Unusual rainbows as auroral candidates: another point of view

TL;DR

This paper investigates historical reports of unusual rainbows in Europe and South America, proposing they are potential auroral events, thereby expanding auroral catalogues with new terminology across different cultural sources.

Contribution

It demonstrates that terms like 'unusual rainbow' can be applied to European and South American historical events, broadening auroral records beyond oriental sources.

Findings

Historical rainbows in Europe and South America match auroral descriptions.

The terminology used in oriental chronicles is applicable to occidental records.

Auroral catalogues can be extended with new terminology for diverse sources.

Abstract

Several auroral events that occurred in the past have not been catalogued as such due to fact that they were described in the historical sources with different terminology. Hayakawa et al. (2016) have reviewed historical oriental chronicles and have proposed the terms "unusual rainbow" and "white rainbow" as candidates to auroras. In this work, we present three events that took place in the 18th century in two different settings (the Iberian Peninsula and Brazil) that were originally described with similar definition/wording used by the oriental chronicles, despite the inherent differences in terms associated to oriental and Latin languages. We show that these terms are indeed applicable to the three case studies from Europe and South America. Thus, the auroral catalogues available can be extended for occidental sources with this new terminology.