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Sephardic AstronomersPart I of II issued December 9, 2005
By Shelomo Alfassa
On the 9th of December some 434 years ago, Adriaan Adriaanszoon, better known as Metius, was born in Northern Holland. Metius (1571-1635) was a Dutch mathematician and astronomer who once said, "Inspiration from God" was recommended for astronomical research along with knowledge of geometry and the aid of mechanical instruments. Metius's family was in the glass grinding business and in 1608 developed a device for "Seeing faraway things as though nearby." It consisted of convex and concave lens set in a tube which magnified objects three to four times; it was the telescope. Metius was not Jewish, but the anniversary of his birth, as well as the mention of the early telescope, provides us an opportunity to learn about a subject we often don't read much of…the Sephardic astronomers.
Look up the occupations of well known Sepharadim from the past and you will often find bankers, linguists, tax collectors, interpreters and political advisors. Though these employment descriptions may be historically true, the greater number of Sepharadim were not linguists nor bankers. It is the wealthy and the well-known to which history records a romantic account of the past. Typically, it seems the occupations which are generally remembered to history are those of the educated class. The everyday man, teacher, farmer, fish vendor, donkey driver, butcher, scribe, merchant, woodworker and street sweeper are generally forgotten. Even so, one occupation of the more sophisticated class, which is still overlooked, as well as little understood, is that of the astronomer, the scientists of the night sky.
The historical record demonstrates that the scientific world flourished during the period that the Muslims were the ruling power in Al-Andalus (Spain). It was there among the mixed lands of Christians, Jews and Muslims that the scientific instrument known as the astrolabe was developed, the most popular astronomical tool of its time. Astrolabes were used to show how the sky looked at a specific location at a given time. They were used in association with scientific data tables. This was done by drawing the sky on the face of the instrument and marking it so positions in the sky were easy to locate. It has been said that the astrolabe was the pocket watch of the medievals.
Persons with access to these instruments and who studied astronomical problems were not exclusively Muslim, they indeed included members of the Jewish community. The Muslims had gotten their interest in astronomy from Greek texts which they had been translating; Arabic-speaking Jews participated in these translations. A great many books were translated, to the point where vast libraries in Spain were filled. The Jewish Encyclopedia writes:
With the revival of Greek science which took place in Islam, Jews were intimately connected...Jews seem to have been particularly concerned with the formation of astronomical tables of practical utility to astronomers. A Jewish convert to Islam, Sind ben Ali (about 830), was one of the principal contributors to these early tables. No less than twelve Jews were concerned in the Toledo tables, drawn up about 1080, and the celebrated Alfonsine Tables were executed under the superintendence of Ishak ibn Sid.
Ishak ibn Sid flourished in Toledo as an astronomer around 1270. He played a leading role compiling the Alfonsine Tables. Commissioned by the Catholic King Alfonso X of Leon and Castile, these tables were a revision of the earlier Toledan Tables. They included information on the motion of the Sun, Moon, and five (visible) planets. These new astronomical tables became the standard reference for the night sky for the next 400 years. A contemporary Jewish astronomer declared he saw recorded in Ishak ibn Sid's own handwriting, three observations of eclipses of the moon made by him at the order of Alfonso. In official documents Ishak ibn Sid, who is also connected with the invention of various scientific instruments, is termed by Alfonso as "Our learned Rabbi..."
Ishak Albalia was born in Cordoba approximately 1035. He studied both astronomy and Talmud; his knowledge was classical Sepharadi, mastering both religious and secular studies. It was said he spent large amounts of money maintaining a magnificent library. In 1069 the Caliph of Seville made Ishak both court astrologer and chief rabbi. It was said in this capacity, Rabbi Ishak was able to influence the Caliph's treatment of the Jews. In addition to his astronomical studies, he was head of a Talmud Tora, as well as author of a Talmudic commentary, now lost. Several of Rabbi Ishak's rulings are cited in the writings of Moshe ben Maimon (Maimonides). Albalia's son, Barukh Ben Ishak Albalia left Seville and became a student in Lucena under Rabbi Ishak Alfassi (the RIF).
In twelfth century Barcelona lived Rabbi Avraham bar Hiyya ha-Nasi, a celebrated Jewish mathematician, astronomer, and philosopher. His written works, many which only fragments have been found, include Form of the Earth, an astronomical work on the formation of the heavens and the earth, which was to have been followed by a second part on the course of the stars. As sequels to the proceeding work, he wrote Calculation of the Courses of the Stars, and Tables of the Prince, (astronomical tables). The latter was also known as Tables of Al-Battani, because Avraham followed the Muslim astronomer of the same name during this period.
Yehudah ben Shelomo ha-Kohen ibn Malkah was a Spanish philosopher, astronomer, and mathematician. Born in Toledo roughly around 1215, he was a pupil of Meir Abulafia, an anti-Maimonist. Ibn Malkah was greatly interested in mysticism. He wrote: "He who wishes to know the Divine wisdom [kabala] must first know mathematical science [which includes astronomy], and then the Divine wisdom will repose in his heart." So wise, while a youth of eighteen, ibn Malkah corresponded with Johannes Palermitanus and Theodorus of Antioch, philosophers of the Roman Empire. Emperor Frederick II consulted ibn Malkah about scientific matters, and his answers proved so acceptable that he was invited to move to Roman Tuscany in the mid 13th century.
Maimonides was very interested in studying the newly translated Greek texts. In regards to astronomy, he wrote, "Physics and astronomy teaches us how God moves the world." In his well known Guide, Maimonides talks of attempts made in Spain to find a more adequate explanation of the solar system. However, he also writes how he believes earlier ideas, such as Aristotle's, ideas that say astronomy is, "Analogous to guessing and conjecture." Maimonides wrote an essay on the Jewish calendar based on astronomical principles. The calendar is divided into two parts, on the conjunction of the moon, and on the seasons of the year. He was the first to combine astronomy and halakha in regarding complicated calculations to determine visibility of the new moon.
Rabbi Avraham ben Yom-Tov of Jerusalem became astronomer and rabbi of Constantinople. He was born about 1480, and was a pupil of Eliyahu Mizrahi. Maran Yossef Karo is quoted calling Yom-Tov a, "high authority." He is best remembered for editing a calendar for the Jewish, Christian, and Muslim years which was printed in 1526 at Constantinople. They claimed this calendar was so accurate it was verified by the means of an instrument. Yom-Tov cited the Egyptian born physician, philosopher and astronomer, Ishak ben Shelomo Israeli (known as Ishak Israeli the Elder). Israeli was born in Egypt before 832 and died in 932 in what is modern day Tunisia. A contemporary of Saadia Gaon, he was said to understand all the seven sciences.
Born centuries later, but with the same name, was Ishak ben Shelomo Israeli (known as Ishak the Younger). This Ishak was a 14th century Spanish astronomer from the large Jewish community of Toledo. He comprised many works on astronomy, but his work Yesod Olam (The Foundation of the World), was considered one of the best contributions on astronomy to Hebrew literature. This work included the study of the structure and position of the globe, of the number and movements of the celestial spheres (stars, moons, etc.). It also covered the time differences in days and nights over various parts of the earth. Ishak's work also included data on the movements of sun and moon, of the solstices, and eclipses.
Abba Mari Halfon was an Italian astronomer of the fifteenth and sixteenth centuries. In 1492 he studied at Naples. Halfon translated Arabic astronomical material into Hebrew, as well as wrote a commentary on the earlier Alfonsine Tables that contained the positions and movements of the planet.
…Part II will be published in 2 weeks.
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