Contributions of Ancient Arabian and Egyptian Scientists on Astronomy - Part 1

By: Md. Wasim Aktar
Deptt. of Agril. Chemicals, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India.

Astronomy (‘Ilm al-Hay’ah) or the science of formation (i.e. of the heavens) deals with such things as the structure of the heavens, the number and configuration of the stars, the signs of the zodiac, the distances of the stars, their size and their motions. It also deals with the compilation of planetary tables, the catalogue of stars for the making of calendars and similar tasks.

The Arabs took a keen interest in the study of heavens. They developed this interest firstly, because they had once worshipped heavenly bodies, (1) and secondly, because the dwellers of the desert who usually traveled at night in connection with trade, war and migration from one place to another, found the direction of their journey with the help of the stars. The clear sky of the desert gave them a chance of making precise observations. Thus there was some locally acquired knowledge of the fixed stars, the movements of the planets and the changes of the weather.

After the advent of Islam, the Muslims had to determine the time of the prayers and the direction of the Ka’bah to turn their faces towards it at the time of prayers. For this purpose it was necessary to know the altitude of the sun and the latitudes and longitudes of all the places where the Muslims lived. The same need arose for the orientation of the mosque. This gave a religious impetus to the study of astronomy and the allied subjects such as astronomical geography and mathematics. On the other hand, the Muslims, who once carried on flourishing trade all over the world and occasionally launched Jihad, had to travel on the land and the sea. As an aid to travel, navigation and meteorology, a by product of navigation, they needed star maps. The necessity of such maps was also a cause of their interest in astronomy.

There was a group of astronomers who believed in the influence of heavenly bodies on the terrestrial affairs, and the fate and future of human beings. According to them, the prognostication of sub-lunar events from the revolution of the heavens, the signs of the zodiac in the ascendant and the motion of the planets was possible. The science dealing with such influences was termed as Astrology (’Ilm-Ahkam al-Nujum). Astrology, as a part of astronomy, was studied and developed by ancient Babylonians. The study of this art or science was then made in Greece and Rome, a few centuries before the opening of the Christian era. It was also cultivated in India, China and Egypt. From the 7th to the 13th century it was further developed by the Muslims and later on by the Europeans. In the 14th and the 15th centuries, the astrologers had great influence on the kings of the European countries. (2) The orthodox Muslims did not believe in the influence of the heavenly bodies on fate or the future of human beings.

The regular study of astronomy and mathematics was begun at Baghdad in the second half of the 8th century during the reign of the second ‘Abbasi Caliph Al-Mansür. After that the patronage and generosity of other Muslim rulers, particularly of the seventh ‘Abbasi Caliph Al-Ma’mun, provided stimulation to the astronomical and mathematical researches of every kind. Indian, Persian and Greek astronomical works were translated into Arabic, and for making the astronomical observations the observatories were established by the caliphs and private persons at various places in the Muslim world. Astronomy was studied with great interest with the result that the number of Muslim astronomers raised surprisingly in a short period of time, and by the end of the 10th century, a large number of eminent Muslim astronomers gathered in Baghdad. In the 11th and the 12th centuries astronomy flourished in Muslim Spain where a good deal of creative and original work on this branch of science was done.

The Muslim scientists attached utmost importance to accuracy in observations and calculations, without caring for the length of time needed for it. Thus sometimes their astronomical researches extended for more than forty years. Due to this desire of accuracy the Muslims did not accept as such the astronomical tables or measurements of Ptolemy, a great Greek astronomer and mathematician. They only accepted his planetary theory just to provide a basis for astronomical research. They themselves conducted astronomical researches in Baghdad, Samarqand, Nishapur, Cordova, Damascus and Ray, and after making a careful study of the heavens they not only corrected and amplified Ptolemy’s astronomical tables, but also compiled a number of new ones and drew up new star catalogues. On the basis of fresh observations, the Ptolemaic system was repeatedly criticized by the Muslim astronomers, particularly those of Spain.

The investigations on astronomy were continued, and till the end of the 11th century, nearly all the original and creative work was done by Muslims, and even the works of non-Muslims were written in Arabic. Astronomy reached its highest in the 13th and 14th centuries. In the 12th century, the Christians and Jews started the work of translation from Arabic into Latin and Hebrew, and began to conduct research in this field. But until the end of the 13th century, no mathematical and astronomical work comparable to that of the Muslims could be produced by the Christians or Jews. It is interesting to note that in the 12th century, while Ptolemy’s astronomical work, Almagest, after a thorough study and research, was subjected to severe criticism by Muslims particularly those of Spain, the study of this work was begun in the Latin world.

Besides compiling the astronomical tables, the Muslims prepared celestial globes on which the positions and magnitudes of the stars were represented. The globe is of Greek origin, but since Ptolemy’s time there has been a continuous improvement on it. The Muslim scientists also wrote comprehensive books on astronomy and mathematics, and also composed treatises on various branches of this science.