Science1442

Chiljeongsan calendar compiled

Yi Sun-ji, Kim Dam and others completed the Chiljeongsan, a calendar computing the motions of the sun, moon and five planets for the meridian of Hanyang.

First page of the Veritable Records of Sejong, which carry the Chiljeongsan treatises in their final volumes
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“Chiljeong” means the seven heavenly bodies: sun, moon, Mercury, Venus, Mars, Jupiter and Saturn. The inner volume drew on the Yuan Shoushi and Ming Datong calendars, the outer on the Islamic (Huihui) calendar. It was the first Korean calendar to compute celestial motion for Hanyang instead of borrowing Chinese tables.

Sejong’s reign also produced the armillary sphere and simplified armilla, the bowl-shaped sundial angbu ilgu, the self-striking water clock and the rain gauge, and cast the Gabin movable metal type (1434).

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States and rulers at the time: Joseon — Sejong

People

Sejong the Great1397 – 1450
monarch · Fourth king of Joseon, creator of Hangul, patron of science and of the northern frontier

Before and after

Earlier: 1441 Rain gauge
Later: 1443 Gyehae Treaty

Themes that include this event

Turkic-Islamic Empires and Other Civilizations1000 – 1533
From the Ghaznavid raids on India to the Mughal Empire and Suleiman I — five centuries in which Turkic-led Islamic empires took western Asia and India, while Africa, Southeast Asia and the Americas raised civilisations of their own
Science and Technology HeritageAD 633 – 1861
From Cheomseongdae to the Daedong yeojido — instruments and maps that measured the sky, kept time, gauged rain and charted the land