The Pleiades Conjunction Calendar

One of the indigenous calendars from the Arabian Peninsula is based on the monthly conjunction of the Pleiades with the moon. The moon conjuncts with the Pleiades about once every 27 1/3 days. This conjunction was visible monthly from autumn through spring and occurred about the same time each year; thus it coincided with the main parts of the pastoral cycle on much of the Arabian Peninsula. According to Abû Laylî (in al-Marzûqî 1914:2:199), these conjunctions began at the time of the autumn wasmı rain. This observation is still found among contemporary Sinai Bedouins (Bailey 1974:588). Ibn Qutayba (1956:87) noted that when the moon conjuncts with the Pleiades on the fifth day of the lunar month, winter goes away. The new moon coincides with the Pleiades during the month of Nîsân or April during the naw’ of simâk. This was considered to be one of the most fortunate star movements in the sky, perhaps because of its unique annual character. Shortly thereafter the Pleiades disappears from view at the start of the heat.

In Yemeni folklore the first conjunction in the reckoning is called “19,” because the conjunction of the moon and the Pleiades is on the 19th day from the new moon of the lunar month. It appears that the conjunction on the 19th night occurs at the end of the month of Aylûl (September), following the rising of the four stars of Ursa Major. After another lunation the moon conjuncts with the Pleiades two days closer to the new moon. This is because the difference between the orbit of the moon around the earth (which is 27 1/3 days) and the cycle of the waxing and waning of the moon’s phases (which is 29 1/2 days) is about two days. After conjunction 17 is conjunction 15 and so on until the completion of the reckoning. During the spring, around the start of April, the Pleiades conjuncts with the new moon; this was thought by the pre-Islamic Arabs to be a very auspicious time (Ibn Qutayba 1956:86). After the Pleiades conjuncts with the new moon, it soon disappears from view in what the Yemenis call “the night with nothing else” (layla wa-lâ shay’).

The Pleiades conjunction calendar defines a very important period to Yemeni farmers, as reflected in the almanac poem of the Yemeni poet Hasan ibn Jâbir al-‘Affârî, who died in 1122/1710 (Varisco 1997:18-19):

For the common people there is a second view
to the east for a conjunction.
That is, the Pleiades conjuncts with the moon,
the first being conjunction 19.
When the fifth of ‘allân [harvest season] comes,
so easily known, is the start of the conjunction.
According to them, when this conjunction comes,
it distinguishes summer from autumn.
On the nineteenth night
these two conjunct every time.
During it the leaves of the regional crops are stripped,
and they gather the fodder grass of ‘allân.
After this is conjunction 17;
harvest, even if only some of the crop is ripe.
The male sheep mount,
the females, so listen well to my system.
For the conjunction on night 15
be pleased for your sons because of the abundance.
[Conjunction] 13 is the best you will ever have.
Plowing is fortunate among the labors.
When you hold back pruning your grapevines,
be wise in [conjunction] 11.
If you prune before this, then all that
you prune will go through the general cold.
Because in their branches are springs
from which the hidden seed will emerge.
In conjunction 9 the grapevines bud
and from the springs quickly [?] a marvel begins.
In conjunction 7 or the seventh of al-Sawâb
the first of the spring rain comes in bucketfuls.
It is suitable at this time for the dithâ’,
a sowing for one who wants to be an important man.
At the last of it are twelve
days called in the special reckoning
Qarâqir, six [days] passing until
when they go by, the six [days] of Sawâb come.
They say in conjunction 5, know that
is about the time for spring labors, so understand.
If you sow dithâ’ [wheat and barley] in it, it will not go wrong,
but the bread from its grain will come out tasty.
[Conjunction] 3, the ones with experience say,
is for whoever wants prominence in sowing sorghum.
At this time the people of al-˘azm do not approve
of the sowing of dithâ’, because it will turn white
And then its seed will be thin,
so know they have said exactly this.
[Conjunction] 1 to them is like a [vain] boaster,
during it is the conjunction of a night and then nothing.
After a month the Pleiades sets
and the rains set in and irrigate the land.
It sets at the time of its setting and disappears
continuously for 12 days in its absence.
Then by its absence it is a divider
of what is rightly between spring and jahr [hot and dry period],
Concluding all the spring labors
as the rains set in with its going down.

The nine months between September and May cover the most important work period for farmers in the Yemeni highlands. The conjunction month 19 falls during the local season of ‘allân, the beginning of the autumn sorghum harvest. In much of the Yemeni highlands sorghum stalks are stripped of their leaves about a month before the harvest of the heads, as mentioned in the poem. Advice is given on when to plow, prune grapevines and sow, as well as when to expect rain.

The Pleiades conjunction calendar has been reported from various parts of the Middle East, including Palestine (Dalman 1928:1:23, Jaussen 1903:376) and Afghanistan (Bausani 1974, Ferdinand 1959). It is interesting to note that the conjunction of the moon and the Pleiades was used to determine the intercalary months in Babylonian astronomy (Hunger and Reiner 1975). Timekeeping based on the conjunction of the moon and the Pleiades is also found in East Africa (Nilsson 1920:136).


Bailey, Clinton. “Bedouin Star-lore in Sinai and the Negev.” Bulletin of the School of Oriental and African Studies 37:580-596, 1974.

Bausani, Alessandro. “Osservazioni sul sistema calendariale degli Hazâra di Afghanistan.” Oriente Moderno 54:341-354, 1974.

Dalman, Gustav. Arbeit und Sitte in Palästina. Gµtersloh: Bertelsmann, 1928-1942.

Ferdinand, Klaus. Preliminary Notes on Hazâra Culture. Historisk-filosofiske Meddelelser udgivet af Det Kongelige Danske Videnskabernes Selskab, 37:5:1-51, 1959

Hunger, Hermann and Erica Reiner. A scheme for intercalary months from Babylonia. Wiener Zeitschrift für d. Kunde des Morgenlandes 67:21-28, 1975.

Ibn Qutayba, Abû Muhammad ‘Abd Allâh. Kitâb al-Anwâ’. Hyderabad: Matba‘at Majlis Dâ’irat al-Ma‘ârif al-‘Uthmânıya, 1956.

Jaussen, H. Les Arabes au pays de Moab. Paris: Lecoffre, 1903.

al-Marzûqî, Abû ‘Alî. Kitâb al-Azmina wa-al-amkina. Two volumes. Hyderabad: Mayba‘at Majlis Dâ’irat al-Ma‘ârif al-‘Uthmânıya, 1914.

Nilsson, Martin P. Primitive Time-Reckoning. Skrifter Utgivna av Humanistiska Vetenskapssamfundet, 1. Lund, 1920.

Varisco, Daniel M. “Agricultural time reckoning in the urjûza of Hasan al-‘Affârî: A study on the Yemeni agricultural almanac.” In Medieval Astronomy and Agriculture in Arabia and the Yemen, article XI. Aldershot: Variorum, 1997.

Excerpt from Daniel Martin Varisco. Islamic Folk Astronomy, In The History of Non-Western Astronomy. Astronomy Across Cultures, pp. 615-650. Edited by Helaine Selin. Dordrecht: Kluwer Academic Publishers, 2000.

For Islamic Folk Astronomy #4, click here.