Analyses of historical solar eclipse records in Hokkaido Island in the 18–19th centuries

Abstract

Abstract Solar eclipses have been recorded throughout history and across various ethnic groups. Their records have benefitted scientific discussions on multiple topics. These astronomical spectacles have also been recorded in the Japanese archipelago, but little has been known of the historical observations in the northern end: Hokkaido Island (known as Ezo Island until 1869). Here, we analysed three such early eclipse accounts from Hokkaido Island, both philologically and astronomically. We first analysed Tokunai Mogami's eclipse account written in 1786 January, which has been associated with the earliest eclipse record in Hokkaido Island. Our analysis showed that this eclipse was a deep partial solar eclipse outside the annular totality path of a hybrid eclipse, whereas it had previously been associated with an annular solar eclipse. This eclipse was also witnessed in the Ryukyu Kingdom, probably as a deep partial eclipse. We also located eclipse sketches in Kan’ichiro Mozume's diary and confirmed the local visibility of the annular eclipse in Otaru in 1872 June. We further analysed John Batchelor's eclipse folklore and identified the reported eclipse with a total solar eclipse in 1824 June. This folklore reported “tongues of fire and lightning” from the side of the “black dead sun.” This description is morphologically consistent with that of solar coronal streamers around the solar minima. This eclipse is chronologically located around the minimum of Solar Cycles 6/7 and contrasts the Dalton Minimum with the Maunder Minimum, for which coronal streamers were reportedly missing, according to visual observations.