Ancient Astrolabe Uncovered in Groundbreaking Discovery of Islamic-Jewish Scientific Collaboration

In Verona, Italy, a scientist has uncovered an eleventh-century Islamic astrolabe, a distinctive artifact featuring both Arabic and Hebrew inscriptions. This discovery highlights the extensive scientific co-operation prevalent among Jewish, Christian, and Muslim cultures during the medieval era. The astrolabe serves as a tangible representation of intercultural exchange and widespread knowledge. Picture credit goes to Federica Gigante.

This particularly Islamic astrolabe dating back to the eleventh century is a rare discovery. Inscribed in both Arabic and Hebrew, this item ranks amongst the oldest and most unique examples ever unearthed. This celestial instrument underwent adaptations, translations and corrections for centuries across Spain, North Africa and Italy, benefiting Muslim, Jewish, and Christian users alike.

Dr. Federica Gigante serves on the History Faculty at Cambridge University and was responsible for unravelling this discovery at a museum in Verona, Italy. These findings came to light in the Nuncius Journal, having been published there.

Dr. Gigante first encountered a freshly uploaded image of the astrolabe on the website of the Fondazione Museo Miniscalchi-Erizzo. Intrigued by the image, she reached out to the institution to learn more.

“The museum was unaware of its value,” Dr. Gigante elaborated. “It has now become the most prized item in their collection.”

“As I observed the astrolabe more closely during my museum visit, I noted the detailed Arabic inscriptions that adorned it. However, I was also capable of identifying faint Hebrew inscriptions. These inscriptions were only visible as the sunlight hit them through a window. Despite my disbelief and astonishment, I kept identifying more and more such inscriptions. It was indeed an exhilarating moment.”

A close-up of the Verona astrolabe illustrates Hebrew inscribed primarily, positioned above Arabic inscriptions. Picture credit goes to Federica Gigante.

“This object is not merely rare; it portrays an intriguing record that documents the scientific exchange between Muslims, Jews, and Christians over centuries,” said Dr. Gigante.

“The Verona astrolabe experienced numerous modifications and alterations as it passed hands. At least three different users felt compelled to contribute translations and improvements to this instrument, with two using Hebrew and one resorting to a Western language.”

Astrolabes are known as the pioneer of smartphones. These portable technological marvels were used for hundreds of purposes. This two-dimensional model of the universe fit the palm of one's hand, aiding individuals in calculating the time, distances, constellations, and even predicting the future with horoscope casting.

Dr. Gigante, a renowned expert on Islamic astrolabes and former curator of Islamic scientific instruments, assigned a location and date to the 'Verona astrolabe' after an extensive analysis of scientific, design, construction and calligraphic features. She tracked down the artifact's origin to Andalusia, matching its construction and engraving style along with scales on the back to astrolabes made in Al-Andalus, a region under Muslim rule in Spain, during the eleventh century.

An inscription in Arabic denotes “the latitude of Cordoba, 38° 30′" on one side of the plate, and "for the latitude of Toledo, 40°,” on the other side, suggesting that the astrolabe could have been manufactured in Toledo when it was a thriving center of cultural exchange among Muslims, Jews, and Christians.

The presence of Muslim prayer timelines and prayer names on the astrolabe facilitated the original users to adhere to their daily prayer schedules.

A close-up of the Verona astrolabe shows Hebrew, Arabic, and Western Numerals inscriptions. Picture credit goes to Federica Gigante.

An inscription marks the astrolabe with the phrase “for Isḥāq […]/the work of Yūnus." This could have been engraved sometime after the creation of the astrolabe possibly for a subsequent owner.

The two Arabic names, Isḥāq and Yūnus, could be indicative of Jewish names scripted in Arabic, revealing that the artifact might have been passed around a Sephardi Jewish community in Spain, Arabic being the colloquial language.

An additional plate inscribed with the typical latitudes of North Africa hints that the artifact could have been used in Morocco or Egypt at some point.

Hebrew inscriptions were added by more than one individual with variations in depth and neatness, suggesting changes in the hands responsible for the inscribing.

Dr. Gigante claimed, “The Hebrew additions and translations imply that the artifact eventually left Spain or North Africa to reside amongst the Jewish diaspora community in Italy where Arabic was unspoken, and Hebrew was the preferred language.”

Unusually, one of the Hebrew additions, engraved neatly above the Arabic marking for latitude 35°, reads “34 and a half” rather than “34 ½,” which suggests that the engraver was not an astronomer or astrolabe maker.

Other Hebrew inscriptions are instead translations of the Arabic names for astrological signs, for Scorpio, Sagittarius, Capricorn, Aquarius, Pisces, and Aries.

Dr. Gigante points out that these translations reflect the recommendations prescribed by the Spanish Jewish polymath Abraham Ibn Ezra (1089–1167) in the earliest surviving treatise on the astrolabe in the Hebrew language written in 1146 in Verona, exactly where the astrolabe is found today.

Twelfth-century Verona hosted one of the longest-standing and most important Jewish communities in Italy. Ibn Ezra’s treatise assumes pre-existing knowledge of the astrolabe among the Verona Jewish community, showing that the instrument must already have been popular.

Ibn Ezra’s description has a lot in common with the ‘Verona astrolabe’ which would have been in circulation by the time Ibn Ezra was in Verona. He warned his readers that an instrument must be checked before use to verify the accuracy of the values to be calculated.

Dr. Gigante suggests that the person who added the Hebrew inscriptions might have been following such recommendations.

The astrolabe features corrections inscribed not only in Hebrew but also in Western numerals, the same we use in English today.

All sides of the astrolabe’s plates feature lightly scratched markings in Western numerals, translating and correcting the latitude values, some even multiple times. Dr. Gigante thinks it is highly likely that these additions were made in Verona for a Latin or Italian language speaker.

In one case, someone lightly scratched the numbers “42” and “40” near the inscription reading “for the latitude of Medinaceli, 41° 30′.”

Dr. Gigante said: “Not only do both numerals differ from the value given in the Arabic, they don’t agree between themselves. It may be that a later user of the instrument thought the original Arabic value was wrong and amended it. But the correct, modern value for the latitude of Medinaceli is 41°15′, indicating that the Arabic value was more accurate than either amendment.”

Elsewhere on the instrument, Gigante found similar conflicting and erroneous amendments relating to the latitudes of Cordoba and Toledo.

The astrolabe features a ‘rete’ – a pierced disk representing a map of the sky – which is one of the earliest known made in Spain. Remarkably, it features similarities with the rete of the only surviving Byzantine astrolabe made in AD1062 as well as with those of the earliest European astrolabes, made in Spain on the model of Islamic ones.

A calculation of the star’s position allows a rough timing of the sky for which it was created. Dr. Gigante explains that “due to a phenomenon called the precession of the equinoxes, whereby the earth rotates on its axis not in a straight line, but in a “wobbly” manner, like a spinning top about to stop, the stars’ apparent positions above our heads change constantly, about 1 degree every 70 years.”

By analyzing the position of the stars on the rete, it is possible to calculate that they were placed in the position that stars had in the late 11th century, and that they match those of other astrolabes made, for example, in AD 1068.

The astrolabe is thought to have made its way into the collection of the Veronese nobleman Ludovico Moscardo (1611–81) before passing by marriage to the Miniscalchi family. In 1990, the family founded the Fondazione Museo Miniscalchi-Erizzo to preserve the collections.

“This object is Islamic, Jewish, and European, they can’t be separated,” Dr. Gigante said.