Moon crater honors Joseon-era astronomer

A graphic highlights the location of the Nam Byeong-Cheol crater on the moon's surface. (Kyung Hee University)

In a groundbreaking moment for Korean astronomy, the International Astronomical Union has named a lunar crater after 19th-century Joseon-era polymath Nam Byeong-cheol, marking the first time a Korean name has been assigned to a feature on the moon's surface.

The Danuri Magnetic Field Payload Research Team from the Department of Space Exploration at Kyung Hee University said Monday that a crater on the far side of the moon, discovered through international collaborative research, has been named after Nam Byeong-cheol (1817-1863), a Joseon-era astronomer and mathematician. To date, 1,659 craters have been officially named.

Even to many Koreans, Nam is a relatively unknown figure, often referred to by local media only as a “distinguished late Joseon-era astronomer.” However, this description merely scratches the surface of his illustrious career. Nam was not just an astronomer; he excelled as a statesman, scientist and scholar, leaving behind a legacy of significant achievements.

Among his most notable contributions is the “Nam Byeong-cheol armillary sphere.” An armillary sphere is an astronomical device used to model the movements and measure the positions of celestial bodies. Nam’s version of the device was an improved design that made celestial observations more accessible and accurate.

In 1859, he authored a scientific encyclopedia detailing the astronomical instruments of the day, including early forms of terrestrial globes and armillary spheres. His instructions were so precise that earlier this year, the Korea Astronomy and Space Science Institute successfully reconstructed an armillary sphere based on his writings.

His 1861 book, "Haekyongsechohae," delved into Euclidean geometry, featuring diagrams and formulas for calculating various sides and angles within right triangles, as well as methods for solving quadratic equations.

The following year, Nam's inquiry extended to theoretical considerations in astronomy and physics. His 1862 work, "Chubosokhae," marked a milestone in Joseon-era astronomy, charting planetary orbits and proposing novel timekeeping methods. The work explains calculation methods for the sun, moon, lunar and solar eclipses, as well as the movement of the stars, using Kepler's elliptical orbital theory and concepts from Italo-French astronomer Cassini.

Nam’s contributions to the natural sciences were not isolated from his political life. Nam closely associated with reformist politicians of the era who pushed for embracing Western knowledge of the day to develop commerce and technology, challenging the more conservative, isolationist streak of the establishment. His close ties with members of the Silhak school and his passion for astronomy and mathematics set him apart from late Joseon's Confucian scholars, who increasingly favored formalism and metaphysical debates over more practical, realistic and experimental pursuits.

Nam racked up an impressive roster of high-profile positions over his three-decade career in public service. He twice held ministerial positions akin to today's foreign, education and interior ministers. He also headed one of the Joseon kingdom's most prestigious offices, the Gwansanggam, which was in charge of astronomy, geography, calendars, meteorology, celestial divination and managing water clocks.

By Moon Ki-hoon(moonkihoon@heraldcorp.com)