Greek Mythology and the Zodiac Signs – Origins and Myths

Where the star stories were written down

The twelve signs did not arrive in Greece with their myths attached. The constellations of the ecliptic were largely mapped in Mesopotamia, where the Bull, the Twins, the Lion, the Scorpion and the Goat-Fish already existed, and the twelve equal divisions of the zodiac were a Babylonian innovation of the later first millennium BC. The Greeks supplied the stories. The key texts are Aratus' Phaenomena, a third-century BC poem describing the sky; the Catasterisms attributed to Eratosthenes, a handbook explaining how each figure got there; and Hyginus' Latin De Astronomia, which often records two or three competing explanations. Reading them side by side shows that most signs had no single official myth.

Signs with more than one story

Taurus. Eratosthenes identifies the bull with Zeus's disguise for Europa's abduction, but mentions an alternative in which it is Io turned into a cow. Only the front half of the animal appears in the sky, which ancient writers explained by saying the rest was hidden in the sea as it swam.

Leo. The Nemean lion is the usual answer, and Eratosthenes says Zeus honoured it because the lion is king of beasts.

Virgo. Aratus tells the most developed story. The maiden is Dike, Justice, who lived openly among humans in the Golden Age, withdrew to the hills in the Silver Age, and fled to the sky when the Bronze Age forged the first swords. Hyginus adds other candidates: Erigone, daughter of Icarius, who hanged herself after finding her father murdered, and Parthenos, a daughter of Apollo. The Demeter identification rests mostly on the ear of grain the figure holds, the star Spica.

Libra. For most of Greek astronomy this sign did not exist as scales at all. Its stars were the Chelai, the Claws of the Scorpion. In the late Hellenistic and Roman period they were reimagined as Libra, the Scales, which became the standard sign. That is why the scale-bearing figures of Themis and Astraea are attached to it only loosely.

Sagittarius. The centaur-archer is often called Chiron, but Eratosthenes says this is a mistake: Chiron is the separate constellation Centaurus, and centaurs did not use bows. His archer is Crotus, son of Eupheme, the nurse of the Muses, credited with inventing archery and leading the applause for their songs. Hyginus reports both identifications.

Capricorn. In Eratosthenes, the goat-fish is Aegipan, foster-brother of Zeus, honoured for helping in the war against the Titans, partly by blowing a conch shell that panicked them. The story of Pan diving into the Nile as Typhon approached is found in Hyginus. Typhon's attack also explains Pisces: Ovid's Fasti has Venus and Cupid flee into the Euphrates and turn into fish to escape.

Aquarius. Ganymede is the common answer, but Hyginus also mentions Deucalion, survivor of the great flood, and Cecrops, the early king of Athens, as rival claimants.

Gemini, Scorpio and the logic of placement

Several myths explain how the stars move. In Aratus, the hunter Orion sets in the west as the Scorpion rises in the east, as if still fleeing; the scorpion was sent by Artemis after Orion tried to assault her, one of several reasons offered for his death. The arrangement Pindar describes for the Dioscuri, in Nemean 10, is a shared fate rather than an astronomical fact: Polydeuces chooses to divide his immortality with Castor, so that both spend alternate days beneath the earth and on Olympus. Later writers mapped that story onto the twin stars Castor and Pollux.

What the dates do not tell you

The sign dates printed in horoscopes were fixed by Hellenistic astrologers, codified by Ptolemy in the second century AD, and tied to the equinoxes rather than to the stars. Because the Earth's axis slowly precesses, the sun now passes through each constellation about a month later than the sign dates suggest; on 21 March it stands in Pisces, not Aries. The sun also crosses Ophiuchus, the Serpent-Bearer, often identified with Asclepius, which was never counted as a sign because the zodiac was conceived as twelve equal sectors. For the wider sky, see the constellation myths.

Ancient sources

• Aratus, Phaenomena — poetic description of the constellations, including the Golden Age story of Dike as the Maiden and Orion fleeing the rising Scorpion.
• Pseudo-Eratosthenes, Catasterisms — the standard catalogue of star myths; gives the bull of Europa, Crotus as the archer and Aegipan as Capricorn.
• Hyginus, De Astronomia — Latin handbook that records multiple variants per sign, such as Erigone for Virgo and Deucalion for Aquarius.
• Ovid, Fasti — explains several constellations by the calendar, including Venus and Cupid as the fish of Pisces.
• Pindar, Nemean 10 — the choice of Polydeuces to share his immortality with Castor.
• Ptolemy, Tetrabiblos — the systematic astrological treatment of the signs that later horoscopes descend from.

Frequently asked questions

Did the ancient Greeks invent the zodiac?

No. The constellations and the twelve-part division came from Babylonian astronomy. The Greeks adopted the system, added mythological explanations and developed horoscopic astrology in the Hellenistic period.

Is Sagittarius Chiron?

Ancient authors disagreed. Many later writers say so, but the Catasterisms assign Chiron to the constellation Centaurus and make Sagittarius the satyr-like archer Crotus.

Why is Libra the only sign that is an object?

Because it began as part of Scorpio. The Greeks called those stars the Scorpion's Claws, and the Romans later reinterpreted them as a pair of scales.

What is the 13th zodiac sign?

People usually mean Ophiuchus, which the sun crosses between Scorpius and Sagittarius. It was never part of the twelve-sign system, which divides the ecliptic into equal sectors regardless of the size of the constellations.