Pioneer of Modern Astronomy in Korea

In the 18th century, most scholars of the Joseon Dynasty strived to pass the state exam for recruiting public servants. Interestingly, one scholar was observing the sky through a telescope.

The scholar was Hong Dae-yong, a prominent scientist who tried to understand outer space based on geometry and astronomy. The armillary sphere called Honcheonui(혼천의) was designed to indicate the movements of celestial bodies by applying the sophisticated clock mechanism. It is regarded as Hong’s masterpiece. Let’s follow the life of Hong Dae-yong, the Copernicus of Joseon, who triumphed over common sense at the time.

Showing Interest in Science

Hong was born in Suchon(수촌) Village in Cheonwon(천원) County, Chungcheong Province on March 1st, 1731 on the lunar calendar. The Hong clan he belonged to comprised the core of the influential Noron faction that dominated the political scene for generations during the late Joseon period. That is, he was of noble blood that would guarantee his future success.

Despite the family tradition, Hong chose the path of learning. He aspired to learn classical studies when he was ten years old. He entered Seoksil(석실) Confucian School to learn about mathematics and astronomy, while formulating a system of philosophy encompassing Taoism, Buddhism and the teachings of Wang Yangming.

As he grew up, he formed friendships with scholars such as Park Ji-won and Park Je-ga, who were the members of the Northern Learning School advocating practical learning. When his father Hong Yeok(홍역) served as the local minister in Naju in 1759, he met with senior scholar Na Gyeong-jeok(나경적) and began to show interest in astronomy.

Making Honcheonui

At the time, Na was over 70 years old. But Hong was deeply impressed by the elaborate alarm clock made by the old scholar. Together with Na, Hong created another alarm clock and an astronomical observation instrument called Honcheonui.

Unlike the previous Honcheonui, which depended on a waterwheel to move, Hong made his instrument by connecting the mechanical clock with the toothed wheel so the movements of the celestial bodies and their locations could be measured more accurately.

Also, Hong spent his own money in constructing Nongsugak(농수각), which was his private astronomical observatory. He was devoted to observing the heavenly bodies as he believed that the most important element in science was observation and experiments.

Traveling is My Power

Hong’s trip to Beijing invigorated his spirit to explore science. In 1765, he accompanied his uncle Hong Eok(홍억) as his personal secretary on a trip to China and stayed in Beijing for three months. His uncle was one of the members of Joseon’s diplomatic delegation to the Qing Dynasty of China. In Beijing, Hong associated with Qing scholars, such as Yan Cheng and Lu Fei, to accept China’s advanced culture. He also visited a Catholic church frequently to learn about Western modern science through Western missionaries.

Hong’s visit to Beijing had a crucial effect on developing his philosophy. It also led to the publication of his books, and . influenced another travel journal written by renowned scholar Park Ji-won.

is a satirical dialogue between two fictional men who talk about science. One is Silong(실옹) who lives in seclusion in a mountain named Euimuryeonsan(의무련산), and the other is Heoja(허자), a Joseon scholar. Heoja boasts about his education, which he had been cultivating for 30 years. But after meeting Silong, he realizes his knowledge is futile. To readers’ surprise, the book says the Earth rotates once a day to cause day and night. It was the first Asian book to clearly indicate the concept the Earth’s rotation.

Reborn as a Star

Based on traditional natural science of the East, combined with new scientific achievements from the West, Hong maintained the rotation of the Earth and the infinity of outer space. He entered government service for the first time in 1774, when he was 43 years old, to teach King Youngjo’s grandson, who later became King Jeongjo. He also assumed several public posts, including local county governor, before he died in 1783. He was 53.

Lamenting over Hong’s death, his friend Park Ji-won wrote, “Hong Dae-yong had a profound insight and was considerate and full of creative wits. He was a true scholar of practical learning who synthesized and analyzed things systematically.”

Hong was a true scientist who presented his logical ideas through his lifelong dedication to nature and research. In 2005, Korean scientists discovered an asteroid shining in space between the orbits of Mars and Jupiter. They named it Hong Dae-yong. With the shining star, his name will be remembered forever.