View source for Tianyue

{{DISPLAYTITLE: Tianyue (天籥)}} 

{{distinguish|}}

Authors: {{PAGEAUTHORS}}
----
[[File:Tianyue in Stellarium.png|alt=Tianyue in Stellarium|thumb|Tianyue in Stellarium]]
{{Infobox constellation
| name = Tianyue (天籥)
| native = 天籥
| translation = Celestial Keyhole
| pronounce = Tiān Yuè
| IPA = /tʰjɛn˥.ɥɛ˥˩/
| culture = Chinese
| RA = ... to ...
| dec = ... to ...
| areatotal = xx.xx
| numbermainstars = 8
| numberbfstars = 4
| numberstarsplanets =
| numberbrightstars = 0
| numbernearbystars =
| brighteststarname = HIP 88839
| starmagnitude = 4.56
| neareststarname =
| stardistance =
| numbermessierobjects =
| meteorshowers =
| bordering = Sgr
| notes =
| cat = constellation
}}

Tiān Yuè (天籥, Celestial Keyhole) is a Chinese constellation belonging to the [[Nandou|''Dou'' (Dipper)]] lunar mansion. Among the Three Schools of ancient Chinese astronomy, it is classified as a Wu Xian asterism. The asterism consists of 8 stars located west of the second star in the handle of the Southern Dipper ([[Kaus Borealis|λ Sgr]]), at the border between [[Sagittarius]] and [[Ophiuchus]]. 

== Concordance, Etymology, History ==

=== Name and Symbolism ===
The character 籥 (yuè) is the original form of 钥 (yào), meaning a lock or key. Tian Yue is also written as Tian Yao (天钥), both meaning "the celestial lock and key". The ancients believed that this asterism governed the functions of opening and closing, hence its name.

=== Astronomical Position and Historical Significance ===
The placement of Tian Yue is closely connected to the Southern Dipper (''[[Nandou]]''). The Southern Dipper is one of the Twenty-Eight Mansions, which are distributed along the ecliptic—the path traversed by the Sun, Moon, and Five Planets. The Southern Dipper lies precisely at the intersection of the ecliptic and the Milky Way, granting it a special status in the celestial system.

This region lies within the Milky Way, and asterisms located in the Milky Way were often conceived as ferries or fords (for example, [[Tianjin]], the Celestial Ford). Tian Yue is situated in a region called "Ximu zhi Jin" (析木之津, "the Ford of Ximu"). Ximu is one of the Twelve ''Xingci'' (十二星次 / Twelve Divisions), a Chinese system of dividing the celestial sphere into twelve segments by right ascension, based on Jupiter's orbital period (approximately 12 years) rather than on fixed asterisms like the Western zodiac. The ''Erya, Shitian'' (尔雅·释天 / ''Erya'': Explanation of Heaven) records:<blockquote>"The Ford of Ximu (析木之津) is Hanjin (汉津) between Ji (箕, Winnowing Basket) and [[Nandou|Dou]] (斗, Southern Dipper)."</blockquote>Here, "Hanjin" refers to the ford of the Milky Way. The ''Guoyu'' (国语 / ''Discourses of the States'') records the celestial omens at the time of King Wu's conquest of the Shang dynasty around 1046 BCE:<blockquote>"Jupiter was at Chunhuo (鹑火, approaching the constellations of [[Hydra]] and [[Leo]]), the Moon was at [[Fang|Tiansi]] (天驷, the Room mansion), and the Sun was at the Ford of Ximu."</blockquote>This demonstrates the great importance ancient China attached to this region—the passage of the Sun, Moon, and planets through this area was often used to mark significant historical events.

=== Function and Symbolism ===
Because of the special significance of the Southern Dipper's position, the ancients regarded it as "Tian zhi Duguan" (天之都关, "the metropolitan pass of Heaven")—a celestial gateway through which the Sun, Moon, and Five Planets had to pass. Tian Yue was the key that controlled the opening and closing of this gate. In the night sky, the asterisms of [[Nandou]] (Southern Dipper), Tian Yue, [[Jian]] (Establishment), and Gou (Dog) together form the complete image of a celestial pass.

It is worth noting that the Milky Way and the ecliptic intersect at two points on the celestial sphere: one is located near Tian Yue, and the other is at Dongjing (东井, the Well mansion). On that opposite side, Dongjing, together with [[Tianguan]] (Celestial Pass), Nanhe (Southern River) and Beihe (Northern River), likewise forms a pass-like asterism configuration.

=== Identification of stars ===
{| class="wikitable"
|+
!Star Names or Orders(Traditional/Qing)
!style="color: gray;" |Ho PENG YOKE<ref>P.-Y. Ho, “Ancient And Mediaeval Observations of Comets and Novae in Chinese Sources,” ''Vistas in Astronomy'', 5(1962), 127-225.</ref>
!style="color: gray;" |Yi Shitong<ref>Yi Shitong伊世同. ''Zhongxi Duizhao Hengxing Tubiao''中西对照恒星图表1950. Beijing: Science Press.1981.</ref>
Based on catalogue in 18th century
!style="color: gray;" |Pan Nai<ref name=":0">Pan Nai潘鼐. ''Zhongguo Hengxing Guance shi''中国恒星观测史[M]. Shanghai: Xuelin Pree. 1989. Fig 55.</ref>
based on Xinyixiangfayao Star Map
!Boshun Yang<ref name=":1">B.-S. Yang杨伯顺, ''Zhongguo Chuantong Hengxing Guance Jingdu ji Xingguan Yanbian Yanjiu'' 中国传统恒星观测精度及星官演变研究 (A Research on the Accuracy of Chinese Traditional Star Observation and the Evolution of Constellations), PhD thesis, (Hefei: University of Science and Technology of China, 2023). 235-296.</ref>
before Tang dynasty
!Boshun Yang<ref name=":1" />
Song Jingyou(1034)
|-
| 1st
| style="color: gray;" | 63 Oph (HIP 87706)
|style="color: gray;" | 63 Oph (HIP 87706)
|style="color: gray;" | 4 Sgr (Determinative)
| 4 Sgr (Determinative)
|  7 Sgr 
|-
| 2nd
|style="color: gray;" | HIP 87099
|style="color: gray;" | -
|style="color: gray;" | 1 Sgr
| 1 Sgr
| 1 Sgr (Determinative)
|-
| 3rd
|style="color: gray;" | 58 Oph
|style="color: gray;" | 58 Oph
|style="color: gray;" | 70 Sgr
| 70 Sgr
| 70 Sgr
|-
|4th
|style="color: gray;" | -
|style="color: gray;" | HIP 86352
|style="color: gray;" | HIP 89678
| HIP 89678
| HIP 89678
|-
|5th
|style="color: gray;" | 52 Oph
|style="color: gray;" | 52 Oph
|style="color: gray;" | HIP 88839
| HIP 88839
| HIP 88839
|-
|6th
|style="color: gray;" | 51 Oph
|style="color: gray;" | 51 Oph
|style="color: gray;" | HIP 88012
| HIP 88012
| HIP 88012
|-
|7th
|style="color: gray;" | HIP 85783
|style="color: gray;" | HIP 85783
|style="color: gray;" | HIP 87836
| HIP 87836
| HIP 87836
|-
|8th
|style="color: gray;" | 3 Sgr
|style="color: gray;" | 3 Sgr
|style="color: gray;" | 63 Oph (HIP 87706)
| 63 Oph (HIP 87706)
| 63 Oph (HIP 87706)
|}

=== Maps (Gallery) ===
{| class="wikitable"
|+
!historical map
!modern identification
(Yang 2023)
!same in Stellarium 24.4
|-
|[[File:Tianyue in Cheonsang Yeolcha Bunyajido.png|alt=Tianyue in Cheonsang Yeolcha Bunyajido|thumb|Tianyue in ''Cheonsang Yeolcha Bunyajido'']]
|[[File:Tianyue before Tang Dynasty reconstructed by Boshun Yang (2023).png|alt=Tianyue before Tang Dynasty reconstructed by Boshun Yang (2023)|thumb|Tianyue before Tang Dynasty reconstructed by Boshun Yang (2023)]]
| rowspan="2" |[[File:Tianyue in Stellarium.png|alt=Tianyue in Stellarium|thumb|Gouguo before Qing Dynasty in Stellarium]]
|-
|[[File:Tianyue in Suzhou Star Map.png|alt=Tianyue in Suzhou Star Map|thumb|Tianyue in Suzhou Star Map]]
|[[File:Tianyue in Song Dynasty (Huangyou period) reconstructed by Pan Nai (2009).png|alt=Tianyue in Song Dynasty (Huangyou period) reconstructed by Pan Nai (2009)|thumb|Tianyue in Song Dynasty (Huangyou period) reconstructed by Pan Nai (2009)]]
|-
|[[File:Tianyue in Yixiang Kaocheng Stat Map (18th century).png|alt=Tianyue in Yixiang Kaocheng Stat Map (18th century)|thumb|Tianyue in ''Yixiang Kaocheng'' Stat Map (18th century)]]
|[[File:Tianyue in Qing dynasty reconstructed by YI Shitong based on Yixiang Kaocheng Star Catalogue (18th century).png|alt=Tianyue in Qing dynasty reconstructed by YI Shitong based on Yixiang Kaocheng Star Catalogue (18th century)|thumb|Tianyue in Qing dynasty reconstructed by YI Shitong based on ''Yixiang Kaocheng'' Star Catalogue (18th century)]]
|[[File:Tianyue in Qing dynasty (18th century) in Stellarium..png|alt=Tianyue in Qing dynasty (18th century) in Stellarium.|thumb|Tianyue in Qing dynasty (18th century) in Stellarium.]]
|}


== IAU Working Group on Star Names ==
In 2026, the name of the historical constellation "Tianyue" was suggested to be used for one of the stars in this constellation. The star 4 Sgr was recommended, as it is the historical determinative star of the asterism and lies closest to the intersection of the ecliptic and the Milky Way, aligning well with the asterism's symbolic meaning.

Decision: ... 

==References ==
[[References (Chinese)]]


[[Category:Asterism ]][[Category:Constellation ]]
[[Category:Eurasia]][[Category:Asian]][[Category:East Asian]]
[[Category:Chinese ]]
[[Category: Sgr]]