Greek Mythology and Planet Names
Why Planets Are Named After Gods
Mercury, Venus, Mars, Jupiter — every planet name traces back to Greek and Roman mythology. Here's the story behind each one.
The Complete Guide
Greek mythology features hundreds of named figures — each with their own stories, symbols, and significance. This comprehensive guide organizes every major figure for quick reference, whether you're studying for a class, writing a paper, or simply exploring the myths.
The Major Figures
At the top of the mythological hierarchy sit the twelve Olympian gods, who ruled from Mount Olympus after overthrowing the Titans. Below them are the minor gods, primordial deities, Titans, heroes, and the countless nymphs, spirits, and monsters that populated the ancient Greek imagination.
Origins and Genealogy
Nearly every figure in Greek mythology can trace their lineage back to the primordial beings — Chaos, Gaia, and Uranus. Understanding these family connections is essential to understanding why certain gods allied with or against each other, and why specific heroes were destined for greatness or tragedy.
Symbols and Domains
Each deity and mythological figure is associated with specific symbols, animals, plants, and domains of influence. These symbols were not merely decorative — they represented the fundamental powers and responsibilities of each figure, and were used in worship, art, and storytelling throughout the ancient world.
Cultural Significance
These figures were not merely characters in stories — they were the foundation of ancient Greek religion, philosophy, and identity. Temples were built in their honor, festivals celebrated their deeds, and their names were invoked in everything from marriage ceremonies to battle cries. Understanding these figures means understanding the civilization that gave birth to Western culture.
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From Babylonian Stars to Roman Gods
The custom of linking each wandering star to a god is older than Greece. Babylonian astronomers associated the visible planets with their own deities: the bright morning and evening star with Ishtar, goddess of love and war; the red planet with Nergal, a god of plague and the underworld; the brilliant slow planet with Marduk, king of the gods. Greek writers of the fourth century BC took over the scheme and substituted their own gods, a borrowing that the Platonic dialogue Epinomis openly credits to "Syrian" and Egyptian star-watchers.
Before that, the Greeks had descriptive names. Homer and Hesiod know the morning star as Eosphoros or Phosphoros, "bringer of dawn" or "bringer of light," and the evening star as Hesperos; the discovery that they were the same body was attributed to Pythagoras or Parmenides. Hellenistic astronomers also used names that described each planet's look: Stilbon, "the twinkling one," for Mercury; Pyroeis, "the fiery," for Mars; Phaethon, "the shining," for Jupiter; and Phainon, "the appearing" or "shining," for Saturn. Alongside these ran the theophoric names: the star of Hermes, of Aphrodite, of Ares, of Zeus and of Cronus. The Romans translated the divine names directly, and it is their versions that have come down to us.
The Planets One by One
- Mercury (Greek Hermes). The fastest-moving planet across the sky was naturally given to the messenger god Hermes, who travelled between Olympus, earth and the Underworld.
- Venus (Aphrodite). The brightest object in the sky after the Sun and Moon, beautiful at dawn and dusk, went to Aphrodite, matching the Babylonian Ishtar.
- Earth. The only planet whose English name is not mythological; it comes from Old English. The Greek personification of the earth is Gaia.
- Mars (Ares). Its blood-red colour made it the planet of the war god Ares. When Asaph Hall discovered its two small moons in 1877, they were named Phobos ("fear") and Deimos ("terror") after the sons of Ares, following Iliad Book 15, where Ares orders them to yoke his horses. See Phobos and Deimos.
- Jupiter (Zeus). The largest planet carries the name of the king of the gods. Its four big moons, discovered by Galileo in 1610, were named Io, Europa, Ganymede and Callisto by Simon Marius on a suggestion from Kepler: all four are lovers of Zeus. Galileo himself had called them the Medicean Stars. See the lovers of Zeus.
- Saturn (Cronus). The slowest of the planets known to the ancients was given to the old ruler Cronus, Zeus' father. Many of its moons are named after Titans and their kin: Titan, Rhea, Iapetus, Hyperion, Tethys, Phoebe and Dione, along with Enceladus and Mimas, two of the Giants.
- Uranus (Ouranos). William Herschel, who discovered it in 1781, wanted to call it Georgium Sidus after King George III. Johann Bode proposed Uranus, the Latinised Greek sky god and father of Cronus, completing a sequence of grandfather, father and son. It is the only major planet named directly after a Greek rather than a Roman god. Its moons break the pattern and are named after characters from Shakespeare and Alexander Pope. See Uranus.
- Neptune (Poseidon). Found in 1846 after Urbain Le Verrier predicted its position and Johann Galle observed it, it received the name of the Roman sea god. Its largest moon is Triton, the son of Poseidon, and others include Nereid and Proteus.
- Pluto (Hades). Discovered by Clyde Tombaugh in 1930, it was named after a suggestion by Venetia Burney, an eleven-year-old girl in Oxford. Pluto, Latinised from the Greek Plouton, was a common name for Hades. It was reclassified as a dwarf planet in 2006. Its moons continue the Underworld theme: Charon, Styx, Nix (Nyx), Hydra and Kerberos.
Dwarf Planets and Asteroids
The body whose discovery prompted Pluto's demotion was named Eris in 2006, after the goddess of strife, a pointed choice given the dispute it caused among astronomers; its moon is Dysnomia, "lawlessness," a daughter of Eris in Hesiod. See Eris. Ceres, the largest object in the asteroid belt, is the Roman goddess equated with Demeter. Many asteroids carry mythological names too, including Pallas, Juno and Vesta among the first four found, and the Trojan asteroids that share Jupiter's orbit, named after heroes of the Trojan War, with Greeks in one group and Trojans in the other.
Ancient sources
- Plato (attributed), Epinomis — names the planets as stars of Aphrodite, Hermes, Zeus, Cronus and Ares, and says the practice came from foreign astronomers.
- Hesiod, Theogony 381 — names Eosphoros, the morning star, as a child of Eos, and elsewhere sets out the descent from Ouranos to Cronus to Zeus that the outer planets now follow.
- Homer, Iliad 15.119–120 — Ares commands Deimos and Phobos to yoke his horses, the passage behind the names of Mars' moons.
- Homer, Iliad 22.317–318 — compares the point of Achilles' spear to Hesperos, "the most beautiful star in the sky."
- Cicero, On the Nature of the Gods Book 2 — lists the five planets with their Greek and Latin names and describes their motions.
Frequently asked questions
Which planet is named after a Greek god rather than a Roman one?
Uranus. All the other planets beyond Earth carry Roman names, although each Roman god was identified with a Greek counterpart.
Why is Mars named after the god of war?
Its reddish colour suggested blood and fire. The Babylonians linked it to Nergal, a god of destruction, and the Greeks and Romans to Ares and Mars.
Who named Pluto?
Venetia Burney, an eleven-year-old schoolgirl in Oxford, suggested the name in 1930. Lowell Observatory staff chose it partly because its first two letters matched the initials of Percival Lowell, who had searched for the planet.
What did the ancient Greeks call the planets?
They used descriptive names such as Phosphoros and Hesperos for Venus, Pyroeis for Mars and Phainon for Saturn, and later the names of gods: the star of Hermes, Aphrodite, Ares, Zeus and Cronus.