Lost & Found This 1,000-Year-Old Smartphone Just Dialed In By Franz Lidz and Clara Vannucci

For 2,000 years, celestial observers mapped the heavens with astonishingly precise instruments called astrolabes.

Resembling large, old-fashioned vest pocket watches, astrolabes allowed users to determine time, distances, heights, latitudes and even (with a horoscope) the future.

Recently, an astrolabe dating to the 11th century turned up at the Fondazione Museo Miniscalchi-Erizzo in Verona, Italy.

Federica Gigante, a historian at the University of Cambridge, first noticed it in a corner of a photograph while searching online for an image of a 17th-century collector whose miscellany was housed in the museum.

After learning that the museum staff had very little information about the piece, Dr. Gigante went to Verona for a closer look.

At the museum, a curator brought her to a side room, where she stood by a window and watched the sunlight illuminate the relic’s brass features.

She made out Arabic inscriptions and, seemingly everywhere, faint Hebrew markings, Western numerals and scratches that looked like they had been keyed.

“In the raking light, I realized that this wasn’t just an incredibly rare, ancient object but a powerful record of scientific exchange between Muslims, Jews and Christians over nearly a millennium,” Dr. Gigante said.

Astrolabes are believed to have been around at the time of Apollonius of Perga, a Greek mathematician from the third-century B.C. known as the Great Geometer.

Islamic scholars improved the gadgets, and by the ninth century A.D. the Persians were using astrolabes to locate Mecca and ascertain the five periods of prayer required each day, as stated in the Quran.

The tool reached Europe through the Moorish conquest of much of Spain.

By analyzing the Verona astrolabe’s design, construction and calligraphy, Dr. Gigante narrowed its provenance to 11th century Andalusia, where Muslims, Jews and Christians had worked alongside one another, particularly in the pursuit of science.

“As the astrolabe changed hands, it underwent numerous modifications, additions and adaptations,” Dr. Gigante said.

The original Arabic names of the signs of the zodiac were translated into Hebrew, a detail that suggested that the relic had at one point circulated within a Sephardi Jewish community.

One side of a plate was engraved in Arabic with the phrase “for the latitude of Cordoba, 38° 30’”; on the other side “for the latitude of Toledo, 40°.”

A handful of latitude values were corrected, some multiple times. Another plate was etched with North African latitudes which indicated that, during the instrument’s travels, it might have been used in Morocco or Egypt.

A series of Hebrew additions led Dr. Gigante to conclude that the astrolabe had eventually reached the Jewish diaspora in Italy, where Hebrew, rather than Arabic, was used.

“Basically, carving in the revisions was like adding apps to your smartphone,” Dr. Gigante said.