"It is true what they say: Women are from Omicron Persei 7, men are from Omicron Persei 9..."
— Ndnd of the planet Omicron Persei 8
, "When Aliens Attack"
In speculative fiction, inhabited planets will often lack a proper name, instead being designated by the name of the star they orbit and a number. It is almost never the case that the star is referred to by a catalogue number. Natural satellites will also often lack proper names and be identified as "the moon of planet X" or somesuch.
In Real Life
, notable celestial objects, like the other planets of the solar system, their moons and certain stars easily visible from Earth have had proper names for about as long they have been known to exist (although admittedly some are much better known than others). A large number of lesser objects, such as asteroids and extrasolar planets are assigned catalogue numbers. When extrasolar planets were first discovered in 1995, the astronomical community used lowercase letters instead of numbers (e.g. 51 Pegasi b, 70 Virginis b). While it is reasonable that an interstellar civilisation surveying a star system would initially assign numbers to the planets along the lines of "XLL325-1" for the first planet of the star XLL325, it would be strange if they failed to come up with proper names for the star and planets (eg. "Baltimore
" instead of "XLL325") if they decide to colonise the star system. Even sillier is when a planet inhabited by an alien species is given such a label and said inhabitants begin to use that designation themselves. It's sillier still if the species has always
called their own planet by a catalogue number. After all, how many humans in reality or fiction ever refer to our little world
as Sol III?
This trope is arguably justified when the catalogue number is used by The Empire
to name planets occupied by another species. Starfish Aliens
may call their planet Krzjdlwsk (which, admittedly, would probably still be pronounceable in some terrestrial language), but stormtroopers trying to pronounce the name may be tempted to just use the catalogue number or come up with a nickname for the planet, like "Krazy Dullwhisk." May sometimes be a case of Translation Convention
The trope can also be justified as a naming convention by a bureaucratic or military authority that wishes to come up with a neutral name that does not offend political sensibilities. This sort of thing is common on Earth, as anyone who's visited (London)derry in Northern Ireland or the Persian (Arabian) Gulf can attest. If two competing groups settle a planet, and one calls it Cleveland while the other calls it Cayuga, it might just be best for a visiting starship captain to call it "Rigel VI".
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Anime and Manga
- In Magical Girl Lyrical Nanoha Earth is also "Unadministrated Planet #97" to the Time-Space Administration Bureau. The Bureau categorizes the known worlds into administrated, non-administrated, and uninhabited, and numbers them (possibly) by the time of discovery. Mid-Childa, its homeworld, is "administrated world #1", for instance.
- Outlaw Star uses this a lot, first with Sentinel III, and later with planets in the Heifong system.
- Non-spatial example: Japan is renamed Area 11 in Code Geass.
- This is chiefly a political move by Britannia, as it removes the identity of the conquered country to make it harder to establish a cause to revolt by.
- Early in the series there's a reference to part of the former Middle East (Saudi Arabia) being referred to as Area 38. Presumably these numbers designate actual places under rule by the Brittanians.
- In the Gundam series, especially but not exclusively in the Universal Century timeline, The Earth Federation names clusters of its artificial space colonies as "Sides", with the numerical designation of "Side x". For example, Amuro Ray's home cluster was designated as "Side 7".
- Each of the seven Sides has an actual name in addition to its Side number, though these are rarely used for some reason. The names are, in order, "Zarn", "Hatte", "Munzo" (or "Zeon" for most of UC), "Mua", "Loum", "Riah", and "Noa". Individual colonies tend to have both a numerical designation and an individual name (Side 1, Colony 1 is "Shangri-La").
- Dragon Ball Z has a minor example in Frieza's conquered planets - they all bear his name (indicating that he owns them), and a numeral, probably to indicate in what order they were obtained. Vegeta recovered on Planet Frieza-79 before heading to Namek.
- Legend of the Galactic Heroes: Rondolina, a planet which plays an important role in the backstory, was also known as Sirius VI.
- Voices of a Distant Star has Sirius IV.
- Bodacious Space Pirates has Tau Ceti III (or Uminoakehoshi)
- DC Universe: Talok III, IV, and VIII, Beltair IV, Trigus VIII, Toomey VI.
- The Marvel Universe has Centauri IV, Sirius III-IV, Rigel III, Capella II (whose natives call it Lotiara), Arcturus IV, A-Chiltar III, Ciegrim-7, Horus IV, Maklu IV, Stonus I-V, Tarnax IV, Wundagore II and Power Planet 4.
- Primortals: Achernar III.
- Les Mondes d'Aldébaran is set on Aldebaran IV (also known simply as Aldebaran).
- In Aeon Natum Engel Earth is classified as ǶǡѬѮӜ-[(zero-46,656) and (thirtyone-1296) and (eleven-36) and (thirtyfive)]-[(zero-60,466,176) and (one-1,679,616) and (twentynine-46,656) and (seven-1296) and (seventeen-36) and (three)]. Would be considered as a case of Exaggeration if not for beings who are using that numbering system, the Migou.
- Planton V from Calvin and Hobbes: The Series.
- Used occasionally in Star Wars: Yavin 4 is actually the fourth moon of the planet Yavin, there is also Hoth VI, Aduba-3, Telos IV, Malachor V and so on. However, the vast majority of planets where people actually live (Yavin 4 was just a base, for example) have a proper name, like Naboo, Coruscant, Tatooine and Kamino, although one (possible) exception is "(the Forest Moon of) Endor" where the Ewoks live. Justified because Ewoks are tribals, not a spacefaring race, and have no concept of astrography.
- The Chronicles of Riddick have Helion Prime and then up to Helion Five.
- Star Trek II: The Wrath of Khan's main plot begins when someone mixes up the planets Ceti Alpha VI and Ceti Alpha V (one of them blew up and the other's orbit was shifted and became a desert wasteland as a result). Whoever forgot to COUNT THE FREAKING NUMBER OF PLANETS when they arrived in the system deserves to have some sort of parasitic worm shoved in their ear...
- In real life, however, Pluto is not always the farthest (dwarf) planet, so when it happens, it's easy to confuse it with Neptune if one doesn't know their masses etc., but only counts objects.
- The planet where both Alien and Aliens takes place on is called LV-426, though in the latter its also known as Acheron.
- The third movie has Fiorina 161.
- Prometheus is set on LV-223.
- Enemy Mine had Fyrine IV.
- Forbidden Planet is set on Altair-4.
- Fantastic Four: Rise Of The Silver Surfer mentions Rigel III as the previous planet eaten by Galactus.
- Lost in Space: Alpha Prime.
- Screamers is set on Sirius 6B.
- In Good Boy!, all dogs are aliens from the planet Sirius VII (the Dog Star, geddit?)
- Proxima Centauri may be the Ur Example, with the planets Centauri I and Centauri II.
- Not uncommon in The Hitchhiker's Guide to the Galaxy, sometimes using Greek or Roman letters instead of numbers, for variety. Several planets did have actual names, however: Earth ("What a boring name..."), Magrathea, Golgafrincham,
- Not usually used in Isaac Asimov's Foundation series, except for Gamma Andromeda V.
- Clans Of The Alphane Moon has Alpha(Centauri) II and Alpha III M2
- In Lois McMaster Bujold's Vorkosigan Saga novels:
- The Cetagandan Empire does this with Greek letters. There are eight planets and they're all "Something Ceta" - Eta Ceta, Rho Ceta, Mu Ceta and so on.
- Cordelia Vorkosgian's homeworld of Beta Colony is technically a numbered homeworld, though Alpha Colony and Gamma Colony have since disappeared. As the name implies, it's very close to Earth in normal space (rather less so via the wormhole network, compared to other planets).
- The planet Kibou-daini means "Hope #2", number sign and all — it's a very formal and technical form in Japanese and isn't usually seen out of signs and manuals. This is because there are multiple worlds called "New Hope" or the equivalent, and the two is required to distinguish it from the others.
- There are also more typical examples, like Dagoola IV, or Tau Verde IV.
- A Far Sunset is set on Altair V.
- As On A Darkling Plain, by the same author, has Sirius A II, otherwise known as Makta.
- In the Dune series of novels, the homeworld of the Ixians is called Ix, a mysterious name with a meaning lost to time. One character with "ancestral memories" notes to himself with amusement that "Ix" is merely the name of a numeral from a culture that has long been forgotten by the general population of the present universe. Seemingly implicit is that the planet was originally designated with the number 9, written in Roman Numerals as IX.
- Several other plants have numbers, such as Salusa Secundus, Wallach IX and IV Anbus (pronounced as "four-anbus").
- The video game adds Sigma Draconis IV. The name is totally in character for the House Ordos who live there.
- Robert A. Heinlein's various stories have: Capella VIII, Spica IV, Planet P, Beta Corvi III, Epsilon Gemeni V, Gamma Leonis VIb, Shiva III, Thaf Beta VI, and Thoth IV.
- Arthur C. Clarke's The Songs of Distant Earth has Sirius X.
- SpaceWreck: Ghost Ships And The Derelicts Of Space has one story set on Alshain IV.
- Usually averted in Humanx Commonwealth, the only exception being Tharce IV.
- Stephen King's The Tommyknockers briefly features Altair IV, which may be a reference to Forbidden Planet.
- LV-426, the setting for Aliens is named Acheron in the novelisation.
- Although called Darkover by the natives, the Terran Empire's name for the planet is Cottman IV.
- Seeds Of Light: Sirius B III.
- In Harry Turtledove's Worldwar series, The Race's homeworld is named Home, and the other two planets under their rule are follow the [Star][number] convention - Halless 1 and Rabotev 2. They call their latest target Tosev 3, the third planet from the star Tosev. The Tosevite locals call it Earth.
- Asteroid B612, home to The Little Prince.
- The Choose Your Own Adventure book The Third Planet From Altair: It's right there in the title.
- Revolt On Alpha C: Alpha C(entauri) IV.
- Possibly justified in Stephen Baxter's Manifold: Space. The Gaijin refer to their homeworld as Zero-zero-zero-zero, indicating it's their "point of origin," but the Gaijin are Mechanical Lifeforms who don't have a human-like mode of consciousness.
- The Perry Rhodan universe has the Arkonides calling their homeworlds Arkon I, II and III. This is quite intentional, since they were moved into an equilateral triangle with the star in its center (they were originally the 2nd to 4th planet). The other planets in the system have names.
- There are also more traditional examples, like Betelgeuse III and the planets of the Vega system (IX, X, XL)
- In The History of the Galaxy series, many secret Earth Alliance automated bases throughout the galaxy are called "Omicron"+<serial number>. This is likely to hide their locations from enemy spies.
- The Alliance/Union universe has Alpha Station, Beta Station, and Omicron Point. Gehenna is also officially known as Zeta Reticuli II.
- In one of the Lensman novels, Tregonsee comments in passing that he thinks of his homeworld as Rigel IV, and only bothers with a more accurate designation if he needs to give astrogation coordinates. This implies that the Rigellians don't have an independent name for their homeworld (but could simply be Lens-related Translation Convention).
- Some other planets from the series are also named this way, such as Aldebaran I and II, Lyrane II, Thrallis II and IX, Palain VII, and Velantia III.
- In Jack Vance's Allastor stories, the planets of the Allastor Cluster all have numerical designations as well as names, so Allastor 933 is also Marune, planet 2262 is also Trullion, 1716 is Wyst, etc.
- One of Vance's other stories, The Book Of Dreams, has Arcturus IV.
- Emphyrio has Capella V, although it's also known as Maastricht.
- The Demon Princes mentions Caph IV, Mizar VI, and Xi Puppis X.
- The Last Castle has Etamin IX.
- Space Opera has Phi Orionis II, otherwise known as Zade.
- In Poul Anderson's Tau Zero, the Leonora Christine's original destination was Beta Virginis III.
- Philip K. Dick's Shell Game is set on Betelgeuse II.
- Vernor Vinge's Conquest By Default: Epsilon Eridani II (otherwise known as Miki).
- In Sergey Lukyanenko's Rough Draft and Final Draft, all parallel worlds have a numerical designation, the origin of which is not known. Our world is Earth 2. Many of the mentioned worlds have proper names, although the numerical designation is used most often. For example, our world is sometimes called Demos, due to the prevalence of democracy. It was initially assumed that there are only about two dozen parallel worlds. However, the number is later revealed to be at least double that (possibly, infinite) with Earth 46.
- Gordon R. Dickinson's Childe Cycle has Fomalhaut III, better known as Dorsai.
- The Ship Who Sang: Beta Corvi IV, which was referenced in Star Control.
- By the same author, The Rowan has a character from Deneb VIII.
- Kevin J. Anderson's The Saga of Seven Suns: Paris 3, Qrohna 3, Constantine III, Jonah 12.
- Almost entirely averted in Ursula K. Le Guin's Hainish novels. The exception is Eleven-Soro, which features in only one short story, "Solitude".
- The setting of Rocannon's World was known as Fomalhaut II before being renamed Rokanan.
- The Star Wars Expanded Universe generally does this quite realistically—the only planets with numbers are those home to small or recently founded colonies, such as Comkin Five.
- Serpent's Reach: The Majat homeworld is Alpha Hydri III (although the Majat call it Cerdin).
- Stanislaw Lem's The Invincible: Regis III.
- Tauf Aleph has Tau Ceti IV.
- In one of the Soul Drinkers novels, an Adeptus Mechanicus world is referred to solely by a "serial number"-type name. Of course, given the nature of that particular branch of the Imperial hierarchy, that's about par for the course.
- The Hyperion Cantos have variations with Deneb Drei and Deneb Vier, Sol Draconi Septem, and Vitus-Gray-Balianus B.
- David Weber's The Apocalypse Troll: Sigma Draconis IV.
- City At World's End: Vega IV.
- The War Against The Rull: Eristan II and Mira XXIII.
- Cordwainer Smith's The Dead Lady Of Clown Town (part of the Instrumentality series): Fomalhaut III.
- Robert J. Sawyer's Calculating God has Groombridge 1618 III.
- The Winds Of Altair is set on Altair VI.
- All planets mentioned in Way Station are named this way: Thuban VI, Polaris VII, Mizar X, Vega XXI, Enif V, Alphard XX, etc. So not only are all the space-faring aliens in this region of the galaxy conveniently from star systems humans have names for, but they also seem to have no other names for their homeworlds, and no names for themselves besides "Thubans" and "Vegans". (Although to be fair, Earth is also referred to as Sol III.)
- Total Eclipse features Sigma Draconis III.
- Unearthly Neighbours: Sirius A IX.
- Planet #666 from Jason X Planet Of The Beast.
Live Action TV
- Commander Perkins: The Vega Series has Vega VIII.
- The Space Gypsy Adventures has the Galvert system with several inhabited planets differentiated simply by number. Detective Constable Bones is from Galvert VI but the characters visit several other worlds in the system. Other planets such as Zenophon aren't numbered.
- Traveller uses arbitrary numbers for the least important systems. For example, here's a map centered on 876-574. (More important systems will more usually be known by the name of their most important habitation, be it artifact, planet, moon, or asteroid belt.)
- Warhammer 40,000 uses names like Lorne V and Kaurava IV on top of more standard titles. But the also tend to name a star system after its most important planet, a subsector after its most important system...
- Tékumel was previously known as Nu Ophiuchi d or Sinistra d.
- Tallon IV, although it's sort of confusing in Metroid Prime. There's a room that gives you a holographic display of the solar system. Tallon IV is actually the fifth planet in that system and the system itself is called the Ooromine System. There is an Ooromine II, but the other planets have distinctive names. This includes Zebes (the planet of the original Metroid and Super Metroid), Billium and Twin Tabula.
- The Metroid home planet is SR388. Justified as the name is a catalog name given by the Federation. The planet was never colonised by them (due to certain nasty energy-sucking jellyfish-things) and so there's no reason for a proper name. Samus' own home colony is K2-L.
- The second Alien vs. Predator game takes place upon LV-1201.
- EVE Online:
- Every planet and moon is numbered. Only planets in the homeworld systems of Amarr, New Caldari, Luminaire, and Pator, get proper names.
- Furthermore, the systems not controlled by the NPC empires all have numeric designations like B-VIP9. There have been proposals to name some of these systems after characters whose players died in real life.
- Endless Space uses it. Even your empire's homeworld is literally a numbered homeworld.
- Starbound plans on this with the star name, then the number with Roman numerals and then moons around said planets are given alphabetical designations in order of closest to farthest. One example could be Alpha Nu Aql Majoris III b. The player's homeworld, however, can be named.
- This trope exists in the Halo universe with the planets Chi Ceti 4, Eridanus II, Charybdis IX, Epsilon Eridani IV, and Sigma Octanus IV. There are also a few numbered planets that aren't named after the star they orbit; Beta Gabriel, Draco III, Paris IV, and Jericho VII. Jericho VII is especially odd, the UNSC colony Arcadia is within the Jericho system while the Jericho VII itself is in the Lambda Serpentis system.
- In the 4X game Galactic Civilizations II the homeworlds of the various species and the other planets in the same system have proper names. Other systems with no native intelligent species however have planets with Star Name + Number. The player is free to rename them though when colonized.
- Minor races have their planets named after them. Some, like the Dark Yor, even have their own solar system (following the standard naming convention for the various planets).
- The campaign maps usually have a few planets with unique names.
- The Star Ocean series uses both this and proper names for planets. For example Earth is also known as Sol III while Expel is also known as Arcura IV.
- The second and third Master of Orion games all have numbered planets. You can name the star though, so you can settle on Trope IV.
- In Xenosaga all of the capitals of Galaxy Federation have been named _th Jerusalem, with Earth being named Lost Jerusalem, and the capital during the game's events Fifth Jerusalem.
- There's also the planet of Second Miltia, suggesting that other planets are numbered in this way.
- By default, Outpost names the planets in this way while using the names of real stars, resulting in planet names like "Sigma Draconis I" or "Delta Pavonis II." You can, however, rename the planet to your liking, and Outpost 2 simply calls the planet "New Terra."
- FreeSpace has Altair V, Cygnus Prime, Deneb II, and Deneb III.
- System Shock 2 is set around Tau Ceti V.
- Averted in Mass Effect. Most planets and solar systems that you visit in the game have already been explored by someone, and as such already have names associated with them. Even lifeless rocks in distant nebulae have names. Some come from human mythology and history, but most have been named by the various alien races that have already been established in the galaxy for millennia. The only exceptions are 2175 Aeia and 2175 AR2, never formally explored and thus never given a name beyond the scientific designation.
- The very first planet ever visited in the series has the designation Eden Prime, even though no other Eden planets are ever encountered. The name is most likely symbolic. In the Bible, Eden was the first terrestrial human settlement and was a paradise until the humans got kicked out. In the game, Eden Prime was one of the first extra-terrestrial human settlements and was a paradise... until the geth invaded. (This plays on the mathematical notion of "prime", e.g. f'(x) is the first derivative of f(x)).
- Marathon is set around Tau Ceti IV.
- Dead Space has Aegis VII.
- In Star Trek: Birth Of The Federation, nearly all planets follow the trope. Earth and the Solar System planets are the exception. Interestingly, the first planet in a system is always called <star name> + "Prime". The rest attach Roman numerals. Cardassia Prime is the exception, as it is normally the second planet in the system, and the first planet is named Cardassia II.
- Star Trek: Bridge Commander starts with the destruction of Vesuvi III.
- In Spore, catalogue numbers are reserved for anomalies like black holes; every star or binary system has a name. Planets, however, including homeworlds, are designated using the name of the star or binary system followed by a number, except for the player homeworlds, which are named when you first start a game on that world.
- Freelancer gives the sparsely populated Border Worlds names like "Sigma-14" and "Tau-23," while those under house authority are named after places on Earth, such as "New London" or "Frankfurt."
- It doesn't matter if it's your homeworld. In Space Empires it'll still be called "Wolf 359 VIII".
- In Star Control II, planets are referred to as the name of the star plus a number (such as Procyon II, Alpha Tauri I, Gamma Kruger III, Eta Vulpecolae VI, Arcturus V, Beta Orionis II...). Aliens do have names for their homeworlds (e.g. Spathiwa, Kyabetsu, Syra, Fahz, Vlik, Falayalaralfali), but they will often use the standard name in conversation, presumably because it makes them easier to find.
- In Ascendancy, the player can name their colonies whatever they want, but the defaults are (Starname)(Roman numeral) (such as Hope II, Nougat IV, etc.)
- Several planets in Supreme Commander are named this way.
- Rigel's Revenge: Rigel V.
- AltairVI: It's right there in the title.
- Space Quest, being a parody game series (the latter ones specifically parody Star Trek) play this trope to the fullest. The gameplay of the sixth game starts on planet Polysorbate LX. Of course, one has to wonder what sort of life is possible on the 60-th planet in a star system. Actually, not much of a life. The place is a dump. And yet Captain Kielbasa has chosen it for shore leave of the crew of the SCS DeepShip 86. There are also planets Commodore LXIV, Delta Burksilon V, Klorox II, etc. Other planets seem to have proper names, though (e.g. Xenon, Kerona, Pestulon, Estros, Kiz Urazgubi, Gingivitis).
- Used regularly in the Wing Commander series. Locanda II, Loki IVnote , and Mylon II come up as plot points.
- In the Zap!! webcomic, "Stickles" (an alien race) come from Stickbat 7. The number isn't because it is the seventh planet from the star, but because they've accidentally destroyed six other homeworlds in crazy experiments. As one stickle said, "[the other planets] were too flammable."
- In the Punyverse from Sluggy Freelance this seems to be standard practice, with planets named things like Grittania-3 or Chau-5.
- Parodied in Starslip when Vanderbeam visits the planet Oculus IV, which inhabited by a race of blind aliens. Once Vanderbeam comments on the "irony", his host replies that there is none since only humans call the planet Oculus IV (they call it "J'tlz'kr") and that he's tired of every single human visitor bringing up the same observation.
- In The Pentagon War, the main planet of the Sirius system is named "America" by its inhabitants. Outsiders still refer to it as Sirius A IV, though.
- Hanna-Barbera's Galaxy Trio did this a lot.
- Kang and Kodos from The Simpsons Halloween Episodes come from the faraway planet of Rigel VII (also called Rigel IV in some earlier episodes).
- Some Transformers continuities have: Delta Pavonis IV, Rigel III, Rigel 6, Centaris Seven, Ceti Alpha Seven, Deneb IV, Hydrus Four, Floron 3, Daffodil II, Kaiba-5, Regalis V, Regulon Four, Talos Four, Taros Four, Planet Q, LV-117, Gorlam Prime, and Planet X.
- Justice League mentions Rigel IX.
- The Planet X is homaged in the animated sci-fi spoof Duck Dodgers in the 24˝th Century and the Captain Proton holoprogram (based on Flash Gordon-type sci-fi) in Star Trek: Voyager.
- As quoted above, in Futurama the Omicronians call their home planet "Omicron Persei VIII." This is a "Numbered" Star as well as a numbered homeworld. Omicron Persei just means the 15th brightest star in the constellation Perseus as seen from Earth, and it's a real star.
- And when finding out what life would be like if it were a video game, it turns out the Space Invaders were from the planet Nintendu LXIV.
- In fact almost every planet in Futurama is named this way. Thuban IX, Amphibios IX, Decapod X, Chapek IX, Dogdoo VII, Tweenis XII. there are few exceptions.
- Further lampooned and played completely straight during the second second Brain Spawn episode.
Infosphere Brain: "Clarification request. Are you the Philip J. Fry from Earth, or the Philip J. Fry from Hovering Squid World 97A?"
Brainspawn: "Earth, you fat idiot."
- In Captain Star, planets are named after the captain who discovered them, with the eponymous Captain Star holding the record.
- It has been pointed out that if a real person/alien came forward and claimed to be from a planet around a star with a recognizable name like "Arcturus" or "Vega" the claim could easily be considered to be suspicious right off the bat. It's not just that they're using our name while speaking our language (after all, when was the last time somebody told you, in English, that they're from 'Deutschland', 'Rosseeya' or 'Nippon?'), it's that there are literally billions and billions of stars, and the chances of an alien just happening to be from one of the only one hundred or so recognizable stars we have names for is a pretty astronomically small chance. Bright stars are not only outnumbered by smaller, dimmer stars by a long shot (our own sun isn't particularly bright itself, being in the upper-middle range), and just because a star is bright to us in the sky doesn't mean it's close to us, either.
- Highly luminous stars burn out relatively quickly (a few tens or hundreds of millions of years rather than the ten-billion-year life of a star like Earth's sun), making them poor candidates for inhabited planets.
- Someone using one of those neat-sounding star names is probably invoking Rule of Cool.
- A variation of this: the first Earth-like exoplanet to be discovered within its star Goldilocks Zone is named Gliese 581 g, also known as Zarmina's World.
- This is actually standard naming procedure for exoplanets in the IAU. Basically, each exoplanet discovered has been named (star name) + (lower case letter). The key difference from typical science fiction convention is that they use letters instead of numbers and that the letter corresponds to order of discovery, rather than distance from the star. For example, Gliese 581 g is not the sixth planet from its star (which we can't know for certain at this point anyway) but rather the sixth planet discovered in the system. It's actually the closest (we know of) to its star.note
- Earth would be called "Sol-3" if we didn't live on it. Officially, we could also call it Sol b since it's the first planet we discovered.