Origin 433 BCE
The twelfth mansion lies across Aquarius and Pegasus. It carries themes of height, roofs, walls and danger, and governs building work and matters requiring caution. Three of the twenty-eight lodges share the romanised form Wei while being written with different characters and lying in different quarters of the sky, and two share the form Bi. The collisions are created by romanisation and do not exist in the Chinese script, but they are a persistent source of confusion in English-language accounts of the system.
Facts
Identity
Equatorial Extent (Du)17 du (about 16.8 degrees of equatorial arc) 2Tradition: Han-era Shi Shen tradition (Kaiyuan Zhanjing) Du: the arc-degree unit of the classical Chinese calendar, where a full circle equalled 365 and a quarter du (about 0.9856 modern degrees per du). This width is the Han-era figure standardized under the Taichu calendar and preserved in the Tang-dynasty Kaiyuan Zhanjing's Shi Shen star table; later dynasties recorded small revisions as precession shifted the determinative stars, so this is one epoch's figure, not a timeless constant. It measures the mansion's extent along the celestial equator (right ascension), the coordinate system Chinese astronomy actually used, not a position on the ecliptic (tropical zodiac); the atlas has no sourced mapping from this equatorial system onto a start point in ecliptic longitude, so this figure alone cannot be substituted into a start-end boundary range the way the equal Arabic-mansion spans are. Determinative StarAlpha Aquarii 2Tradition: Han-era Shi Shen tradition (Kaiyuan Zhanjing) Origins
Origin Period433 BCE 1Tradition: Chinese equatorial astronomy Origin PeriodThe full set of twenty-eight lunar mansions is attested together for the first time on the lacquer box from the tomb of Marquis Yi of Zeng, sealed in 433 BCE, the earliest surviving object to record the complete list of names. 1 Origin of the NameThe English "lunar mansion" is borrowed from the Indian nakshatras and the Arabic manazil and misdescribes the xiu. A xiu is a lodge marked by a determinative star and measured in right ascension along the celestial EQUATOR; it is not a division of the Moon's ecliptic path, and the three systems are not variants of one scheme. 2 Attributions
PalaceBlack Tortoise of the North 1 Learn More
The Lunar Mansion Wei (Rooftop)
Wei (Rooftop) is the twelfth of the twenty-eight xiu, the lunar mansions of traditional Chinese astronomy. Each xiu is a segment of the sky marked by a group of stars near the celestial equator, and together they divide the heavens into the belt through which the sun, moon and planets appear to move.
Palace, animal and place in the sky
This mansion belongs to the Black Tortoise of the North, the quadrant of the sky lying toward the north, one of the four symbolic creatures among which the twenty-eight are shared out seven to each. In the later scheme that pairs every mansion with a creature, Wei is assigned the Swallow.
The twenty-eight mansions are among the oldest elements of Chinese sky-lore, attested well before the common era and used to track the nightly progress of the moon and to fix the calendar. The system is described here as that documented astronomical and calendrical tradition, from which its astrological uses later grew.
Wei, the Rooftop of the Black Tortoise
Wei, the Rooftop, is the twelfth of the twenty-eight xiu and the fifth mansion of the northern palace, the Black Tortoise, one of two mansions romanised Wei, this one meaning rooftop or ridgepole. It is identified with stars in Aquarius and Pegasus. In the later astrological tradition its animal totem is the Swallow. As one of the twenty-eight lunar mansions it tracks a segment of the Moon's monthly path. These are the conventions of the Chinese astronomical and calendrical tradition, in which the twenty-eight xiu order the heavens into four palaces of seven mansions each; the Black Tortoise of the north, from Dipper to Wall, gathers the mansions the almanac assigns to the winter quarter of the year.
Wei the Rooftop is one of three separate mansions romanised identically as Wei in the Latin alphabet despite representing three unrelated Chinese characters and meanings, tail, rooftop and stomach; the repetition is purely an accident of romanisation systems that do not mark tone or preserve the original character, and readers working from English-language sources should not assume any connection between the three simply because the transliterated spelling coincides rather than the underlying Chinese writing.
Cross-Tradition Connections
Contained In
One of the seven lunar lodges of this palace.
Originates in Language
Sources
1. Astrology and Cosmology in Early China: Conforming Earth to Heaven
David W. Pankenier, Cambridge University Press, 2013On the twenty-eight lodges and the Zeng Hou Yi lacquer chest
2. Science and Civilisation in China, Volume 3: Mathematics and the Sciences of the Heavens and the Earth
Joseph Needham, Cambridge University Press, 1959Vol. 3, the section on astronomy: the hsiu (lunar mansions), the equatorial system and the du measureQuote, Vol. 3, the section on astronomy: the hsiu (lunar mansions), the equatorial system and the du measure
The twenty-eight lodges are equatorial divisions bounded by determinative stars and so of unequal width, measured in du on a circle of 365.25 parts; their relation to the Indian and Arabic lunar mansion systems is unresolved.
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