst index would need to be at least –365 nT, comparable to the extreme Halloween storm of October 2003. Such a storm would be exceptionally rare at these latitudes, indicating that the events recorded for 771/772 CE and 773 CE were truly extreme space‑weather episodes.

Illustrations 9 and 10 depict a series of coloured “scepters” (blood‑red, green, black, saffron) rising sequentially from the horizon upward. The authors interpret the colours as auroral emissions: red (OI 630 nm), green (OI 557.7 nm), black as a “black aurora” region, and saffron as a yellowish hue caused by atmospheric extinction of the green line near the horizon. The vertical strip pattern, described in the text as moving “from below to above,” matches the “flaming” motion typical of discrete auroral arcs. Additional contextual clues—references to “harvest time,” the month of ḥzīrān (June), and the day of the week (Friday)—allow a more precise dating of the 773 CE event to a specific Friday in June (the 3rd, 10th, 17th, or 24th).

A separate set of illustrations (not fully reproduced in the excerpt) describes a comet with two distinct tails extending in opposite directions. The morphology matches that of a sun‑grazing (sungrazing) comet, often referred to as a “two‑tail” or “sulphur‑tail” comet in modern terminology. Cross‑checking with contemporary East Asian (Chinese, Japanese) and Middle‑Eastern records reveals analogous comet sightings in the same period, supporting the identification of a genuine astronomical event rather than a mythic or symbolic description.

The authors place their findings in a broader historiographical context. While many medieval European and Chinese sources contain textual aurora or comet reports, visual depictions are scarce before the 16th century. The Zūqnīn drawings therefore constitute some of the earliest datable astronomical illustrations, providing a rare visual anchor that reduces the ambiguity inherent in purely verbal accounts.

Limitations acknowledged include the loss of folios covering 774/775 CE and 775/776 CE, which prevents direct verification of events in those years, and the inherent subjectivity in mapping medieval colour terminology onto modern spectral lines. The Dst estimate relies on an empirical formula (Yokoyama et al., 1998) and may over‑ or underestimate the true geomagnetic disturbance.

In conclusion, the study convincingly argues that the Syriac chronicle’s illustrations are authentic, contemporaneous sketches of extreme low‑latitude auroras and a sun‑grazing comet. These records expand the temporal baseline for extreme space‑weather events, demonstrate that 8th‑century observers in the Near East witnessed phenomena comparable to modern high‑intensity geomagnetic storms, and provide a valuable data point for reconstructing past solar activity and its terrestrial impacts.