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Reading the Heavens Part 1 – Two Millennia of Astronomy in Korea

To celebrate star-crossed lovers everywhere, Matthew Jackson starts a series of articles on Korean astronomy

As we can tell from ancient monuments like the Dolmen stones and more recent buildings such as Cheomseongdae, astronomy was big in Korea. Why was this exactly?

Reverence for nature was part of it, but it was in fact more specific than that, and resembles what today might appear to us to be more akin to astrology than science. Here is an extract from the History of Koryo, which explains why it is important to observe the movements of the stars:

With signs thus expressed, the Heavens show fortune and misfortune,
And the wise will give heed to what they show.

The belief expressed here is that the Heavens are like a mirror reflecting the human world, and they reveal good and evil through events and transformations in the celestial world. Therefore, the wise always pay attention to the Heavens as the world’s reflection, and try to understand its meaning and follow its will.

Astronomy reached its zenith under King Sejong in the 15th century, but the history of classical Korean astronomy spans over two millennia, totally some 20,000 individual records. Observations need to be taken over long periods to discern patterns and movements.

These observations cover solar eclipses, eclipses of planets by the moon, planetary movements, comets, changes in the brightness of planets, meteors, meteorites and meteoric showers, auroras, and rare appearances of southern stars.

Astronomy graphic

The sun has only been regularly observed with telescopes for the past 300 years. While Galileo began his observations in 1611, China and Korea already had amassed hundreds of years of data. Korean records, for example, reveal an 11-year cycle in solar activity. It was not until 1843 that German astronomer Samuel Schwabe established this principle in western astronomical science.

The observation and documentation of comets in Korea was also conducted over a long period of time. ‘Halley’s Comet’, identified by Edmond Halley in 1705, was recorded consistently in Korean records from 989 to 1835, and in great detail, including information about color, size, tail length and even the officials who observed it.

We can also observe how meteor showers changed over time from the first millennium AD to the second. According to records, the largest number of falling stars could be seen on the twenty-fifth day of the seventh month.

Modern software allows us to extrapolate solar and stellar movement back in time. Compared with this data, the accuracy of records of solar eclipse in Korea is high (79%) compared with China (~70%), and Japan (35%). The History of the Three Kingdoms from Korea is therefore the most credible amongst ancient astronomical sources.1

Dates Period Astronomical Heritage
30th Century BCE – 2nd Century CE Stone, Bronze & Iron Age
  • Petroglyphs, constellations of dolmens, menhirs and burial items
24th Century BCE – 2nd Century BCE Old Joseon
  • 12 Astronomical records
  • Chamsongdam Observatory at Mt Manisan, Kanghwa-do
57 BCE – 935 CE
37 BCE – 668 CE
18 BCE – 660 CE
  • Over 240 Astronomical records in History of the Three Kingdoms and Memorabilia of the Three Kingdoms
  • 25 Koguryo tomb murals depicting star maps
  • Chomsongdae observatory in Gyeongju established (observatory survives to this day)
  • Sundials, statues of four-directional animals2, 12 zodiacal animal deities.
918 – 1392 CE Koryo
  • Over 5,000 astronomical records in History of Koryo
  • Chonsongdang observatory in Kaesong
  • 9 Koryo tomb murals depicting star maps
1392 – 1910 CE Joseon
  • Over 15,000 astronomical records in the Royal Annals of the Joseon Dynasty, Diaries of the Royal Secretariat, and Daily Records of the Stars
  • Astronomical installations, eg observatories, armillary spheres and celestial globes
  • Astronomical literature, charts
  • Timekeeping devices such as sundials, clepsydrae (water clocks) and astronomical clocks
  1. A more detailed discussion of this study may be found in the research papers of Park Changbom and La Daile. Park Changbom, La Daile, “Verification of the Independence of the Astronomical Observations in the time of Three Kingdoms”, Journal of the Korean History of Science Society, Vol.16 (1994). []
  2. The four mythical animals in East Asian tradition that represent the four points of the compass: Blue dragon (East), White tiger (West), Red phoenix (South), and half-turtle, half-serpent (North)  []

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