Collected Illustrations of the Three Realms, Volume 4: Astronomy

Page 6

Diagram of the Sun’s Middle Path

This diagram from the Sancai Tuhui (c. 1609) illustrates the "Middle Path of the Sun," representing the celestial sphere and the sun's trajectory during the Summer Solstice. The outer circle features the Twelve Earthly Branches (Zodiac signs), while the interior text provides astronomical measurements and cosmological descriptions.

Wu The seventh Earthly Branch, representing the direction of South and the time of Noon; traditionally placed at the top of Chinese maps The Center of Heaven; the North Pole 59.5 Degrees Summer Solstice The Path of the Sun; reaching its highest point in the center of the heavens. Heaven surrounds the exterior of the Earth; the Earth resides in the center. That part of Heaven visible from the Earth is 182.5 degrees and a fraction In ancient Chinese astronomy, a "degree" (du) represented the distance the sun travels in one day, totaling 365.25 degrees for a full circle; that which passes beneath the Earth is also 182.5 degrees and a fraction. The Celestial Axis Tianshu: The pivot or axis on which the heavens were thought to rotate consists of the North and South Poles; this means the North and South Poles support the two ends [of the axis]. The Great Void, along with the sun, moon, and the Stars and Mansions Xingxiu: The stars and the 28 lunar mansions of the Chinese constellation system, rotates obliquely. Zi The first Earthly Branch, representing the direction of North and the time of Midnight The Center of Heaven; the North Pole Wei South-Southwest: Distance from the Central Pole... Shen West-Southwest: Distance from the Central Pole is 24 degrees; Distance from... is 31 degrees. You West Xu West-Northwest Hai North-Northwest Chou North-Northeast Yin East-Northeast: Distance from the Central Pole... Mao East Chen East-Southeast Si South-Southeast

The diagram visualizes the "Gaitian" (Covering Heavens) or "Huntian" (Celestial Sphere) theories, where the earth is a central hub and the celestial bodies rotate around an inclined axis. The measurements provided (such as the 59.5 degrees) are specific to the observational latitude of the Ming dynasty capital, likely Beijing, at the time of the solstice.