In 2013, Al-Jallad used the Safaitic database as he worked on an inscription containing several mysterious words: Maleh, Dhakar, and Amet. Earlier scholars had assumed that they were the names of unknown places. Al-Jallad, unconvinced, searched the database and discovered another inscription that contained all three. Both inscriptions discussed migrations in search of water, and a possibility occurred to him: if the words referred to seasons of migration, then they might be the names of constellations visible at those times.

Al-Jallad began pulling up every inscription that mentioned migrating in search of rain, and soon he had a long list of terms that had resisted translation. Comparing them with the Greek, Aramaic, and Babylonian zodiacs, he started making connections. Dhakar matched up nicely with dikra, the Aramaic word for Aries, and Amet was derived from an Arabic verb meaning “to measure or compute quantity”—a good bet for the scales of Libra. Hunting for Capricorn, the goat-fish constellation, Al-Jallad found the word ya’mur in Edward Lane’s “Arabic-English Lexicon,” whose translation read, “A certain beast of the sea, or . . . a kind of mountain-goat.” He stayed up all night, sifting the database and checking words against dictionaries of ancient Semitic languages. By morning, he had deciphered a complete, previously unknown Arabian zodiac. “We’d thought that they were place names, and, in a way, they were,” he told me. “They were places in the sky.”

These are theconstellations you will see in the direction of the Sun on the horizonafter sunset or before sunrise.