The
Arab tradition of astrology utilizes a system of twenty-eight lunar stations (otherwise called “lunar mansions”) called al-manāzil
or manāzil al-ḳamar. There is no such parallel system to be found in
Mesopotamian or Hellenistic Greek sources, but there exists an ancient Indian
system of twenty-eight lunar stations, called nakṣatras.
What
is a lunar station? The Moon revolves around the earth over the course of 27.32
days and it therefore appears from a standpoint on Earth to “lodge” in twenty-seven or
twenty-eight positions throughout its circuit. The Chinese devised their own
unique system of lunar stations (二十八宿) independent of any foreign influences, although during the
twentieth century there was much scholarly debate on this matter, even in
Japan, with some arguing for a Babylonian origin. The present evidence,
however, indicates that Indian and Chinese civilizations created their systems
separate from one another. This point is easily demonstrated by the fact that
the system established by the Chinese court in Antiquity does not correspond to
any documented system of nakṣatras.
It
is important to note that the original systems of Indian nakṣatras and
Chinese lunar stations divided the ecliptic or celestial equator into uneven
zones. The former, however, was redeveloped following the introduction of
Hellenistic astrology and astronomy during the fourth to fifth centuries CE.
The zodiac signs are each uniformly comprised of 30°, thus dividing a 360° ecliptic
into twelve even zones. At some point in the history of Indian astronomy
someone devised a method of bringing together the nakṣatras and the zodiac
signs into a coherent and workable model.
This
revised system was the navāṃsas or ninths of a zodiac sign, in which 27
sidereal nakṣatras are employed (the nakṣatra of Abhijit is
dropped). The ecliptic is comprised of 108 pādas (quarters), with each
zodiac sign comprised of 9 pādas. 108/28 = 3.85, but 27 divides into
integers (108/27 = 4). 360°/27 moreover gives a manageable 13°20. In short,
lunar stations of uneven dimensions were reformatted to fit into a sidereal
zodiacal system of 360°.
The
Sassanian Persians, perhaps during the third century CE, adopted the nakṣatras
into their system of astrology (called xwurdag in Pahlavī or Middle Persian). These
are listed in the Zoroastrian Bundahish, a late Pahlavī
work on Zoroastrian cosmogony and cosmology (see chapter II.2 here).
Did
the Arab tradition acquire the concept of lunar stations from the Persians
after the conquest of the Sassanian empire during the early-seventh century, or
perhaps earlier from the Indians? This is a question that nobody has been able
to satisfactorily answer, but here we might consider some aspects of the Arab manāzil.
As
Kunitzsch in the Encyclopedia of Islam (Brill) notes, the Arabs named the lunar
stations after their anwāʾ . The full list is reported by ʿAbd al-Mālik
b. Ḥabīb (d. 852). The anwāʾ collectively refer to the evening setting and
heliacal rising of specific stars or constellations for the purposes of
estimating the passage of time.
Unlike
the navāṃsas, the manāzil are tropical (i.e., they are defined
according to the vernal equinox, rather than fixed stars). There are also
twenty-eight, each comprised of approximately 12°51. Why would they be tropical rather than
sidereal? Unlike Indian astronomy, the Arabs adopted the tropical zodiac, most
likely based on the work of Claudius Ptolemy (2nd century CE). If the manāzil were based on the navāṃsas,
it would have made sense to define the lunar stations using tropical rather
than sidereal parameters.
Another
interesting point to note is that the sequences of the manāzil and nakṣatras
follow a very similar order:
1. al-s̲h̲araṭān2. al-buṭayn3. al-t̲h̲urayyā (the Pleiades)4. al-dabarān1. Aśvinī2. Bharaṇī3. Kṛttikā (the Pleiades)4. Rohiṇī
The
oldest model of nakṣatras commenced from Kṛttikā, but later the sequence
was revised with Aśvinī at the start. The reason behind this was likely to
ensure that the starting nakṣatra would line up with the vernal equinox (the nakṣatras were still sidereal by definition however).
The fact that the manāzil and nakṣatras both count their third
lunar station as the Pleiades is either a remarkable coincidence or an
indication that the former borrowed from the latter.
Why
isn’t it possible at present to come to a definitive conclusion regarding the history
of the lunar stations? There is simply a paucity of evidence. I suspect we
could easily solve the problem at hand if we had access to astrological and
astronomical materials from Sassanian Iran, but unfortunately the extant
material is quite scarce and moreover not from works written by professional
astronomers.
We know that the Sassanian Persians had a deep interest in
astrology, in light of the testimonies of later Arab sources. One key work in
this regard is the Kitāb al-Fihrist (especially chapter 7.1 & 7.2),
a catalog of texts by Ibn al-Nadim (c. 987–988). He records that the Sasanian
king Šāpur I (r. 239–270) translated into Persian the books of Dorotheus and
Ptolemy as well as an Indian named “Farmāsib”. These works in Persian are now
lost to us, but they show that early Sassanian Iran brought together
Hellenistic and Indian works (hence their concurrent use of zodiac signs and
lunar stations). Early Arab astrologers utilized Persian works to a great extant,
but as far as I know, we cannot identify the source of the manāzil
from their writings.
