Observations of eclipses in Islamic astronomy

A total eclipse is a spectacular sight. It is worth to see it at least once in one’s life, in order to witness this breathtaking natural phenomena as it occurs in the heavens. The wonder felt by humans for eclipses is well recorded in world history. This is why their echoes were transmitted from generation to generation and written down in scientific and popular texts. Muslim scholars of the past recorded dozens of eclipses of the Moon and the Sun, in different parts of the Muslim world, from the North of India until the Andalus, and during a period which covered the whole temporal extent of Islamic civilisation until the 19th century. These eclipses were reported in different literary genres, from scientific treatises of professional astronomers to the accounts and narratives of chroniclers and historians, who reported on the important events they witnessed or about which they had written records. For illustration, we take selected case studies from the works of two famous astronomers, al-Biruni and Ibn Yunus.

Path of the Moon through Earth’s umbral and penumbral shadows during the Total Lunar Eclipse of Aug. 28, 2007 (Pacific Daylight Time: Mid-Eclipse 03:37 am). Image from Google image search.

    Abu al-Rayhan al-Biruni (d. 1048), the famous scientist who excelled in mathematical and applied astronomy, did not fail naturally to observe eclipses and to study them. He said in his Kitab Tahdid nihayat al-amakin li-tashih masafat al-masakin (The Determination of the Coordinates of Positions for the Correction of Distances between Cities) concerning the observation of eclipses:

“The faculty of sight cannot resist it [the Sun’s rays], which can inflict a painful injury. If one continues to look at it, one’s sight becomes dazzled and dimmed, so it is preferable to look at its image in water and avoid a direct look at it, because the intensity of its rays is thereby reduced… Indeed such observations of solar eclipses in my youth have weakened my eyesight.”

In Afghanistan, he observed and described the solar eclipse on April 8, 1019, and the lunar eclipse on September 17, 1019, in detail, and gave the exact latitudes of the stars during the lunar eclipse.

“At sunrise we saw that approximately one-third of the sun was eclipsed and that the eclipse was waning.”

He observed the lunar eclipse at Ghazna and gave precise details of the exact altitude of various well-known stars at the moment of first contact.

One of the greatest astronomers of medieval Islam, Abu’l-Hasan ‘Ali ibn Abd al-Rahman ibn Yunus (950-1009), remained completely unknown to European astronomers of the Renaissance. Working in Cairo a century after al-Battani, Ibn Yunus wrote a major astronomical handbook called Al-Zîj al-Hakimî al-kabîr (Th Great Hakimi astronomical table) which he dedicated to Caliph al-Hakim. Unlike other Arabic astronomers, he prefaced his Zij with a series of more than 100 observations, mostly of eclipses and planetary conjunctions. Although Ibn Yunus’ handbook was widely used in Islam, and his timekeeping tables survived in use in Cairo into the 19th century, his work only became known in the West less than 200 years ago.

Ibn Yunus describes 40 planetary conjunctions accurately and 30 lunar eclipses which were used by the American astronomer Simon Newcomb in his lunar theory. He described an eclipse of the moon that he observed in these terms:

“This lunar eclipse was on 10 Shawwal 370 H [22 April 981 CE]. We gathered to observe this eclipse at al-Qarafa, in the Mosque of Ibn Nasr al-Maghribi. We perceived first contact when the altitude of the moon was approximately 210. About a quarter of the lunar diameter was eclipsed, and re-emergence occurred about a quarter of an hour before sunrise.”

Ibn Yunus reports on another eclipse, the solar eclipse of 11 November 923 CE:

“(This) solar eclipse was calculated and observed by Abu al-Hassan Ali ibn Amajur, who used the al-Zij al-Arabi of Habash… We as a group observed and clearly distinguished it… We observed this eclipse at several sites on the Tarmah (an elevated platform on the outside of the building)… According to calculation from the conjunction tables in the Habash Zij the middle was at 0;31 h (i.e. 31 min) and its clearance at 0;44 hours (i.e. 44 min), calculation being in advance of observation.”

Ibn Yunus’ Hakemite Tables compiled around 1005 contained records of the eclipses of 993 CE (solar), 1001 CE (lunar), 1002 CE (lunar), and 1004 CE (solar).

Illustration of different phases of the moon in the Persian translation of Kitab al-tafhim by al-Biruni. Source: Seyyed Hossein Nasr, Islamic Science: An Illustrated Study, London: World of Islam Festival, 1976. The original source of the eclipse diagram in al-Biruni’s manuscript is held in the Library of the Parliament Library in Teheran.

Some reports of eclipses in Islamic history:

Medieval Islamic chroniclers recorded a number of detailed and often vivid descriptions of eclipses. Usually the exact date of occurrence is given (on the Hijri lunar calendar). Their reports of such astronomical events show the importance they devoted to them. Moreover, their accounts offer nowadays a good ground for multifaceted historical analysis. One of the uses in which their reports are used is to verify astronomical calculations of eclipses of the past, but also to decide about the dates of the historical events related to these eclipses or other astronomical phenomena. For instance, the eclipses and the apparitions of comets mentioned by the Moroccan historian Ibn abi Zar’ (14th ventury), who reports in his history astronomical events recorded in the tradition of the Islamic West. His narratives of the eclipses allow the historians to correct some erroneous dates that we find in his text, given the important differences existing between its different manuscript sources.

A graphic narrative of the total solar eclipse of 20 June 1061 CE was recorded by the Baghdad annalist Abu-al-Faraj Ibn Al-Jawzi (508-597 H), who wrote approximately a century after the event, in his Al-Muntadham fi tarikh al-muluk wa-‘l-umam (in 10 volumes):

“(453 H.) On Wednesday, when two nights remained to the completion of (the month of) Jumada al-Ula, two hours after daybreak, the Sun was eclipsed totally. There was darkness and the birds fell whilst flying. The astrologers claimed that one-sixth of the Sun should have remained [uneclipsed] but nothing of it did so. The Sun reappeared after four hours and a fraction. The eclipse was not in the whole of the Sun in places other than Baghdad and its provinces.”

The historian of astronomy F. R. Stephenson comments here that the date provided by Ibn al-Jawzi “is exactly correct.”

Three independent accounts report on the eclipse of 11 April 1176 CE. The historian Ibn al-Athir, who was 16 years old at that time, described the event as follows in his al-Kamil fi al-tawarikh:

“In this year (571 H) the Sun was eclipsed totally and the Earth was in darkness so that it was like a dark night and the stars appeared. That was the forenoon of Friday the 29th of Ramadan at Jazirat Ibn ‘Umar [now Cizre, in Turkey], when I was young and in the company of my arithmetic teacher. When I saw it I was very much afraid; I held on to him and my heart was strengthened. My teacher was learned about the stars and told me: ‘now, you will see that all of this will go away’, and it went quickly.”

Michael the Syrian (also known as Michael the Great or Michael Syrus) (d. 1199 CE) was an Assyrian patriarch of the Syrian Orthodox Church from 1166 to 1199. He is best known as the author of a large Chronicle, which he composed in Syriac, where he refers to the total solar eclipse that he observed at Antioch on 11 April 1176 in those terms:

“In this year 1487 (Seleucid era), on New Sunday, the 11th of the month of Nisan [April], at daybreak, at the end of Office, that is, after the reading of the Gospel, the Sun was totally obscured; night fell and the stars appeared; the Moon itself was seen in the vicinity of the Sun. This was a sad and terrifying sight, which caused many people to lament with weeping; the sheep, oxen and horses crowded together in terror. The darkness lasted for two hours; afterwards the light returned. Fifteen days after, in this month of Nisan at the decline of Monday, at dusk, there was an eclipse of the Moon in the part of the sky where the eclipse of the Sun had taken place.”

On his part, ‘Imad Al-Din al-Asfahani al-Katib (1125-1200 CE), secretary of state and official chronicler during Salah al-Din al-Ayubi’s reign, in his chronicle of the crossing of the Orontes River, near Hamah (in present-day Syria) by Salah al-Din al-Ayyubi and his army, refers to the solar eclipse of 11 April 1176 when he says:

“The Sun was eclipsed and it became dark in the daytime. People were frightened and stars appeared.”

The date of the eclipse is given correctly apart from the weekday (actually Sunday) and is equivalent to 11th April 1176. Calculation shows that the whole of the Sun would have been obscured over a wide region over the Middle East, beginning in the region of Cizre in Turkey. Farther south, totality was also witnessed by Salah al-Din and his army while crossing the Orontes River near Hamah. The chronicler ‘Imad al-Din, who was with Salah al-Din al-Ayyubi at the time, dates the event one year too early (570 H), but the only large eclipse visible in this region for several years occurred in 1176 CE.

In our quest for the records of eclipses, an important source is the monumental Tarikh al-Rusul wa’l muluk (The History of Prophets and Kings) by Abu Ja’far Muhammad b. Jarir al-Tabari (838-923), one of the earliest, most prominent and famous Muslim historians and exegetes of the Qur’an. Indeed, in his History, al-Tabari reports several eclipses observed in early Islamic history. A solar one occurred on 28 Dhu ‘l-Hajja 203 H / 25 June 819 CE. Upon examination it turned out that there was indeed a solar eclipse in the morning of 26 June 819. Hence the slight error results from an inaccuracy in determining the beginning of the Lunar month. Al-Tabari mentioned also another solar eclipse that happened in 29 Muharram 269 H / 17 August 882 CE. The same eclipse is referred to by Ibn al-Jawzi on the same date.

Ibn al-Jawzi, in a famous report quoted often in the modern historiography, reports that there was a solar eclipse in the morning of Wednesday 28 Jumâda I 453 / 19 June 1060. Indeed a total solar eclipse happened exactly at this date, but on 20 June 1060 CE (29 Jumada I, 453 H). Another eclipse reported by Ibn al-Jawzi was the one of Tuesday 28 Rabî II, 570 H / 25 November 1174 CE; but in the astronomy records an eclipse occurred on the morning of Tuesday 26 November 1174 CE (29 Rabi II, 570 H). Concerning the eclipse of 29 Rabî 1 574 H / 13 September 1178 CE, Ibn al-Jawzi and al-Tabari agree on its date, and their account is supported by astronomy records.

Later on and more to the West, the Moroccan historian of the 19th century, Ahmad ibn Khalid al-Nasiri (1835-1897), records in his Al-Istiqsâ’ li-akhbâr duwal al-maghrib al-aqsâ, a general history of Morocco and the Islamic west from the Islamic conquest to the end of the 19th century, that there had occurred a solar eclipse on Wednesday 29 Shawwâl 229 H / 19 June 912 CE. This is true, exactly like other eclipses that he recorded until the 18th century.

Plenty of other records of lunar and solar eclipses and many other outstanding astronomical events exist in Muslim heritage that would repay investigation, such as the recent study of the observation in 1006 in many regions of the Muslim world of the blast of a new Supernova. Historians began just recently to pay serious attention to all the benefits they can draw from such records. It would be extremely interesting to collect all these records and to classify them. Such a task has just begun. It is being undertaken by scholars from the Muslim and Arab world and by their colleagues in the West, as the resources quoted in this article show clearly.

(This article was written at MuslimHeritage.com and modified by HikmahWay Institute & AMYN Staff)

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