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[[quoteright:350:[[Series/{{Andromeda}} http://static.tvtropes.org/pmwiki/pub/images/rsz_magogworldship1_7654.jpg]]]]
[[caption-width-right:350:Seldom has 'starship' been so literal... or insufficient.]]

There's big spaceships, there's ''[[MileLongShip gigantic]]'' spaceships, and then there's these: a space ship (or station) that's as big as a small planet or large moon. In space, you have no external gravity to contend with, so it's possible to build some truly humongous structures like this. Alternatively, you may just want to strap some engines onto an ''actual'' planet or moon and set off, although this may require SufficientlyAdvancedTechnology.

Often used for RuleOfCool, in which case it will overlap with CoolStarship, the Planet Spaceship is a great way to intimidate your foe, or to pack your entire population off when your home world is in trouble. May evoke a "ThatsNoMoon" reaction when it first appears.

Technically, actual planets and moons ''are'' spacecraft in the sense that they are in orbit around something. Buckminster Fuller made this analogy when he referred to "Space Ship Earth." But to qualify for this trope, the super-colossal spacecraft must have some means of ''propulsion'', or at the very least orbital correction.

Subtrope of MileLongShip. May be used as a BigDumbObject, TheBattlestar, or a GenerationShip. Commonly, though not exclusively, found in SpaceOpera. Compare DysonSphere and RingWorldPlanet. See also: UnnecessarilyLargeVessel, UnnecessarilyLargeInterior and AwesomeButImpractical.

!! Examples:


[[folder:Anime & Manga]]
* The Zentradi main base in ''Anime/SuperDimensionFortressMacross'' is hundreds of kilometers across. Of course, the Zentradi themselves are giants.
* There's a ship in the Raalgon fleet, in ''Anime/IrresponsibleCaptainTylor'', that causes Tylor himself to comment that it's "more like a planet than a ship".
** And it is outclassed by an even bigger ship in the final OVA.
* In ''Anime/TengenToppaGurrenLagann'', the final battle has the two sides fighting with mechas that are on the same scale as ''galaxies!''
** You don't even need to go that far to find planetoid-sized vessels in TTGL. The Super Galaxy Gurren Lagann/Cathedral Terra was large enough to be disguised as [[spoiler:the moon.]]
* ''Anime/TransformersCybertron'': The planet Cybertron, the alternate mode of Primus (basically the transformers god), can transform into a spaceship of sorts.
* In ''Manga/{{Outlanders}}'', Earth's moon is revealed to be a millennia-old ship, the superweapon called "Dola".

[[folder:Comic Books]]
* Taa II, the Worldship belonging to the MarvelComics character {{Galactus}}, and named after his ravaged homeland Taa, is the size of ''a solar system''.
* The homeworld of the Evronians in ''PaperinikNewAdventures'': they turned it into a [[CrazyAwesome spaceship]]. And, as it wasn't enough, they also ''built a starship the size of a small planet'' for their Emperor. Both have been destroyed by [[PhysicalGoddess Xadhoom]], Evron off-screen (it's mentioned by some survivors well after the fact) and the starship of the Emperor on-screen.
** In the 2014 relaunch we discover that the Evronians in the BadFuture did it again: they transformed another planet in a spaceship, in this case [[spoiler: Earth]]. Took them two hundred years...
* Mogo, the Sentient Planet is a Green Lantern, and effectively becomes this as he can travel through hyperspace.
* Warworld, which frequently falls into the hands of {{ComicBook/Superman}}'s GalacticConqueror enemies.

[[folder:Fan Fiction]]

* The {{Daria}} ExpandedUniverse has the ''[[TheChosenMany Corps of Ringbearers]]'', who police the various realities for supernatural threats. Their greatest weapons are the seven ''Sky Vaults'', each of which is roughly ''one-third the size of Earth's moon.'' They are fearsomely armed with '''five''' [[WaveMotionGun solar cannons]], a wealth of other armaments - but are considered to be [[GodzillaThreshold weapons of last resort or of final escape]] [[GenerationShip in order to save as many species as possible]] from [[ApocalypseHow an omniversal threat to Reality itself]]. The Corps took the latter option during ''[[CrisisCrossover The Judith Saga]]'', and haven't been seen since.

[[folder:Film - Animated]]
* Titan, for which ''WesternAnimation/TitanAE'' is named, is a very large, spherical spaceship. When activated, it converts energy into mass and [[spoiler:turns into an actual planet.]]


[[folder:Film - Live Action]]
* In ''Franchise/StarWars'', the ''Death Star'' is a moon-sized superweapon which is the original source of the ThatsNoMoon trope. For specificity's sake, the first Death Star was established as 160 kilometers in diameter, and the second would've been 900 kilometers or twice as big as the first one (there are contradictory reports) if it hadn't been blown up first.
* Spaceball One in the movie ''Film/{{Spaceballs}}'', a parody of ''Franchise/StarWars'', has a similar scale.
* The alien mothership in ''Film/IndependenceDay'' was estimated to be several hundred kilometers in diameter.
* The ''Tet'' from ''[[Film/{{Oblivion 2013}} Oblivion]]''.

* In the Ted Reynolds short story, "Ker-Plop", we get a reminder of the difference between size and volume, when humans return from the Magellanic Clouds in a ship that is ten thousand kilometers across (about 1/10th the diameter of Ceres). The agent sent to investigate realizes that because the ''entire volume'' is inhabited, rather than just the surface, this one ship contains more people than his ''entire galactic federation''. The decks are arranged concentrically, like an onion, and the first kilometer ''alone'' has nearly ''400'' decks, each with nearly ''the same surface area'' as the entire ship!
* In Creator/EEDocSmith's ''Literature/SkylarkSeries'', Drs. Seaton and Crane build a 1000km diameter spaceship called the ''Skylark of Valeron''. Its size was needed to house the sensors required to travel at its full velocity. Later, their rival Dr. [=DuQuesne=] builds an even bigger ship.
* In Creator/LarryNiven's ''Literature/KnownSpace'' series, the Pierson's Puppeteers are a race of cowards, and the only Puppeteers humans have met are insane-- because no sane Puppeteer would trust his life to something so fragile as a spaceship. So when they discover a massive wave of radiation approaching their home system, they leave it behind... but take their planets with them. They put them in orbit around each other (see [[http://en.wikipedia.org/wiki/Klemperer_rosette Klemperer Rosette]] on TheOtherWiki) and accelerated them to just under lightspeed, heading out of the galaxy. Because humans have faster than light starships (which Puppeteers are too sane to use), they expect humans to greet them at their destination, the Clouds of Magellan.
* In the ''Literature/{{Gor}}'' series:
** The planet Gor itself can be considered an example, since the Priest-Kings (the PhysicalGods of the planet) moved it to its current location 5 million years ago.
** The Kurii live in "Steel Worlds" in the asteroid belt; from there they plot their plans to destroy the Priest-Kings and take over Gor & Earth for themselves. The Steel Worlds have aritifical weather & daytime/nighttime and rotate to simulate gravity, with beings living on the inside circumferance of the ships. They used to have a planet of their own but they destroyed it making war with each other.
* Creator/DavidWeber's ''Literature/EmpireFromTheAshes'' series has ''Dahak'' and all the other Imperial Planetoids. ''Dahak'' has spent the last 50,000 years pretending to be Earth's Moon... and it's the smallest of them. They come equipped with hundred kilometer thick armor and carry 80,000 ton battleships as parasite craft.
* In Creator/JohnVarley's ''Literature/GaeaTrilogy'', Gaea and her brood are [[LivingShip living space habitats]] large enough to be mistaken for additional moons of Saturn.
** Varley also uses this trope in his short story "The Funhouse Effect": a large comet in a close solar orbit is partially hollowed out, has engines mounted on it and is being used for exclusive pleasure cruises 'round the Sun.
* In ''The City and the Stars'' by Creator/ArthurCClarke, it is revealed at the end that [[spoiler: most of the humanity left the Galaxy to explore the universe... in a star cluster made into a fleet.]]
* At the end of ''Literature/HaloTheColeProtocol'', the inhabitants of The Rubble, survivors of the Covenant invasion of their system, convert a large asteroid into an evacuation ship to get everyone safely to UNSC space.
* In ''Literature/{{Remnants}}'', the humans who awaken when the ship reaches a destination initially think they've landed on a bizarre alien world. They soon discover it's a massive spaceship controlled by a sentient AI that brought them aboard as a curiosity.
* In Creator/RobertReed's ''Literature/GreatShip'' series, the Great Ship itself is an [[BigDumbObject ancient abandoned artifact]] which was claimed and settled by mankind's descendents. It is larger than Jupiter. The interior of the ship has [[StarshipLuxurious hundreds of thousands of enormous caverns which are inhabited by the passengers]]. The ship has fourteen gimbaled fusion engines on one end, each of which is large enough to fit several dozen Earth-sized planets within their nozzles, which are fed from dozens of hydrogen fuel tanks whose individual volume exceeds that of all the Earth's oceans combined by several orders of magnitude. In ''The Well of Stars'', a planet ''weapon'' is shown - the Sword of Creation - a planet-wide [[MadeOfIron hyperfiber]] ring which has microscopic black holes tethered to its rim, which is then spun up and repeatedly launched at planets to expose a path to its core for mining.
* Creator/CordwainerSmith gives us The Golden Ship - a sphere 90 million miles in length (just 2 million miles short of an AU). That's approximately 100 times larger than Earth's sun! Extremely fast, it could move in seconds. [[spoiler: However, the Golden Ship is really a decoy, being mostly hollow and consisting of foam and wires. It has no weapons of its own, and must rely on its speed to survive.]]
* The largest vessels in the ''Literature/PerryRhodan'' series fall under this trope. For instance the cosmocratic spore ships, spheres with a size of 1126 kilometers.
* ''Literature/TerreEnFuite'' (''Fleeing Earth'') is a novel by François Bordes where Earth (with the Moon in natural gravitational tow) and Venus are turned into giant spaceships in order to allow humanity to escape the Sun going nova. Initially, the plan is to wait out the explosion behing Jupiter and come back. However, scientist then determine that the Sun will not return to its former state, so they have to move the planets to another system... and then again when the first one turns out to have a LostColony of humans.
* In ''Literature/TheWitchesOfKarres'', the so-called witches use their "Sheewash drive" to move the entire planet of Karres around when they need to.
* Zonama Sekot in the ''Franchise/StarWarsExpandedUniverse'' is a case of attaching absolutely enormous hyperdrive engines to a [[GeniusLoci (sapient)]] Earthlike planet.
** The Yuuzhan Vong have massive Worldships which hold most of the races population. They were used by the Vong to travel from their galaxy to the galaxy of the protagonists. Their also used as warships, and are thrice the size of a Super Star Destroyer.
* In the PiersAnthony book ''Macroscope'', SufficientlyAdvancedTechnology allows four humans to turn the entire planet Neptune into a machine that can carry them to different locations in space instantly, [[Literature/AWrinkleInTime tesseract-style]].
* The larger models of Culture General Systems Vehicle from Creator/IainBanks' ''Literature/TheCulture'' fall here. The things can be anywhere from [[MileLongShip 25]] to 200 kilometers in size, and carry millions of passengers and can match planets for industrial production. One scene shows four kilometer oceangoing ships being packed away for storage inside a GSV.
* In the ''Literature/StarCarrier'' novels the Turusch build their larger warships by hollowing out large asteroids and adding engines. An extreme example of this is the ''Regrets of Parting'', made from a dwarf planet at least 900 kilometers in diameter and massing about 900 quadrillion tonnes.
* Creator/EdmondHamilton gives us [[http://thenostalgialeague.com/olmag/hamilton-thundering-worlds.html Thundering Worlds]], in which every planet in the solar system is outfitted with nuclear rockets and flown to another solar system to escape our dying sun. Of course, then they pass by some [[OhCrap hostile aliens and give them the same idea...]]
* The Polish sci-fi novel for teenagers ''Ci z dziesiątego tysiąca'' (''Ones from the Tenth Thousand'') by Jerzy Broszkiewicz mostly takes place on a "mechanoplanet": a large, intelligent spherical spaceship with artificial environment.
* [[spoiler: In the final book of the {{Tunnels}} series, Planet Earth itself is revealed to be one of these.]]

[[folder:Live-Action TV]]
* In ''Series/{{Andromeda}}'' the Magog come from worlds (yes, that's plural--twenty of them) locked together in some kind of structure. The whole thing is mobile, FTL capable, and even contains an artificial sun. [[spoiler: Oh, and it can survive a hit from a Nova Bomb, the largest weapon in the Commonwealth arsenal, normally capable of nuking entire solar systems.]]
* In the ''Series/StarTrekTheOriginalSeries'' ep. "For the World is Hollow and I Have Touched the Sky" a group of aliens have been sequestered inside a large interstellar asteroid for so long that they have forgotten that they are actually inside one.
* ''DoctorWho'' has had one or two in its 50-year history. First, the Daleks ''attempted'' it in "The Dalek Invasion of Earth," but failed. The second, and somewhat more successful of these, was Zanak from "The Pirate Planet," a hollowed-out planet with massive transmat engines...it could materialize around another planet and capture ''everything'' from it, leaving behind a tiny husk, which its captain could collect as a trophy.
** The TARDIS itself probably is this. Just not on the outside.

[[folder:Tabletop Games]]
* In ''TabletopGame/{{Warhammer 40000}}'':
** Eldar craftworlds are described as "planetoid-sized".
** The Necron World Engine, unsurprisingly, is a Necron ship the size of a planet (because they slapped an engine on a planet). An entire space marine chapter sacrificed itself to destroy it.
** Also, the [[http://wh40k.lexicanum.com/wiki/Phalanx Phalanx]] is the moon-sized fortress-monastery-spaceship of the Imperial Fists.
* ''World Of Synnabar'' takes place in a spaceship made from a hollowed out Mars.
* In ''TableTopGame/Pathfinder'', Apostae, the tenth planet from Golarion's sun, called "The Messenger", is one of these. It's a GenerationShip, with it's crew/cargo trapped inside, horribly mutated and deformed, having long since lost control of the ship and memory of their mission, if they ever had it to begin with.

* In ''Franchise/{{Bionicle}}'', Mata Nui was designed to observe other universes while having beings inside him functioning as NanoMachines in a sense. His HumongousMecha body is roughly forty million feet (7,575 mi or 12,192 km) tall and had a camouflage system that created an island on his face. Mata Nui was able to control specific things like gravity and light within his body.

[[folder:Video Games]]
* In ''VideoGame/{{Marathon}}'', the eponymous ship was originally Mars' moon Deimos. This is less impressive than it sounds given that Deimos is about six kilometers long... fairly big by human standards, but nowhere near the size of a planet.
* The ''Dammerung'' in ''VideoGame/{{Xenosaga}}'' is described in the accompanying Perfect Works manual as an artificial planet the size of Lebanon. It's the headquarters for {{Fiction 500}} company Vector, and contains at least one megalopolis in an area large enough to have a real weather system.
* In the videogame adaptation of ''WesternAnimation/{{Futurama}}'', Mom's plot involves transforming the Earth into a giant spaceship.
* In ''Videogame/StarRuler'', the players can make ships anywhere from the size of a coke can to ships larger than the galaxy. At around ship scale 1000, ships start to become larger than the planets that build them. Additionally, it's possible to turn entire ''planets'' into ships by researching the Planetary Thruster. Building a bunch of planetary thrusters, some shield generators, and planetary laser cannons essentially turns the planet into a [[StoneWall ridiculously durable, but relatively poorly armed ship]] with the capacity to store thousands of smaller ships, or [[MookMaker build]] [[MobileFactory more ships]] on the way to its destination by importing goods from the galactic bank.
* ''Franchise/SonicTheHedgehog'' has The Death Egg, a parody of the Death Star. The intro of ''Sonic & Knuckles'' illustrates just how big it is--the Eggman face fills the top of a volcano (Lava Reef, to be exact).
* The ''VideoGame/{{X}}-Universe'' series' backstory provides an extreme example. Billions of years ago the Ancients fought a several-million-year-long war against a [[JustForFun/AbusingTheKardashevScaleForFunAndProfit Kardashev Type V+]] race called the Outsiders who are believed to have invaded from another universe. They entered ours in the form of several ships that were each the size of a solar system. (Yeah, SufficientlyAdvancedAlien doesn't even begin to cover this.)
* The first two games in the ''VideoGame/MightAndMagic'' series has an implicit case: the worlds they take place on are indicated to be just two out of several carried by an [[{{Precursors}} Ancient]] automated vessel. Both CRON and VARN (the worlds in question) are decently-sized themselves, giving some inkling of the minimal size of the vessel. The third game does not actually take place on this ship, but the islands on planet it does take place on were once smaller such worlds on the ship that were placed on the planet by the Ancients as colonies. On a more minimal scale, the villain of ''World of Xeen'' (the combined ''IV''/''V'') planned to use XEEN as this (the problem is that while it would indeed be entirely possible to do this, it'd kill the natives, at least with the villain's implementation).
* The Voth fortress-ship in the ''VideoGame/StarTrekOnline'' PVE raid "The Breach". Starfleet's ''Odyssey''-class has been scaled as roughly a kilometer in length, and this thing probably dwarfs a hundred Oddys nose-to-stern. Oh, and it carries multiple ''Citadel''-class dreadnoughts within it like fighters, each of them roughly 10 km long.

[[folder:Web Original]]
* ''[[http://1d4chan.org/wiki/The_ship_moves The Ship Moves]]'' (Or ''Warhammer 50,000: Age of Exodus''), a variation setting based off of TabletopGame/{{Warhammer 40000}} crafted on the /tg/ board of Website/FourChan.
** It begins with the Main/{{God Emperor}} waking up and giving a set of orders before going back to bed. Said orders result in the creation of The Ship. With a keel of approximately One Astronomical Unit in length (1 AU = 149597871 kilometres), the remains of the Imperium stripped to build it, Holy Terra itself hollowed out and fitted with cogitators and command system and the Imperial Palace itself becoming the bridge and God-Captain of Humanity guiding it.

-->The Ship is the Imperium.\\
The Imperium is the Ship.\\
The Ship is the Emperor.\\
The Emperor is the Ship.\\
All is the Ship.\\
The Ship is All.\\
'''The Ship Moves'''.
[[folder:Western Animation]]
* In ''WesternAnimation/InvaderZim'', the original inhabitants of Mars drove themselves to extinction converting their planet into a giant spaceship.... "[[RuleOfCool Because it's cool]]". [[spoiler: a similar thing happened to Mercury, which leads to an awesome dogfight.]]
* ''WesternAnimation/ShadowRaiders'' feature a handful of planets with engines designed by an unknown precursor race.