Persian astronomy and astrology – Ulugh Beg

In the roughly 14 hundred years from Ptolemy writing The Almagest in the 2nd century until the invention of the telescope made more accurate astronomical observations possible at the beginning of the 1600s, many transcripts and transcripts of transcripts were made of his star catalogue by astronomers of the mediaeval East and Europe, but only a few of them contributed to the original work with additions or corrections based on their own observations. One of these astronomers was Mīrzā Muhammad Tāraghay bin Shāhrukhbetter known as Ulugh Beg, Timurid ruler of the region of Samarkand in the 15th century.

Ulugh Beg became governor of Samarkand in 1409, when his father Shah Rukh finally managed to take possession of the eastern portion of the empire established by his father Timur (Tamerlane) and moved his capital to Herat. Coming from an educated family – his parents were patrons of art and science, his mother’s efforts had even made the education of woman acceptable for a short time – his intension was to turn the city into an intellectual center.
In 1417 he began to build a madrasah – an institute for higher education – in Samarkand for studying different disciplines of secular science from astronomy and mathematics to medicine and poetry.

The two-story building-complex arranged around a rectangular courtyard with an imposing entrance portal and two minarets at the front facade included dormitory cells and rooms for the scholars and students, four lecture rooms at the four corners and a mosque at the west wall of the courtyard. Ulugh Beg invited the best scholars he could find as lecturers, and the Ulugh Beg Madrasah soon became the leading center of Islamic education in Central Asia. Today the building is still standing at the Registan, the center of Samarkand, with two other madrasahs built in the 17th century on two other sides of the square.

Although educated and active on many fields, Ulugh Beg’s main interests – inspired probably by a childhood visit to the remnants of the Marāgha Observatory, where Persian astronomer al-Tusi and his team completed around 1270 the star catalogue called the Ilkhanic tables (Zīj-i Īlkhānī) – had always been mathematics and astronomy. In 1420 he started to build the enormous observatory Gurkhani Zīj near Samarkand, with huge structures used as instruments to increase the accuracy of astronomical observations and measurements to the maximum. The observatory was unparalleled in its time.

‘Its circular main building, beautifully decorated with glazed tiles and marble plates, had a diameter of about 46 m and three stories reaching a height of approximately 30 m above ground level. The north–south axis of the main building was occupied by a huge sextant with a radius of 40 m (called Fakhrī sextant after that of Khujandī). On the scale of this instrument, which partially lay in an underground slit with a width of half a meter, 70 cm corresponded to 1° of arc, so that the solar position could be read off with a precision of 5″. On the flat roof of the main building various smaller instruments could be placed, such as an armillary sphere, a parallactic ruler, and a triquetrum. Among other instruments known to have been used in Samarqand are astrolabes, quadrants, and sine and versed sine instruments.’

source: Benno van Dalen © Springer International Publishing AG

Around this time Ulugh Beg was already working together with numerous scholars he invited to join his madrasah, among them renowned scientist Qāḍī Zāda al-Rūmī and the excellent Islamic astronomer and mathematician Jamshid al-Kāshī, author of an updated star catalogue called Khaqani Zīj. With a team of about 60-70 fellow scientists, based on systematical observations and computations carried out between 1420 and 1437 they completed an astronomical handbook with tables called Zīj-i-Sultani. 

The catalogue includes the coordinates of 1018 stars, the listing is based on Abd al-Rahman al-Sufi‘s Kitab al-Kawakib al-Thabita – The Book of Fixed Stars from the late 10th century, an augmented and improved version of Ptolemy’s Almagest.
As Ulugh Beg explains in the preface:

“Determination of the Places of the Fixed Stars in Longitude and Latitude.

Before the time of Ptolemy 1,022  fixed stars had been observed. Ptolemy has given them in a catalogue in the Almagest. The stars are distributed in six magnitudes; the largest are of the first and the smallest of the sixth magnitude. Each magnitude is divided into thirds, and in order to recognize the stars, 48 figures or constellations have been imagined, of which 21 are north of the ecliptic, 12 in the Zodiac, and 15 south of the ecliptic. The larger number of the stars are within the figures, the others are in the neighborhood, and are designated as unformed stars of the constellation.

Abd Al Rahman Sufi composed a treatise on the stars which all learned men have received with gratitude. Before determining by our own observations the position of these stars, we have laid them down on a sphere according to this treatise, and we have found that the greater part of them are situated differently from their appearance in the heavens. This determined us to observe them ourselves with the assistance of Divine Providence, and we have found that they were advanced from the epoch at which Sufi’s work was written, so that on giving them, according to this general observation, their absolute positions, we no longer found any difference from their appearance to the eye.

It is on this principle that we have reobserved all the stars already determined, with the exception of 27 which are too far to the south to be visible at the latitude of Samarkand (…) and we have taken these 27 stars from the work of Abd Al Rahman Sufi, taking account of the difference of epoch.

Besides these there are 8 stars mentioned by Abd Al Rahman Sufi in his book, of which Ptolemy gives the positions, but which Abd Al Rahman Sufi could not find, and which notwithstanding all our researches, we have been unable to discover. For that reason we do not indicate those stars in the present catalogue.(…)

In our catalogue we have given the position of the stars for the beginning of the year 841 of the Hegira, so that at any time we may be able to find the place of any stars on the supposition that they advance one degree in seventy solar years.”


The preface to the tables consists of four parts. The first three parts contain methodical descriptions of different astronomical measurements and calculations e.g. determining the length and initial days of years and months, the equation of the Sun and Moon, positions and characteristics of the stars and the seven planets, calculating eclipses, Moon phases and determining the position of the twelve celestial houses: the Zodiac signs. The fourth part of the preface is about astrology: horoscopes and nativities. Ulugh Beg, like many other Persian rulers, believed in astrology and fortune‐telling.
The catalogue also includes sheets of the motions and eclipses of the Sun, the Moon and the planets, longitude and latitude of several cities in various countries, trigonometric tables etc.

In 1449 Ulugh Beg was killed by his oldest son Abdal-Latif Mirza on his way to Mecca, his observatory was demolished by religious extremists, the library was looted, the scholars were forced to flee. Ali Qushji, a former student and leading astronomer at the observatory managed to take a copy of the original manuscript with him. This manuscript was translated from the original Farsi to Arabic and later to Latin, French and English – today, all known versions of the Zij-i-Sultani are translations.
The observatory buildings were excavated in 1908 by Russian archaeologist V. L. Vyatkin. Foundations of the three story cylindrical structure and underground sections of the giant marble sextant can be seen on site.

The work of Ulugh Beg and his colleague astronomers may not be ‘revolutionary’ in the sense of creating something absolutely new, but the accuracy of collecting, reobserving, recalculating, updating and correcting the data of existing catalogues, and listing altogether 1018 stars make Zij-i-Sultani one of the most important star inventories in the history and a highly influential work of Persian astronomy and astrology, that continued to be used in the Islamic world until the 19th century.

Heather Hobden
Benno van Dalen © Springer International Publishing AG

1. ©Francisco Anzola CC BY 2.0

2. ©Mr Hicks46 CC BY-SA 2.0
3. source: Christies
4-5. source: National Education Ministry of Bursa
6. ©Leon Yaakov CC BY-NC 2.0                             
7. ©Adam Baker CC BY 2.0

HOROSCOPE OF ISKANDAR – Timurid Islamic painting

Though in the Islamic world of the Middle Ages it was a common practice for dignitaries and princes to have their birth chart calculated, the horoscope of Timurid Prince Mirza Iskandar (1384-1415) is the only individual birth chart from that era we know to exist today.

Horoscope of Timurid Prince Iskandar, Islamic miniature The book of Birth of Iskandar 1411 Middle Ages Islamic astrology Islamic art Islamic painting iconography Timurid dinasty
Horoscope of Timurid Prince Iskandar, Islamic miniature The book of Birth of Iskandar 1411 Middle Ages Islamic astrology Islamic art Islamic painting iconography Timurid dinasty

The double-page miniature depicting the chart is part of a manuscript containing 86 folios, devided into three parts, presenting detailed astrological calculations and predictions for the life of the prince. The book got to the West at the end of the 18th century from Iran through a clerk of the East India Company and was bought in 1932 at a Sotheby’s auction by Sir Henry Wellcome, founder of the Wellcome Institute for the History of Medicine in London. The manuscript came to light in 1980 when categorizing the Persian collection of the institute.

Prince Iskandar was a grandson of Timur (also known as Tamerlane, first ruler of the Timurid dynasty, who claimed to be a direct descendant of Genghis Khan), and reigned for 5 years (1409-14) over the province of Fars, Iran. Like most Timurid rulers, he was a committed patron of science and art, especially the arts of the book, commissioning manuscripts that were copied, compiled, and illustrated in the ’kitabkhana’, the royal bookmaking workshop of the Timurids. These workshops functioned as collaborative design studios, supporting astronomers, poets, artists and craftsmen. Besides the illustrated and illuminated manuscripts and albums with lavishly detailed miniature painting and calligraphy they were also producing concepts for architectural details, carpets and decoration.

Iskandar was particularly interested in astrological and astronomical illuminated works. The circumstances of preparing his horoscope were rather unusual, because it wasn’t cast on the prince’s birthday (25 April 1384), but at the beginning of his reign, by astrologer Imad al-Munajjim. The manuscript was created in 1411 in his kitabkhana, and is considered as a beautiful example of the hand-made book production of the 15th century.

The miniature’s central part shows a circular depiction of heaven, divided into 12 houses, with one of the Zodiac signs in each house according to the moment of the prince’s birth.

The background of the painting is a deep blue pigment, prepared from Lapis lazuli, a natural gemstone, richly decorated with golden stars and dots. Around the chartwheel in the corners four angels carry nativity gifts: crowns and golden dishes, symbols for wealth and power. There are seven human figures placed in the houses representing the 6 planets and the Moon, the empty houses and the central circle of the painting are filled with lavishly gilded and illuminated arabesques.

The seven figures representing the celestials:

al-Shams and al-Quamar (Sun and Moon)
Both relatively asexual figures are wearing crowns, similarly ornamented tunics, sitting in identical position and holding a golden halo in front of their faces. The only differences are the color of the garment and the size of the figures: the Sun is significantly bigger than the Moon.

al-‘Utarid (Mercury)
Male figure in blue tunics and white turban, sitting and pointing to a bookstand beside him. He’s traditionally depicted writing on his lap.

al-Zuhara (Venus)
Female figure, a courtesan playing a lute, wearing a pink dress and a crown.

al-Mirrikh (Mars)
A warrior, standing with a sword in one hand and a severed head in the other.

al-Mushtari (Jupiter)
Planet of wisdom and science, a male figure holding an astrolabe, an important instrument used in astronomical measurments.

al-Zuhal (Saturn)
A half-dressed man with a crown on his head, with three hands, holding two other crowns and a rat.

There are minor deviations in the details, but the figures representing the planets show the characteristics of the original Islamic iconographic tradition that was established around the end of the 12th century, mainly based on the cult of the planets in early ages, with influence of Greco-Roman, Iranian and Central-Asian stylistic elements.

The arrangement of the planets in the houses, on the other hand, shows an interestingly biased deviation from the calculations, that can probably be explained with the relation of the artists and the commissioner…

Each Zodiac sign is depicted occupying one whole house, thus leaving the painter with the dilemma of where should a planet be positioned when it’s calculated house and sign doesn’t coincide with this arrangement.
In our case, according to the calculations the Sun should be in the 4th house, Mercury and Jupiter in the 5th, the Moon and Saturn in the 6th and Mars in the 10th house. But with shifting the Sun, Mercury, Jupiter and Mars half sign, Taurus, the prince’s sun-sign can be highlighted in the 5th house with the Sun, symbol of kings and princes, power and dignity in it, Mars, planet of war and victories gets a more favorable position in the 11th, and with Venus, protector of art already in a good position in the third house, the ‘less’ important planets can share the 6th house.
This way the horoscope shows a lot more ‘kingly’ arrangement, suiting the expectations of a prince with high ambitions for territorial conquests and more political power, and appropriate for a patron of arts and science.

zodiac in the horoscope of Timurid Prince Iskandar The Book of Birth of Iskandar Islamic art astrology Islamic painting miniature iconography kitabkhana The Middle Ages Islamic culture Wellcome-Library
zodiac in the horoscope of Timurid Prince Iskandar The Book of Birth of Iskandar Islamic art astrology Islamic painting miniature iconography kitabkhana The Middle Ages Islamic culture Wellcome-Library

Anna Caiozzo: The Horoscope of Iskandar Sultan as a Cosmological Vision in the Islamic World
in: Horoscopes and Public Spheres: Essays on the History of Astrology, edited by Günther Oestmann, H. Darrel Rutkin, Kocku von Stuckrad, 2005 Walter de Gruyter GmbH&Co Berlin

images are credited to Wellcome Library, London
Copyrighted work available under Creative Commons Attribution only license CC BY 4.0