How Moons Get Their Names: From Mythology to Scientists

1. The Origins of Lunar Names: From Gods to Giants

Before telescopes, Earth’s Moon was the only one we knew. Across civilizations, it inspired countless myths and deities—Selene and Artemis in Greek mythology, Luna and Diana in Roman tales, Chandra in Hindu tradition, and Tsukuyomi in Japanese lore. These early names, though mythological, reflected human attempts to understand nature through stories.

When Galileo Galilei first observed Jupiter through a telescope in 1610, he saw four bright points orbiting the giant planet—now known as the Galilean Moons: Io, Europa, Ganymede, and Callisto. These names, chosen by astronomer Simon Marius shortly after Galileo’s discovery, came from the mythological lovers and companions of Zeus (the Greek counterpart of Jupiter). This mythological naming set a precedent that still guides how moons are named today.

2. The Role of the International Astronomical Union (IAU)

Founded in 1919, the International Astronomical Union became the official arbiter of celestial naming conventions. Before its establishment, astronomers often used personal or regional names for discoveries, which caused confusion. The IAU standardized the process to maintain scientific order and global consistency. Under IAU rules, the discoverer of a moon typically has the right to propose a name, but it must align with certain conventions tied to the planet it orbits. Once proposed, a name goes through several layers of review by committees specializing in planetary nomenclature. Only after approval does it become official and recognized internationally. For example, all of Jupiter’s moons are named after mythological figures associated with Zeus/Jupiter. Saturn’s moons honor Titans and figures from Roman or Greek mythology. Uranus’ moons, uniquely, draw from the works of William Shakespeare and Alexander Pope. This creates a cosmic tapestry that’s both organized and rich with cultural meaning.

3. A Tradition of Mythology: Jupiter and Saturn’s Families

Jupiter’s Mythological Entourage

Jupiter, the king of the gods, has the largest collection of moons—currently over 90 confirmed. Many follow the theme of mythological figures associated with Zeus, such as his lovers, descendants, and attendants. Io, for example, was a priestess transformed into a cow to hide her from Hera’s jealousy. Europa, a Phoenician princess, was abducted by Zeus in the form of a bull. Ganymede, the largest moon in the Solar System, was a handsome youth brought to Olympus as cupbearer to the gods. Callisto, another favorite of Zeus, was transformed into a bear and placed among the stars.

As new moons were discovered with modern telescopes and spacecraft like Galileo and Juno, their names continued this mythological trend. Recent examples include Philophrosyne and Eirene, named after Greek goddesses representing kindness and peace, respectively. The tradition blends the ancient with the scientific—a bridge between myth and measurement.

Saturn’s Titan Lineage

Saturn, named after the Roman god of time and harvest, follows a similar mythic pattern. Its moons often bear the names of Titans, giants, and other divine figures from Greco-Roman lore. Titan, discovered by Christiaan Huygens in 1655, is the most famous and massive—appropriately sharing its name with the legendary race of primordial deities. Other examples include Rhea, Dione, Tethys, and Hyperion, all named after Titan gods or their descendants.

However, as exploration extended through spacecraft missions like Cassini, astronomers began including mythologies beyond the Greco-Roman world. Moons discovered in the 20th and 21st centuries—such as Skoll, Surtur, and Fenrir—take their names from Norse mythology, reflecting Saturn’s association with diverse mythic traditions. This inclusivity underscores the IAU’s aim to represent humanity’s shared heritage in the cosmos.

4. The Literary Legacy of Uranus’ Moons

Uranus stands apart in its naming conventions. Rather than drawing from mythology, its moons honor the imaginative world of literature. The first two moons, Oberon and Titania, were discovered by William Herschel’s son John in 1787 and named after the fairy king and queen from Shakespeare’s A Midsummer Night’s Dream. Later moons continued this Shakespearean theme, adding characters like Miranda, Ariel, Umbriel, and Puck—figures drawn from both Shakespeare and Alexander Pope’s The Rape of the Lock.

This literary naming tradition reflects the Enlightenment era’s fascination with art and intellect. Uranus itself was named after the Greek god of the sky, Ouranos, symbolizing a celestial link between heaven and human creativity. Today, each new Uranian moon discovered through telescopes or space missions must bear a name from Shakespeare or Pope, creating one of the most poetic naming systems in astronomy.

5. Neptune and Pluto: Cold Worlds, Rich Stories

Neptune’s Oceanic Inspiration

Discovered in 1846, Neptune carries the name of the Roman god of the sea, and fittingly, its moons follow an aquatic theme drawn from Greek and Roman mythology. The largest, Triton, discovered just 17 days after Neptune itself, is named after Poseidon’s son and messenger of the sea. Later discoveries like Nereid, Proteus, Galatea, and Thalassa continue this pattern, each evoking water deities or sea spirits.

Smaller moons discovered by the Voyager 2 spacecraft and later by the Hubble Space Telescope—such as Halimede, Naiad, and Hippocamp—reflect this oceanic lineage. The naming beautifully ties Neptune’s distant, deep-blue appearance to mythic seas of imagination.

Pluto’s Underworld Companions

When Pluto was discovered in 1930, it was named after the Roman god of the underworld—a fitting moniker for the Solar System’s dim, distant frontier. Although Pluto was reclassified as a dwarf planet in 2006, its moons retain mythological resonance. Charon, discovered in 1978, is named after the ferryman who carried souls across the River Styx. Nix, Hydra, Kerberos, and Styx all draw from Greek underworld mythology, representing the spirits, guardians, and rivers of the dead. This consistent thematic approach—linking Pluto’s cold, shadowy realm with the myths of the afterlife—creates one of the most cohesive naming systems in planetary science. Even after Pluto’s demotion from full planetary status, its mythic identity endures through its moons.

6. Beyond the Giants: Small Worlds, Big Names

Not all moons belong to the Solar System’s giants. Smaller planets and even asteroids have their own satellites, and these too receive carefully chosen names. Mars has two moons, Phobos and Deimos, named by astronomer Asaph Hall in 1877 after the Greek gods of fear and terror—fitting for the god of war. Eris, the dwarf planet discovered in 2005, has one moon, Dysnomia, named after the daughter of the goddess Eris, symbolizing lawlessness.

Even asteroids like Ida and Dactyl follow mythological roots. Dactyl, discovered orbiting Ida in 1993, was named after the mythic “Dactyls,” magical beings who lived on Mount Ida. The use of mythology for small moons maintains consistency and poetic continuity, connecting even the tiniest celestial bodies to humanity’s oldest tales.

7. The Science Behind the Names: Catalog Numbers and Designations

Before a moon earns its official name, it starts with a provisional scientific designation. This name follows a precise formula: the letter “S” (for satellite), followed by the year of discovery and a sequential number. For example, S/2003 J 19 means it’s the 19th satellite discovered orbiting Jupiter in 2003. This designation remains until the IAU formally approves a name. It ensures that even without a poetic title, every moon can be scientifically tracked and referenced. Once confirmed, the moon’s name is added to official astronomical catalogs, used in research papers, and integrated into mission planning. This process ensures both scientific accuracy and cultural richness coexist in celestial nomenclature.

8. When Names Reflect More Than Myth: Modern Honorees

While mythology dominates lunar naming, there are exceptions. Occasionally, modern scientists, explorers, or cultural figures inspire names—especially for minor moons or features on their surfaces. For instance, the New Horizons mission team informally named regions on Pluto and Charon after legendary explorers, fictional characters, and spacecraft. Although not all such names are officially recognized, they reflect the human desire to personalize discovery.

Some small moons orbiting asteroids or dwarf planets are also named after contributors to astronomy. This blend of ancient myth and modern honor creates a living record of exploration, where history and science meet.

9. Cross-Cultural Naming: Expanding Beyond the Western Lens

The IAU increasingly recognizes that space belongs to all humanity, not just to cultures of Greco-Roman origin. As new moons are discovered, astronomers often draw from global mythologies—including Norse, Inuit, Polynesian, and Japanese traditions. For instance, Saturn’s moon Skathi comes from Norse myth, named after a giantess associated with skiing and mountains. Pluto’s moon Kerberos uses the Greek spelling rather than the Roman “Cerberus,” honoring global linguistic diversity. Some future naming conventions may include figures from African, Mesoamerican, or Indigenous cosmologies, broadening the cultural reach of astronomy. This inclusive trend not only diversifies the night sky but also emphasizes that the wonder of exploration transcends cultural boundaries. Each name becomes a cultural bridge, carrying stories from Earth to the stars.

10. How New Moons Are Named Today: The Step-by-Step Process

The discovery of a new moon sets in motion a fascinating blend of science and storytelling. Here’s how it works:

When astronomers detect a potential moon—often through telescopic imaging or spacecraft data—they submit their findings to the IAU’s Working Group for Planetary System Nomenclature (WGPSN). The discovery is verified through multiple observations to confirm the object’s orbit.

Once verified, the moon receives a temporary designation, like S/2023 J2. The discoverers then propose an official name following the planet’s thematic rules. For instance, if it’s a Jovian moon, the name must come from Greek or Roman mythology connected to Zeus/Jupiter. If it orbits Uranus, it should be a character from Shakespeare or Pope. The proposal must also follow IAU guidelines—names must be 16 characters or fewer, pronounceable, non-offensive, and distinct from existing celestial names.

After review and public announcement, the IAU formally approves the name. It then becomes part of the permanent astronomical record—appearing in databases, textbooks, and mission charts. This careful process ensures that every moon, no matter how small, earns a name worthy of its place in the heavens.

11. Unnamed Moons: The Challenge of the Tiny and the Many

Not every moon is named right away. As of the 2020s, many small moons—especially around Jupiter and Saturn—still carry only their provisional designations. Some are irregular satellites, captured asteroids with distant or chaotic orbits. Because hundreds exist, astronomers prioritize naming the most prominent or scientifically interesting ones first.

However, there’s growing public interest in naming smaller moons through citizen participation. Occasionally, the IAU hosts public naming campaigns—inviting people worldwide to suggest names within approved mythological frameworks. For instance, the 2019 campaign to name five of Jupiter’s moons received thousands of submissions, leading to the adoption of names like Eirene and Pandia. These efforts connect the public directly to space exploration, blending science with global imagination.

12. Famous Naming Stories and Controversies

Even celestial naming has its share of drama. In the early 20th century, Neptune’s moon Nereid was almost named after a scientist rather than a mythic figure, which broke convention. Similarly, when Pluto was discovered, there was debate over whether to use the name of an underworld god or a scientific acronym (Percival Lowell’s initials, “PL”). Ultimately, “Pluto” won thanks to an 11-year-old English girl, Venetia Burney, whose suggestion perfectly fit the mythological and astronomical spirit. More recently, the IAU rejected names proposed outside its guidelines—such as pop culture references—to maintain scientific decorum. Yet, spacecraft teams still use informal nicknames during missions. For example, New Horizons informally dubbed one of Pluto’s regions “Cthulhu Macula,” after H.P. Lovecraft’s fictional creature. While not officially recognized, such names highlight the creative tension between scientific order and cultural enthusiasm.

13. Why Naming Matters: The Power of Story in Science

At first glance, naming might seem like a symbolic gesture, but it plays a crucial role in how humans relate to the universe. A name gives identity, meaning, and narrative to what would otherwise be a string of numbers and coordinates. It transforms a cold, distant object into something memorable—a bridge between discovery and understanding.

Names like Ganymede, Titan, or Charon evoke entire mythological worlds, reminding us that exploration isn’t just about data—it’s about connection. They allow scientists, students, and enthusiasts to talk about celestial bodies with familiarity and fascination. In this way, naming unites the precision of astronomy with the imagination of culture.

Moreover, naming reflects humanity’s shared quest for knowledge. Whether a moon is named after a Titan, a fairy queen, or a sea nymph, it carries echoes of our collective curiosity. Each new discovery adds a chapter to the story of how we see ourselves in the cosmos.

14. The Future of Lunar Naming: From Exomoons to AI Discoveries

As telescope technology and artificial intelligence advance, astronomers expect to find exomoons—moons orbiting planets beyond our Solar System. These discoveries will spark new discussions about naming conventions. Will the IAU extend mythological patterns, or will new systems emerge based on cultural, environmental, or scientific themes? AI-assisted discovery also raises new questions: if a computer algorithm identifies a moon, who gets naming rights—the programmer, the research team, or the institution? Such issues reflect the growing complexity of 21st-century astronomy, where human creativity meets machine precision. The future may even bring more democratic naming systems, with global votes or cultural partnerships to ensure representation from all parts of the world. What remains constant is the desire to tell stories through the stars—to link the distant with the familiar.

15. Naming the Night Sky

Every moon, from Earth’s Luna to Jupiter’s vast Ganymede, carries a story written across time. The naming of these celestial bodies isn’t random—it’s a testament to our imagination, our reverence for myth, and our scientific curiosity. The International Astronomical Union ensures that as our reach extends into the Solar System and beyond, each discovery receives a name that honors both its physical reality and the culture that found it.

When you next look up at the Moon, remember: every bright dot circling a distant planet also bears a name chosen with care—a blend of legend, literature, and logic. It’s how humanity keeps one foot on the Earth and one in the stars, ensuring that as we map the universe, we never lose our sense of wonder.