How to Name a Planet

Real planets get their names from a slow, bureaucratic, occasionally democratic process run by astronomers. Fictional planets get theirs from a novelist or a game studio deciding, in an afternoon, what a whole world should be called. Both processes are worth understanding if you're inventing one yourself, because the real system is more interesting than "scientists just pick something," and the fictional conventions that work best usually borrow more from real astronomy than they let on. This guide covers how actual planets and moons are named, how fiction builds on and departs from that system, and the practical rules for inventing a planet name that holds up.

How Real Planets Are Actually Named

The body responsible for official astronomical names is the International Astronomical Union, the same organization that in 2006 formally defined what counts as a planet at all. For exoplanets — planets orbiting stars other than the Sun — the IAU's working convention is a designation built from the host star's name plus a lowercase letter assigned in order of discovery, starting at "b." The star itself is treated as "A" implicitly and doesn't carry a letter. Kepler-452b, for instance, is the first confirmed planet discovered around the star Kepler-452; if a second planet turned up around that star, it would become Kepler-452c.

That system is deliberately unglamorous, because its job is to be unambiguous across a catalogue of thousands of confirmed exoplanets, not to sound evocative. Alongside it, the IAU has run public naming campaigns since 2015 under the name NameExoWorlds, inviting astronomy clubs, schools and the public to propose and vote on more memorable names for selected stars and their planets, which the IAU then formally approves. The catalogue designation never disappears — it stays the scientific reference — but a planet can carry a public name alongside it once a campaign names it.

Within our own solar system, planet names follow an older tradition: Roman gods, chosen well before any formal naming body existed, with Uranus as the one exception named for a Greek deity rather than a Roman one. Moons, dwarf planets, and smaller bodies are named by IAU working groups under their own conventions, and this is where the naming gets genuinely systematic — worth its own section, because it's the part fiction borrows from most often without necessarily crediting it.

Moons and the Mythological Naming Convention

Each planet's moons are named from a mythological set tied to that planet's own namesake, and the set is consistent rather than arbitrary. Jupiter's moons are named after lovers, companions and descendants of Zeus (Jupiter's Greek counterpart) — the four largest, discovered by Galileo, are Io, Europa, Ganymede and Callisto, all figures connected to Zeus in Greek myth. Saturn's moons draw on the Titans and their extended family, fitting Saturn's own identity as the Roman god equivalent to Cronus, father of the Olympians.

Uranus breaks the mythological pattern entirely and is the one planet whose moons are named after literary characters instead of gods — specifically, characters from the plays of William Shakespeare and Alexander Pope's poem "The Rape of the Lock." Titania and Oberon, the fairy king and queen from A Midsummer Night's Dream, and Miranda, from The Tempest, are among Uranus's major moons; Ariel and Umbriel come from Pope. Pluto's moons follow yet another logic tied to its own identity as the god of the underworld: Charon is named for the ferryman who carries souls across the river Styx, and the smaller moons Styx, Nix, Kerberos and Hydra are drawn from the same underworld mythology.

The pattern worth taking from all of this: real celestial naming isn't random even when it looks whimsical. Every name in a set traces back to one coherent source — one mythology, or in Uranus's singular case, one pair of authors — and that internal consistency is exactly what makes the system feel deliberate rather than decorative. It's a useful model for naming a fictional planet's moons, too: pick one source and draw every name in the set from it, rather than mixing mythologies freely.

Catalogue Designations, Settled Names, and Colonist Renaming

Fiction gets to do something real astronomy mostly doesn't: let the same planet carry more than one name at once, each one belonging to a different group of people and a different point in the planet's history. This is a strong worldbuilding device precisely because it mirrors how real places actually get renamed, and using all three layers on the same planet does real narrative work rather than just adding flavour text.

The catalogue designation is what a survey or scientific body calls the planet before anyone lives there — a string like the real Kepler-452b, or an invented equivalent like Sector 9 designations in a hard-SF setting. It's unglamorous on purpose, because it was assigned by an instrument or a bureaucracy with no interest in what the place means to anyone. The settled name is what the people who actually live there call it, once there's a "there" with a population — often shorter, often carrying meaning in the settlers' own language, and frequently unrelated to the catalogue string entirely. And colonist renaming is the layer that shows political change happening in real time: an empire renames a world it's conquered or annexed, a corporation renames a world it's bought the mineral rights to, or a liberated population discards an imposed name and reclaims an older one.

A single planet can plausibly carry all three at once, and which name a character uses tells the reader who that character is without a line of exposition. A company surveyor calls it by its catalogue string. A colonist born there calls it by the settled name, possibly without knowing the catalogue string exists. An occupying officer calls it by the imposed imperial name, and the choice to use that name in front of a local is itself a small act of aggression the scene doesn't need to explain. That's the actual payoff of building all three layers: you get characterisation for free, every time someone opens their mouth and picks which name to use.

How Naming Reveals Who Did the Naming

Every planet name in a story implies an author — not the writer, the in-world party who assigned it — and that party's identity leaks through the naming style whether you intend it or not. A survey corporation names planets like assets: alphanumeric, efficient, occasionally branded with the company's own name buried in the string. An empire names planets like territory: after emperors, conquests, or abstract virtues the regime wants associated with itself. The people who actually live there name their world the way real cultures name real places — after a geographic feature, an ancestor, a founding event, or simply "the ground" in their own language, because that's what a huge number of real-world place names literally mean when translated.

This gives you a fast diagnostic for any planet name you're inventing: before you finalize it, ask who assigned it and whether the name actually sounds like something that party would produce. A mining consortium wouldn't call a planet "Starhaven" any more than a mining company today names an asset after a feeling — check the catalogue names real space agencies actually use if you want the tone right. A society that's lived on a world for six generations wouldn't still be using the original survey designation as their everyday name for home, unless there's a specific in-world reason they haven't renamed it — which, if true, is itself worth a line of story.

Soft Rules for a Pronounceable Invented Planet Name

Planet names face a slightly different bar than character names, because a reader encounters them constantly but rarely has to say them in urgent dialogue. Even so, the basic pronounceability rules still apply, and they still get violated constantly in amateur worldbuilding.

• Anchor every consonant cluster with a nearby vowel. A name like "Vrzkhal" has no legal place to start pronouncing it; "Varzhal" keeps the harsh texture while giving a reader's mouth somewhere to begin.
• Cap most everyday names at two or three syllables. A capital city or a minor moon can afford a longer, more ceremonial name; a planet your characters say in casual dialogue every few pages benefits from staying short.
• Watch for accidental real words. An invented name that accidentally spells an ordinary English word, or a rude one in another language your readers might speak, undercuts the tone the moment someone notices — read the name aloud to someone else before you commit to it.
• Decide early whether it's Latin-flavoured or invented, and commit. A name built from real Latin roots (see the next section) and a name built from a wholly invented sound palette both work, but mixing the two within one name — one syllable that reads as genuine Latin next to one that reads as pure invention — tends to read as unintentional rather than deliberate.

Genre Conventions: Hard SF, Space Opera, and Grimdark

The genre you're writing in sets real expectations for how a planet name should sound, and working against those expectations without a reason tends to read as a mistake rather than a choice.

Hard SF leans toward catalogue-style names or names with a plausible scientific pedigree — a star's designation, a discoverer's name, a descriptive term drawn from the planet's actual properties. The genre's whole appeal rests on plausibility, so a planet called something as ornate as "Zephyrion Prime" sits oddly next to characters who otherwise talk like working astronauts. Space opera has more room for grandeur — names can be evocative, mythic, or simply beautiful-sounding, because the genre's contract with the reader already includes faster-than-light travel and galaxy-spanning empires, so a planet with a name that sounds designed rather than catalogued fits the tone. Coruscant and Trantor both belong here. Grimdark tends toward names that sound worn down, harsh, or bureaucratic-turned-brutal — a planet renamed by whichever empire currently occupies it, often stripped of whatever poetry the original name had, because that erasure is usually part of the genre's point.

Pitfalls to Avoid

A handful of mistakes show up constantly in invented planet names, and each one is avoidable once you know to check for it.

• Unpronounceable apostrophe clusters. An apostrophe that doesn't represent an actual sound — a glottal stop, a dropped syllable — is decoration, and readers notice the difference even when they can't say why a name feels unearned.
• Names that are just Latin words. "Terra Nova," "Ignis," "Aqua" — these read as placeholder names rather than invented ones, because any reader with a passing familiarity with Latin recognizes them instantly. They can work as a deliberate, transparent choice — a colony genuinely named by Latin-speaking founders — but used as if they were mysterious or alien, they undercut themselves.
• Planets named after their one biome. "Ice World," "Desert Planet," or a thinly veiled translation of the same idea, tells the reader the planet has exactly one environmental feature and nothing else worth mentioning. Real planets and moons have wildly varied terrain even within a single climate zone; a name that flattens a whole world down to one adjective usually signals that the worldbuilding stopped at the name.
• No distinction between who's speaking. If every character in the story uses the exact same name for a planet regardless of nationality, allegiance or history with the place, you've skipped the characterisation payoff described above for no real gain.

What Well-Known Fictional Planet Names Actually Derive From

A few well-documented examples, with how certain the derivation actually is — some are confirmed by the author, others are educated inference, and it's worth being honest about which is which.

The takeaway isn't that every great fictional planet name needs a traceable etymology — Arrakis and Trantor both work perfectly well without one. It's that the names which do carry a real derivation (Coruscant, Solaris, Hyperion) use it to reinforce the planet's identity rather than as a decorative flourish, which is the same principle behind the "who named it" section above: a name that means something, even a small something, tends to outlast one that's purely a pleasant sound.

FAQ

How are real exoplanets officially named?
By the host star's designation plus a lowercase letter assigned in order of discovery, starting at "b" — Kepler-452b is the first confirmed planet found around the star Kepler-452. The International Astronomical Union is the body that formally approves any name beyond that catalogue designation, including names proposed through its public NameExoWorlds campaigns.

Can the public actually name a planet?
Only through an official channel — the IAU's NameExoWorlds campaigns, which invite public and institutional proposals for specific selected stars and planets, with the IAU making the final approval. There's no way to purchase or informally register an official name for a star or planet through any private company; that kind of offering isn't recognized by the IAU.

Why do Uranus's moons have different names from every other planet's moons?
Every other planet's moons are named from a mythological tradition tied to that planet's own namesake. Uranus is the sole exception, with its moons named after characters from the plays of William Shakespeare and Alexander Pope's "The Rape of the Lock" instead of any mythological pantheon.

Should an invented planet name mean something?
It doesn't have to — plenty of memorable fictional planet names, like Arrakis and Trantor, have no confirmed derivation and work purely on sound. But a name that ties back to who named it, or to a real feature of the planet, tends to reward attentive readers and gives you material for later, so it's worth considering even when you ultimately choose a name for its sound alone.

What's the difference between a planet's catalogue name and its settled name?
A catalogue name is assigned by whoever surveyed or discovered the planet, before anyone lived there, and it's built for unambiguous reference rather than meaning. A settled name is what the people actually living there call it, and it can differ completely from the catalogue string — using both in the same story, and letting different characters favour one or the other, is a fast way to show who a character is without stating it.

Sources and Further Reading

• International Astronomical Union — Naming Astronomical Objects
• International Astronomical Union — Naming of Exoplanets
• IAU NameExoWorlds — public exoplanet naming campaign
• NASA Solar System Exploration — Uranus Moons In Depth (Shakespeare and Pope naming convention)
• NASA Solar System Exploration — Jupiter Moons In Depth (mythological naming)
• Wikipedia — Exoplanet Naming Convention