Two astronomical phenomena in the Jordanian sky on Wednesday and Thursday linked to the Al-Wasm season
Amman5 min read
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The Jordanian sky will witness, on Wednesday and Thursday, October 28 and 29, two astronomical phenomena linked to Jordanian folk heritage. The first is the approach of the Moon to the Pleiades star cluster, known as "Qiran Al-Wasm," and the second is the entry of the "Spica" lunar mansion, which represents the second of the four Al-Wasm season mansions.
The President of the Jordanian Astronomical Society, Ammar Al-Sakji, said that the Moon will appear to approach the Pleiades stars at dawn on Wednesday at an angular distance of less than one degree, a phenomenon known in Jordanian Bedouin heritage as "Qiran Sab'at 'Ashar" (Conjunction of Seventeen) or "Qiran Al-Wasm," and also called in some folk accounts "Al-Qiran Al-Thurayya."
Al-Sakji explained that the Moon will be in the waning gibbous phase, with an illumination of approximately 95%, which allows for tracking and photographing the phenomenon, although the bright lunar glare may limit the visibility of the faint stars in the Pleiades cluster.
He pointed out that the Pleiades is a star cluster located in the constellation Taurus, at a distance of approximately 440 light-years from Earth, and includes a large number of stars, the brightest of which can be seen with the naked eye in a clear sky.
He indicated that the name "Qiran Sab'at 'Ashar" refers to a system of folk names associated with the Moon's conjunction with the Pleiades. These are calendar names inherited from ancestors to identify seasons and times for agriculture and grazing, and they do not reflect the actual angular distance between the Moon and the Pleiades.
He added that the Moon returns to the vicinity of the Pleiades periodically, according to a sidereal cycle averaging about 27.32 days, while its phase and illumination percentage change from one approach to another.
Entry of the Spica mansion
Regarding the second phenomenon, Al-Sakji said that Thursday, October 29, marks the entry of the "Spica" mansion, which is the fourteenth of the twenty-eight lunar mansions and the second of the Al-Wasm season mansions according to the folk calendar.
He explained that Spica, known astronomically as "Spica," is the brightest star in the constellation Virgo. It is about 250 light-years away from Earth and is a binary star system consisting of two stars orbiting their common center of mass.
According to astronomical simulations conducted for Amman and its suburbs, Spica will rise on Thursday around 6:00 AM Jordan time, which is about 50 minutes before sunrise.
He noted that at 6:50 AM, the star will be at an altitude of approximately 10 degrees above the horizon, in an east-southeasterly direction, while the angular distance between it and the Sun will be about 12 degrees.
Al-Sakji emphasized that the astronomical rising of the star does not necessarily mean it can be seen with the naked eye, as its apparent proximity to the Sun amidst the twilight glow makes its sighting on Thursday morning unlikely.
He indicated that observing the star using sensitive astronomical cameras and image processing techniques might be possible under certain conditions, but it is not guaranteed and requires strict safety precautions due to the proximity of the observation direction to the Sun.
Al-Wasm season and rains
Al-Sakji pointed out that the Al-Wasm season begins according to the folk calendar on October 16 of each year and lasts for 52 days until December 6. It consists of four stellar mansions, each lasting 13 days: Al-Awwa from October 16 to 28, Spica from October 29 to November 10, Al-Ghafr from November 11 to 23, and Al-Zubana from November 24 to December 6.
He explained that the Al-Wasm season has historically been associated with the anticipation of autumn rains, falling temperatures, the sprouting of herbs, and the renewal of pastures. Early rains, when appropriate conditions of humidity and temperature are met, help wild plants grow and improve pastures, and may create conditions for the growth of desert truffles, known as "Faq'a."
He noted that the Bedouin proverb "Its signs are from its nose" (meaning the season's fertility is indicated by its early rains) refers to predicting the fertility of the season from the first rains, but he emphasized that the entry of Al-Wasm or one of its mansions on its calendar date does not necessarily mean rain will fall on that day.
Al-Sakji stressed that there is no causal relationship between the rising of Spica or the Moon's conjunction with the Pleiades and the formation of clouds or rainfall, explaining that rains in Jordan are influenced by the movement of atmospheric depressions, moisture transport, changes in atmospheric pressure, temperatures, and air masses.
He indicated that ancestors used stars and lunar conjunctions as temporal markers to identify the succession of seasons, based on their accumulated experience in observing the sky and climatic changes.
He pointed out that traditional dates for star mansions do not necessarily coincide with their actual astronomical appearance dates, due to factors including the slow change in the direction of the Earth's axis of rotation over the centuries.
He confirmed that the coincidence of the Al-Wasm conjunction with the entry of the Spica mansion represents an opportunity to revive Jordanian astronomical heritage and link it to modern astronomical calculations, while distinguishing between folk seasonal markers and observable astronomical phenomena.
Al-Sakji announced that the Jordanian Astronomical Society will work to observe and document the Moon's conjunction with the Pleiades cluster and the rising of the star Spica, as part of its efforts to document astronomical phenomena and link modern scientific knowledge with Jordanian folk heritage.
