(19) Choson Had Advanced Astronomy

By Yang Sung-jin

U.S.-based director Mimi Leder’s latest film “Deep Impact” is about a doomsday scenario generated by a huge fictional comet which is on a collision course with Earth. Though the movie’s depiction of earth’s inhabitants confronting a comet is far-fetched, moviegoers seem to be going for the concept of an intergalactic vagabond — comet.

Comets were extremely curious objects for the Choson people, as well. There are a total of 1,233 articles related to the subject, “comet,” in the CD-ROM Annals of the Choson Dynasty, a record which suggests there was a high level of interest in astronomy even then.

One record reports that a comet appeared on the evening of Aug. 22, 1660. The Annals describes the incident in detail: “A comet turned up near the Chonchangsung (name of a constellation), and it was a white one, with its tail some two feet long. The comet, which was 32 degrees away from the polestar, disappeared around four kyong (1:00-3:00 a.m.). Meteorological observers were summoned to watch for any further sign of the comet.”

Comets were much more than objects of public curiosity, however, as kings paid close attention to and often took actions based on their movements. For instance, King Sejong ordered officials Lee Sun-ji and Kim Tam to observe the skyline when a comet was spotted on Dec. 22, 1449.

Why were the Choson kings so concerned about comets? Above all, it seems, the comet symbolized the imminent occurrence of natural disasters or human calamities. On Dec. 23, 1449, King Sejong held an emergency meeting with high-ranking officials to discuss the comet in question.

“Now that a comet has been found on the Hyondo and Nangnang tracks of the Heavenly Way, we have to come up with ways to avert the coming disasters. In the past, the Koryo Dynasty left no stone unturned in attempting to prevent any calamities resulting from comets. Even though this comet is not directly related to our nation, we should do something to head off the disasters,” the fourth monarch of the Choson Dynasty said.

Responding to the king’s suggestion, one official said, “As wise men say, people should reconsider their own behavior in light of the impending disaster. At this point, nothing is more important than permitting the people to take a rest while strengthening the army. We don’t have to follow the old practice of the Koryo Dynasty which took generous measures in hopes of preventing disaster.”

King Sejong said, “If there’s nothing to do as far as this matter is concerned, I will do my part anyway by being more careful about my own acts.”

A UFO in Choson?

The case of another comet, spotted on July 22, 1413, is somewhat puzzling. According to an article in the Annals, the comet appeared in the early evening in the northern part of the heavens and circled around for a while before disappearing. Its size was as big as a bowl in the eyes of onlookers, the Annals say.

Intrigued, King Taejong asked the royal astronomer to identify the comet, but even he was not up to the task, as the comet did not fit the description of anything the professional observer had ever seen. This astronomer was later imprisoned for what was viewed as a negligence of duty. Unlikely as it may seem, it may not be wrong to assume that the comet was a UFO which had hovered in the sky over the Choson Kingdom.

Another uninvited and unwelcome guest in the kingdom was the solar eclipse. Since the sun symbolized the power of the king, an eclipse was perceived as heralding a disaster of great magnitude.

Whenever court astronomers predicted a solar eclipse, the king and his officials donned white robes (a symbol of regret and repentance) and held a ceremony aimed at bringing the occurrence of this “unnatural” phenomenon to a close as soon as possible.

On the first day of the year 1422, King Sejong, wearing white royal robes, was seen to beseech the heavens to put a stop to the solar eclipse. Officials followed the king’s example. Eventually, the sun reappeared and the king bowed to the heavens four times in gratitude.

Interestingly, an official named Lee Chon-bong, who predicted that the eclipse would occur 15 minutes earlier than it actually did, was later punished with a cudgeling for his miscalculation.

The solar eclipse which took place on Jan. 1, 1413, provides rare insight into the procedures of the national ceremony designed to neutralize this ominous phenomenon. King Taejong was originally scheduled to take part in a ceremony commemorating New Year’s Day, but having been informed of the impending solar eclipse, he immediately cancelled all of his appointments. Each province then offered horses in observance of a ritual related to solar eclipses. At noon, the king positioned himself on a designated spot in the courtyard and implored the heavens for an end to the eclipse, which ultimately lasted from 12:45 to 15:30.

On this occasion, as well, the royal astronomers miscalculated and predicted that the eclipse would last until 15:45. The 15-minute error was subsequently much disputed in the court.

Life and Death Prediction

“There was a 15-minute difference between the prediction and the actual eclipse. Is the astronomer guilty?” asked the king.

Official Kim Yeo-ji said, “Eclipses happen on a regular basis, therefore the astronomers did make a mistake.”

Official Han Sang-duk argued, “Though it is a regular phenomenon, eclipses never occur at precisely the same time. Perhaps, there might be some problems with the water clock. If this is the case, the astronomers are not guilty.”

Accepting the latter explanation, King Taejong awarded bushels of rice to the astronomers instead of punishing them.

The search report of the CD-ROM Annals shows that during the Choson Dynasty, astronomers recorded the occurrence of 265 solar eclipses and 344 lunar eclipses, which suggests that the astronomy practiced during the Choson Dynasty was relatively advanced.

Nonetheless, astronomers who made mistaken predictions were subject to slapping or imprisonment, suggesting the persistence of rigid and naive notions about eclipses.

King Sejong, however, demonstrated the possession of a practical attitude toward the accuracy of predictions. In mid-1430, the king ordered his officials to predict the dates and times of eclipses more accurately.

“The inaccurate calculations of the occurrences of solar and lunar eclipses and of heavenly movements is due to continued dependence on an outmoded astronomical textbook from China. Therefore, we should base our predictions on the newly published book, which is more accurate, in order to reduce errors,” the king said.

“In addition, record the dates and times of eclipses even when they are not in accord with predictions. In the future, these records can be used for future adjustments of our predictions,” he added.

In 1432, the astronomers predicted an eclipse and yet nothing happened.

Unpredictably, King Sejong did not hurry to punish the astronomers. Instead, he checked whether an eclipse had taken place in any of the provinces and waited for envoys to China to return for further confirmation.

No king was more eager to promote the advancement of science than King Sejong. To promote the practice of astronomy based on accepted scientific methods, King Sejong sent two officials, Kim Han and Kim Cha-an, to China to study advanced mathematics.

Perhaps, if he were alive today, he would be more than willing to watch “Deep Impact.”