Pili

Authors: Boshun YANG

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Pī Lì (Thunderbolt, 霹靂) is a five-star Chinese asterism belonging to the outer asterisms of the Gan school. It lies north of Yunyu (雲雨), south of Leidian (雷電), and is also described as west or south-west of Tugongli (土公吏) and Tugong(土公). Major reconstructions place it near the Circlet of the western fish in modern Pisces.

Concordance, Etymology, History

Pīlì (霹靂) was originally the name of a natural phenomenon. The “Explaining Heaven釋天” section of the Shiming釋名 preserves the variant characters 辟歷 and glosses it as follows: “Pì means ‘to break’; whatever it passes through is broken.” This explanation emphasizes the image of things being shattered wherever the thunderbolt strikes. The Wujing tongyi五經通義 likewise states: “Both zhèn (震) and tíng (霆) are forms of pīlì.” Since zhèn is primarily associated with violent reverberation and impact, while tíng could denote rapid thunder or flashes of lightning in early texts, pīlì was evidently not restricted to thunder as sound. Rather, it could encompass the composite phenomenon of violent thunder, lightning, and the destructive effects of a lightning strike. When a single English equivalent is required, Thunderbolt therefore conveys its semantic range more fully than Thunderclap, which emphasizes sound, or Lightning, which refers primarily to the flash or electrical discharge.

The Kaiyuan zhanjing, juan 70, quotes a verse attributed to the Gan astronomical tradition: “Pīlì surges forth, striking and casting down霹靂奮擊捽.” The Xingjing similarly states that the Pīlì asterism “governs heavenly might and cleaves the myriad things主天威，擘萬物.” Whereas the Léidiàn asterism broadly represents the occurrence of thunder and lightning, Pīlì places greater emphasis on their sudden impact and destructive, rending force, together with the “heavenly might” manifested through such violence.

In later astrological texts, the meaning of the Pīlì asterism was extended from the “heavenly might” displayed in nature to the decrees and legal authority of the sovereign. Astrologers interpreted its brightness, rays, dispersion, clustering, or displacement as indications of how effectively laws and commands were being enforced. Its condition might signify that imperial decrees were excessively harsh, that laws were going unheeded, or even that “the legal order had fallen into decay.” Some prognostications carried this chain of association—from heavenly might to decrees and law—one step further, extending the asterism’s significance to punishment and judicial affairs.

Identification of stars

Star Names or Orders(Qing)	Han Dynasty (SUN X. & J. Kistemaker)	3rd to 6th Century (Boshun Yang)	Song Dynaty (Boshun Yang, 1034 CE)	Song Dynasty (Pan Nai, 1052 CE)	Song Dynasty (Boshun Yang, 1052 CE)	Yuan Dynasty (Pan Nai, 14th century)	Qing Dynaty (Yi Shitong, 18th Century)
1st	β Psc	β Psc	β Psc(determinative）	β Psc(determinative）	β Psc (determinative）	β Psc	β Psc
2nd	γ Psc	b Psc = 7 Psc	b Psc = 7 Psc	b Psc = 7 Psc	γ Psc	γ Psc	γ Psc
3rd	b Psc = 7 Psc	θ Psc	θ Psc	θ Psc	θ Psc	θ Psc	θ Psc
4th	θ Psc	ι Psc	ι Psc	ι Psc	ι Psc	ι Psc	ι Psc
5th	ι Psc	ω Psc （determinative）	ω Psc	ω Psc	ω Psc	ω Psc	ω Psc

Maps (Gallery)

historical map	modern identification	same in Stellarium
Pili, Yunyu and Leidian in Cheonsang Yeolcha Bunyajido	Pili, Yunyu and Leidian before Tang dynasty reconstructed by Boshun Yang	Pili, Yunyu and Leidian before Tang dynasty in Stellarium
Pili, Yunyu and Leidian in Geziyuejintu	Pili, Yunyu and Leidian in Northern Song dynasty(1034) reconstructed by Boshun Yang	Pili, Yunyu and Leidian in Song dynasty(1034) in Stellarium
Pili, Yunyu and Leidian in Suzhou star map	Pili, Yunyu and Leidian in Northern Song dynasty(1052) reconstructed by Boshun Yang	Pili, Yunyu and Leidian in Song dynasty(1052) in Stellarium
Pili, Yunyu and Leidian in Xin yixiang fayao star map	Pili, Yunyu and Leidian in Northern Song dynasty(1052) reconstructed by Pan Nai
	Pili and Yunyu in Yuan dynasty(1360s) reconstructed by Boshun Yang	Pili, Yunyu and Leidian in Yuan dynasty(1360s) in Stellarium
Pili, Yunyu and Leidian in Yixiang kaocheng star map of 18th century	Pili, Yunyu and Leidian in 18th century reconstructed by Yi Shitong	Yunyu of 18th century in Stellarium

IAU Working Group on Star Names

In 2026, the name of the historical constellation "Pili" was suggested to be used for ω Psc in this constellation, for it was used as the earliest determinative star.

Decision: ...

References

References (Chinese)