Waiping

Authors: Lyu Haocheng

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Waiping in Stellarium

Waiping (外屏)

Asterism Info
Native	外屏
Romanisation	Wài Píng
IPA	/waɪ˥˩.pʰiŋ˧˥/
Translation	Outer Fence
Position (2000)
Right ascension	12.175 to 30.514375
Declination	2.7654444 to 7.8916944
Area	0 sq. deg.
Stars
Bright stars	7
Bayer/Flamsteed stars	7
Stars brighter than 3.00m	0
Brightest star	α Psc (3.82m)
Taxonomy
category of asterism	constellation
IAU- constellations	Psc

Wài Píng (外屏, Outer Fence) is a traditional Chinese asterism belonging to the Kui (奎) mansion. Among the Three Schools of ancient Chinese astronomy, it is classified as a Gan School asterism (甘氏星). The asterism consists of seven stars located south of Kui (奎). In modern constellation boundaries, Waiping lies within Pisces.

Concordance, Etymology, History

The name "Wài Píng" literally means "Outer Fence" or "Outer Screen" — a barrier on the outside. The seven stars of Waiping are positioned south of Kui (奎) to shield and block foul odours. The Gan Shi Zan (甘氏讚 / Gan's Eulogy) states:

"The fence encloses and conceals; the pigsty remains unseen."

The establishment of Waiping is closely connected with Tianhun (天溷, Celestial Pigsty) to its south. The character hùn (溷) carries a dual meaning, referring to both a pigsty and a latrine — a building complex where the latrine was attached to the pigsty. Tianhun lies south of Waiping, and the function of Waiping is precisely to block the foul odours emanating from Tianhun. The Tang dynasty poet Li Bo (李播), in his Tianwen Daxiang Fu (天文大象賦 / Rhapsody on the Great Images of the Celestial Sphere), writes:

"The circular granary (Tianqun, 天囷) and the square granary (Tiancang, 天倉) are established for storing and gathering; the pigsty (Tianhun, 天溷) and the fence are erected in overlapping layers." (立囷倉之儲聚，樹溷屏之重復。)

Here, "pigsty" and "fence" refer to Tianhun and Waiping respectively, while "overlapping layers" describes the layering of screens — barrier upon barrier — erected to block and conceal foul odours.

Naming and Etymology

The Chinese character píng (屏) can mean a fence, screen wall, or folding screen. As a Gan School asterism, the name "Outer Fence" (外屏, Wàipíng) stands in clear opposition to the Inner Screen (內屏, Nèipíng) of the Shi School. In the Chinese asterism system, there are three "screen"-related asterisms: the Shi School's Inner Screen and Screen (屏, Píng), and the Gan School's Outer Fence. The Inner Screen is located inside the main gate (端門, Duānmén) of the Supreme Palace Enclosure (太微垣, Tàiwēi Yuán), serving to shield the Celestial Court so that the Emperor's Seat within cannot be seen directly from outside. Another Screen asterism is placed in front of the Toilet asterism (廁, Cè), also for the purpose of shielding. The Outer Fence, though belonging to the Gan School rather than the Shi School, serves a similar function: to shield the Celestial Pigsty (Tianhun) to its south from view.

History

The use of a píng (屏, screen wall) to enclose a latrine is already attested in pre-Qin texts. The Mozi (墨子), in the chapter "Flags" (Qízhì, 旗幟), records:

"Outside the roadway a screen wall (屏, píng) should be built; thirty paces beyond it a circular enclosure (圜, yuán) is to be constructed, one zhang in height. This is to serve as the people's latrine (圂, hùn), with walls no less than twelve chi high."

Here, píng refers to a screen wall used to enclose the latrine, while hùn (圂/溷) was another ancient designation for a toilet. This matches exactly the celestial arrangement of the Outer Fence shielding the Celestial Pigsty.

Identification of stars

The identification of the seven stars of Waiping is well established. The determinative star is the westernmost star, identified as δ Psc.

Star Names or Orders(Qing)	Han Dynasty (SUN X. & J. Kistemaker)	before Tang dynasty: 3rd to 6th Century (Boshun Yang)	Song Dynaty: Jingyou, 1034 (Boshun Yang)	Song Dynaty: Huangyou, 1052 (Pan Nai, based on Xinyixiangfayao Star Map)	Yuan dynasty: 1279-1368 (Pan Nai)	Qing dynasty: 18th Century (Yi Shitong)	Ho PENG YOKE
1st (Determinative)	δ Psc	δ Psc	δ Psc	δ Psc	δ Psc	δ Psc	δ Psc
2nd	ε Psc	ε Psc	ε Psc	ε Psc	ε Psc	ε Psc	ε Psc
3rd	ζ Psc	ζ Psc	ζ Psc	ζ Psc	ζ Psc	ζ Psc	ζ Psc
4th	μ Psc	μ Psc	μ Psc	μ Psc	μ Psc	μ Psc	μ Psc
5th	ν Psc	ν Psc	ν Psc	ν Psc	ν Psc	ν Psc	ν Psc
6th	ξ Psc	ξ Psc	ξ Psc	ξ Psc	ξ Psc	ξ Psc	ξ Psc
7th	α Psc	α Psc	α Psc	α Psc	α Psc	α Psc	α Psc

Maps (Gallery)

Historical Maps
Waiping on Cheonsang Yeolcha Bunyajido	Waiping on Suzhou Star Map	Waiping on Yixiang Kaocheng star map (18th century)

IAU Working Group on Star Names

In 2026, the name of the historical constellation "Waiping" was suggested to be used for one of the stars in this constellation. Since δ Psc is the determinative star of it, then this name should be applied to δ Psc.

Decision: ...

References

References (Chinese)