Journal Highlights

Historical space weather monitoring of prolonged aurora activities in Japan and in China

Editors’ Highlight—The authors describe a deep search for prolonged intervals of low-latitude aurora sightings in the records extracted from Japanese and Chinese documents dating as far back as the year 510 CE. A particularly noteworthy event was documented in Japan in late February 1204 CE. The authors report that a significant fraction of the 200 possible low-latitude aurora sightings in the Song Dynasty of China (960-1279) were detected at least twice within a seven-day interval. The authors further argue that such events are the likely results of homologous coronal mass ejections. Combining data from other studies with new data generated in this study, the authors argue that all but one of the prolonged low-latitude events occurred in either solar maximum or solar cycle decline. Translations of the auroral records indicate that appearance of low-latitude aurora were distressing to the observer(s) and, in at least one case, caused the observer to delay travel plans to avoid any adverse effects of such a "dreadful" event. In addition to the fascinating account of these events, the reference list for this study is an important compilation of historic aurora reports.