Historical Auroras in the 990s: Evidence for Great Magnetic Storms

TL;DR

This study examines historical records of auroras from the 990s to provide evidence of intense solar activity and magnetic storms, correlating with a significant carbon-14 event in 994 suggesting a large cosmic ray flux.

Contribution

It presents new and previously reported aurora records from the 990s, supporting the occurrence of great magnetic storms linked to solar activity during that period.

Findings

Potential auroras recorded in Korea, Germany, and Ireland in 992-993.

Evidence supports a link between auroras and a large cosmic ray event in 994.

Historical aurora records indicate intense solar activity in the 990s.

Abstract

Recently, a significant carbon-14 enhancement in the year 994 in tree rings has been found, suggesting an extremely large cosmic ray flux event during a short period. The origin of this particular cosmic ray event has not been confirmed, but one possibility is that it is of solar origin. Contemporary historical records of low latitude auroras can be used as supporting evidence for intense solar activity around that time. We investigated the previously reported as well as the new records found in contemporary observations from the 990s to determine potential auroras. Records of potential red auroras in the late 992 and early 993 were found around the world, i.e. in the Korean Peninsula, Germany, and the Island of Ireland, suggesting the occurrence of an intense geomagnetic storm driven by solar activity.