二十八宿 Basic sense: twenty-eight constellation

Indian nakṣatra or Chinese xiu 宿.

In Vedic times nakṣatra originally just meant star and later came to refer to constellations constituting lunar stations along the ecliptic 周天.

A complete list of twenty-eight nakṣatra-s is first provided in the Atharvaveda.

The Vedic literature does not provide accurate coordinates and later Indian star catalogs are inconsistent with respect to the yogatārā-s (the principal star of a nakṣatra), making comparisons with the Chinese xiu problematic. The origins and reasoning behind the Sanskrit names are also largely unclear aside from those named after their shape (Mṛgaśīrṣa = deer's

head), which has led to suggestions they are not of Indian origin. The Chinese likewise developed a model of twenty-eight lunar stations, which was complete by the mid-fourth century BCE, having developed in the preceding centuries. This has led to modern speculation of them having a common –

presumably Babylonian – origin or one culture having first developed the system before transferring it abroad, though the issue remains contentious. Translators in China were able to use the existing Chinese terms when translating Indian texts, though it was recognized only a few of the stars mutually correspond (see Kakushō's 覺勝 edition of the Xiuyao jing 宿曜經; Wakita 脇田, 1897).

In earlier Sanskrit works the list commences from Kṛttikā and later it is from Aśvinī, a change attributed to precession of the equinoxes. Indian astronomical models can exclude Abhijit 牛宿 and work exclusively with twenty-seven nakṣatra-s 二十七宿.

The Chinese system does not allow for this. Generally in the 27 model each nakṣatra can occupy equal space, whereas in the 28 model the distances vary, and are measured by muhūrta (the time it takes

the moon to pass through its space, see 三十時). Alternatively, Abhijit can be recognized yet subsumed under Uttarāṣāḍhā or Śravaṇa, as in the Mātaṅgī-sūtra 摩登伽經 (T 1300) (月在牛宿如斗星說).

The number 27 divides into whole numbers such as with the ecliptic being divided into 108 pāda-s or quarters 足, where each nakṣatra can be evenly assigned 4 pāda-s (108 ÷ 27 = 4). The twelve zodiacs 十二宮, which were originally introduced to India from Babylonian

and Hellenistic sources, are each assigned 9 pāda-s of the ecliptic (108 ÷ 12 = 9).

The 9 pāda-s of a zodiac are divided among 3 nakṣatra-s which they are associated with. For example, Leo 師子宮 has the following assignments according to the Xiuyao jing:

Maghā: 4 pāda-s. Pūrvaphālgunī: 4 pāda-s. Uttaraphālgunī: 1 pāda (the 3 remaining pāda-s are then subsequently assigned to Virgo).

The name of each day is derived from the nakṣatra in which the moon is in that night. Some will predictably be visibly ahead or behind it, which is likened to a calf and its mother. This highlights that the model is arithmetic rather than observational. A month is named based on which nakṣatra the moon is in

on the night of the fifteenth day of the śukla-pakṣa 白月, which is the nominal full moon 望 月 (the pūrṇimānta method), though the actual full moon can visibly vary by a day, in contrast to the Chinese calendar where a month commences from the new moon 朔月 (the amānta method). The Chinese Mātaṅgī-sūtra is

exceptional in using the latter method in contrast to the Sanskrit version, but the gnomonic measurements of the former also reflect revisions suited to a position north of India in Central Asian and moreover the text displays occidental influences. In the Xiuyao jing the first month is Caitra 角, corresponding to the second Chinese lunar month, though Vaiśākha can also be reckoned as the beginning of the year.

As a component to lunar astrology, each nakṣatra is associated with an Indian deity. They are further associated with gotra names and foods, though these vary considerably in the texts. A person is also associated with the nakṣatra they are born under to which predictions about their personal character and fate are made.

Auspicious activities are also prescribed for each day. The nakṣatra-s are also regarded as deities in various esoteric Buddhist 密教 works.

Amoghavajra's Fomu Dakongque mingwang jing 佛母大孔雀明王經 (T 982) invokes them and their powers for protection. The respective deities are also represented in art (for examples see the Butsuzō zui 佛像圖彙).

The following lists the Chinese xiu, Sanskrit nakṣatra, (Sanskrit month name), and associated deity plus variant in the Xiuyao jing if applicable.

01. 昴宿 Kṛttikā (Kārttika) – Agni.

02. 畢宿 Rohiṇī – Prajāpati.

03. 觜宿 Mṛgaśīrṣa (Mārgaśīra) – Soma.

04. 參宿 Ārdrā – Rudra.

05. 井宿 Punarvasū – Aditi.

06. 鬼宿 Puṣya (Pauṣa) – Bṛhaspati.

07. 柳宿 Aślesā – Sarpa (Śeṣa)

08. 星宿 Maghā (Māgha) – Pitaras (Bhaga).

09. 張宿 Pūrvaphālgunī – Bhaga (Vasu).

10. 翼宿 Uttaraphālgunī (Phālguna) – Aryaman.

11. 軫宿 Hasta – Āditya (Savitṛ)

12. 角宿 Citrā (Caitra) – Tvaṣṭṛ.

13. 亢宿 Svāti – Vāyu.

14. 氐宿 Viśākhā (Vaiśākha) – Indrāgnī.

15. 房宿 Anurādhā – Mitra.

16. 心宿 Jyeṣṭha (Jyaiṣṭha) – Indra.

17. 尾宿 Mūla – Nirṛti.

18. 箕宿 Pūrvāṣāḍhā (Āṣāḍha) – Toya (Āpas)

19. 斗宿 Uttarāṣāḍhā – Viśvadeva.

20. 牛宿Abhijit – Brahmā.

21. 女宿 Śravaṇa (Śrāvaṇa) – Viṣṇu.

22. 虚宿 Dhaniṣṭhā – Vasu.

23. 危宿 Śatabhiṣaj – Varuṇa.

24. 室宿 Pūrvabhādrapadā (Bhādraphada) – Ajapāda.

25. 壁宿 Uttarabhādrapadā – Ahirbudhnya.

26. 奎宿 Revatī – Pūṣan.

27. 婁宿 Aśvinī (Āśvina) – Aśvin (Gandharva)

28. 胃宿 Bharaṇī – Yama.

David Pingree. “Identification of the Yogatārās of the Indian Nakṣatras.” Journal for the History of Astronomy 20 (1989): 99-119.

Joseph Needham and Wang Ling. Science and Civilisation in China. Vol. 3: Mathematics and the Sciences of the Heavens and the Earth. Cambridge: Cambridge University Press, 1959.

Michio Yano. "Calendar, Astrology, and Astronomy." The Blackwell Companion to Hinduism. Oxford: Blackwell Publishing, 2003.

Sukuyo-kyō shukusatsu 宿曜經縮刷. Edited by Wakita Bunshō 脇田文紹. 1897.

Yano Michio 矢野道雄. Mikkyō senseijutsu 密教占星術. Tokyo: Toyoshoin, 2013.