South Korea's renewed focus on space weather

Abstract

Nearly 1000 years before European scientists David Fabricius and Galileo Galilei made historic observations of sunspots, royal astronomers in Korea were recording their observations of blemishes on the Sun. Sunspot records appeared as early as 640 C.E. in Korea [Yang et al., 1998], and records with statistically significant populations of data have been available since 1105 C.E. during the Goryeo dynasty (918-1392). The records are quite meticulous. For example, one entry dated 1151 in the annals of the Goryeo dynasty says, "There is a black spot in the sun as large as an egg" (Goryeo-Sa, 1451). At that time, sunspots were categorized according to size: plum, egg, peach, or pear. In Goryeo-Sa, various celestial phenomena such as solar eclipses, comets, novae, meteors, etc., were also recorded. Along with sunspots, aurorae were carefully described in several Korean chronicles, including Goryeo-Sa. Descriptions of aurorae, commonly referred to as "red energy," include their color, shape, motion, and distribution. For example, a description written in 1770 reads, "It spread across the sky like a piece of silk cloth and then dispersed" [Chanjipcheong, 1908; Park, 2008]. Applying a power spectrum analysis technique to all sunspot and aurora records during the Goryeo dynasty, Yang et al. [1998] and Lee et al. [2005] have shown 10.5-year and 97-year cycles for the sunspot records and 10-year and 87-year cycles for the aurora records. Copyright 2011 by the American Geophysical Union.