From time immemorial people have observed the heavens and the motions of celestial bodies, and recorded stars and constellations. In Korea, the people of the ancient Goguryeo Kingdom left behind tomb murals depicting various stars and asterisms that embodied their astronomical knowledge. Star maps provided the basic guidance in astronomical observation.

Interpreting Human Affairs through Events in the Sky
In traditional Korean astronomy, the heavens were regarded as reflections of the human world. The celestial sphere was divided into 28 lunar mansions in three schools, whereas traditional Western astronomy was based on 12 constellations straddling along the ecliptic. The stars and star groups were named after kings, palaces, markets, and familiar figures like the Herdsman (Altair) and the Weaver (Vega), or the Seven Stars of the Northern Dipper (Big Dipper). Our ancestors believed that the heaven, earth and humans were organically interrelated, so they sought to interpret human affairs by carefully observing unexpected events taking place in the celestial world.

As stars were regarded as intermediaries between heaven and man, they were used as important clues in reading the will of heaven as well as predicting the fate of humans. Particularly, the kings of succeeding dynasties utilized constellations in governance as they believed that changes in the heavens were related to the fortunes of their kingdom.

Production of Planisphere Chart
Yi Seong-gye, or the Taejo who founded the Joseon Dynasty in 1392, needed a medium to prove that he had established a new dynasty with the mandate of heaven in order to consolidate its legitimacy and heighten pride as a strong and lawful monarchy. Fortunately, at that time, a rubbed copy

of a stone-carved astronomical chart was delivered to him; the stone carving made in Goguryeo (37 B.C.-A.D. 668) was known to have been submerged in the Taedong River and lost during the war that led to the fall of the ancient kingdom.

Taejo ordered court astronomers, including Gwon Geun and Yu Bangtaek, to produce a new astronomical chart by supplementing the ancient version. Eleven scholars at the court office for astronomical observation, Seoungwan, observed stars to eliminate the errors arising over seven centuries; the result was a far more detailed and precise chart containing not only the names of stars and constellations but rich astronomical information. This new chart, completed in 1395 and named “Cheonsang yeolcha bunya jido,” meaning a “planisphere chart of different celestial zones,” is now Korea’s National Treasure No. 228. It is the second oldest stone-carved astronomical chart in the world.

1,467 Stars Form 283 Constellations
This 14th-century planisphere chart, 122 centimeters wide and 221 centimeters long, divides the celestial sphere into 12 zones. It presents a total of 1,467 stars forming 283 constellations; the stars are depicted in different sizes to represent different degrees of brightness. The chart has more than three times as many constellations than Western astronomical charts produced during the similar period, which have 88 constellations.

The outermost circle measures 76 centimeters in diameter and has the North Star at the center along with the sun’s ecliptic and the equator equidistant from the North Pole and South Pole. The chart delineates the paths of movement of the five visible planets (Mercury, Venus, Saturn, Mars and Jupiter) and subsequent seasonal divisions. The Joseon astronomers precisely recreated the night sky observed by people of Goguryeo with incredible knowledge and expertise.

Rediscovery of the Planisphere Chart
The whereabouts of the astronomical charts remained unknown until the 1960s, when the original stone carving was found abandoned on the grounds of Changgyeong Palace which was turned into a zoological park during the colonial period. A family needing a table for their picnic there happened to find a stone block under the eaves of the Myeongjeongjeon pavilion. While covering the stone with cloth to place their food on it, the family noticed the rectangular block was carved with strange patterns of numerous small dots. Thus the priceless astronomical relic was brought to light after being discarded in grass to be trampled under countless feet over a half century.

A folding screen with “old and new” astronomical charts from the East and the West, respectively, designated Treasure No. 1318.