E-LETTER Earth Planets Space, 56, e41–e44, 2004 Understanding the “SEKKI ” phenomena in Japanese historical literatures based on the modern science of low-latitude aurora

“SEKKI ” phenomena often appear in the Japanese historical literatures as distinct red emission in the nocturnal sky. The Japanese word “SEKKI ” means the red atmosphere. We compile 16 events of SEKKI for 12–19th centuries in the literatures. In order to understand the SEKKI phenomena, we compared 2 events of SEKKI on February 21, 1204, and September 17, 1770, with the characteristics of low-latitude auroras studied recently by modern scientific methods. We conclude that these historical SEKKI phenomena are probably giant low-latitude auroras. Key words: SEKKI, low-latitude aurora, historical literatures, magnetic storm. 1