He Discovered That Planets Move in an Elliptical Orbit 500 Years Before Kepler Did!

Many Muslim intellectuals putted their efforts during 1000 years to enlighten the conscience and spirit of humanity. Baghdad and Andalusia were in the Middle Ages considered as “the capitals of the scientific world”.
The Andalusian Muslims excelled in Arabic literature, grammar, Islamic jurisprudence, mathematics, architecture, art, philosophy, psychology, biology, botany, zoology, medicine, navigation and astronomy. Andalusia produced a lot of stars who sparkled in the world history. One of those shining stars was called “the pioneer of applied astronomy”: Abu Ishaq Ibrahim ibn Yahya al-Naqqash al-Zarqali.

Who Was This Great Man?

Al-Zarqali, better known under his Latinized name “Arzachel”, was born in the 11th century in Cordoba. He worked as a mechanic and metal craftsman. His surname was al-Naqqash, which means “the metalsmith”. He moved from Cordoba to Toledo, one of the most important cultural and scientific centers in Andalusia. The beauty of Toledo inspired him so much that he decided to begin a new life there. It was there in Toledo where he invented a lot of astronomical tools which we still use today. Toledo will also be the city where he discovered a lot of scientific discoveries. His job opened for him a new door and gave him the oppurtunity to be the foremost astronomer of his time.
In 1060, under the service of the Qadhi of Toledo and mathematical scientist, Said al-Andalusi, al-Zarqali worked as an instrument maker who created different tools for other scientists. Qadhi Said of Toledo and his team of Muslim and Jewish scientists were impressed of his intellectual abilities and his perfect job and became very interested in him. Al-Zarqali was an uneducated man who never studied any form of science. Qadhi Said and his team made him study and putted at his disposal all the study materials he needed to educate himself. After only two years, in 1062, al-Zarqali became a member of the group. Shortly after, he became the leader of the group who would teach his own masters, following his instructions to calculate precisely.

The Toledan Tables

This team of Muslim and Jewish scientists compiled the famous Toledan Tables. The Toledan Tables are astronomical tables which were used to predict the movements of the sun, the moon and planets relative to the fixed stars (the modern term for such tables are called “ephemerides”). Al-Zarqali included the results of the astronomical observations on it. The Toledan Tables got their final forms by al-Zarqali around 1080. After it’s translation into Latin in the era of Alphonso the 10th, the Toledan Tables had impressive results in it’s application on the astronomical phenomena of the eclipse and the movement of the celestial bodies. All the following tables for different locations in Europe were based on al-Zarqali’s measurements.

He’s also known for his Almanac, that he wrote in 1088. The work provided the daily positions of the sun, moon and planets for four years from 1088 to 1092. Al-Zarqali also compiled very important tables of latitude and longitude.

The Importance of Al-Zarqali’s Discoveries and Inventions

His most important discovery remains the real length of the Mediterranean Sea. Al-Zarqali is the first one who measured the Mediterranean circuit accurately which is very close to the modern measurements. He noticed that the length of the Mediterranean Sea was 42° and not 62° as Ptolemy claimed.

Al-Zarqali is also the first one who introduced the theory of oval shape of the orbits and discovered that planets move in an elliptical orbit ( 500 years before Kepler did !). His astronomical observations allowed him to prove for the first time the movement of the solar apogee with reference to the stars which he said amounted to 12.04′ a year. He’s also the first one who wrote a treatise about Oscillation theory.

Al-Zarqali developed a set of astronomical theories through his tools that he invented. One of his most popular inventions was the most sophisticated and precise astrolabe ever. He wrote “al-Safiha al-Zarqaliya” (Latinized to “Saphaea”), a treatise on the universal astrolabe that he invented . It was a stereo-graphic projection for the terrestrial equator. It could be used to solve all the problems of spherical astronomy and for the observation of the sun’s movement.The universal plate affected the next generations of Western scientists. He invented another important tool called “equatorium”, an astronomical calculating tool to find the position of the sun, the moon and the planets without calculation.
He also constructed the famous clocks of Toledo. They contained an accurate mooncalendar and were, to a certain extent, the precursors of the current clocks we know today. The water clock, designed to determine the hours of the day and night and to indicate the days of the moonmonths, was also one of his inventions.

Thanks to his scientific discoveries and inventions, Toledo became a very important scientific observation station for the rest of the European countries.
Al-Zarqali turned Toledo into medieval Greenwich”, quoted Mariano Calvo once, a Spanish writer.

Al-Zarqali’s works had a great impact on the following generation of Muslim and non Muslim scientists like Ibn Rushd, Ibn Tufail, Ibn Bajjah, al-Betrugi, Copernicus, Jacob Ziegler and Abraham Zacuto.
In honor of his name and his important contributions for the humanity, the NASA named one of the moon craters “ Arzachel”.

Written by Afifa Thabet

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Afifa Thabet is 33 years old. She studied Oriental Languages and Cultures and volunteers as a teacher. She's interested in everything concerning Islamic history and Arab societies.