‘Vapours like fire light’ are Korean aurorae

Abstract

The chronicles of Korea are unique in recording frequent observations of a featureless red glow in various directions in the night sky. Often there are 10 or more of these sightings in a year. The frequency is much higher than might be expected for auroral observations at such a low geomagnetic latitude (around 30°N). In this paper, as a pilot survey, we make a careful study of some four years of observations (1625–1628). These are recorded in two extensive Korean chronicles. We conclude that the observations are genuine and they represent much more than merely extended sunset or sunrise glows. Since these observations are found to be more frequent at the vernal equinox and also at new Moon, we believe that they are indeed auroral observations.