Earth is a Weirdness Magnet for cosmically significant events.
Ancient interstellar evil sealed away? It's sealed on Earth.
Futuristic, star-spanning alliance with hundreds of member races? The capital is Earth.
Some alien or another, whether it's one ship or its entire race, crash-lands, with no possible means of control for where they end up? Earth. (More specifically, the United States. (More specifically, Central Park.))
Aliens invading some random planet for no adequately explained reason? Earth.
If, against all odds, it's just next on the list for an alien menace that has conquered hundreds of worlds before it, Earth will more often than not be that elusive last planet they needed to make their conquest of the (region, galaxy, universe) complete. And almost every time, it's Earth where a resistance to the aliens' evil ways will finally succeed, no matter how improbable.
Obviously, in a particularly extreme form of Creator Provincialism, it's easier for Earthling writers to come up with sympathetic characters and situations when they're on the same planet as the viewers. But when a series has hundreds of worlds to choose from, it's amazing how often they go back to the same one.
It could be that the reason we don't hear about the invasions of other planets is that we weren't there, and we don't know about the baddies till they visit us. If that's the case, though, the universe must be teeming with ancient evils, reviving marauder races and professional invaders to the point where it's amazing any peaceful race has survived for more than five minutes.
On the other hand, maybe it's because Humans Are Special.
Of course, maybe Science Fiction shows really do show aliens invading the planet Zog just as often as they do Earth. It's just that those shows are only aired on the planet Zog, where Earth is just one of the countless Insignificant Little Blue Planets.
Both Tokyo Is the Center of the Universe and Big Applesauce taken to the MAX of the EXTREME. For subversions and aversions, see Insignificant Little Blue Planet and Earth That Was.
In "Broly: The Legendary Super Saiyan", Broly's father wants to turn Earth into the new Saiyan Homeworld. He doesn't use the planet that he previously took over because he says that Earth is the most beautiful planet in the cosmos, and doesn't take the invasion straight to Earth because he doesn't want it to become a desolate and battle scarred wasteland, which happened to said previously-conquered planet.
Especially egregious in Buu's case. Evil all-powerful djinn thingie goes on an interstellar rampage and kills three of the four most powerful guys in existence. The fourth barely manages to seal him up and hides him away on... Earth. Which seemingly was one of the few planets lucky enough not to be affected by his rampage and has nothing to do with any of this.
Averted, however, by Freeza, who pays no special attention to Earth until being defeated on an entirely different planet by someone dumb enough to happen to mention in passing where he was from.
A solitary mad scientist is able to create a bunch of androids whose powers dwarf that of Frieza and even the Super Saiyans of legend, which basically puts them among the most powerful beings in the universe. What planet did this mad scientist come from? Earth.
UFO Robo Grendizer -one of the Mazinger Z sequels- kind of subverted this. The Vegans had conquered many other planets before striking Earth. It is true Duke Fleed landed on Earth -from all places!- when he ran away from the Vegan troops, and the Vegans show a special interest for Earth, but that is because there are not so many habitable worlds (which is utterly true!). Earth, Fleed and Vega had a similar atmosphere and environment, so Earth was the kind of planet they were searching for.
In The DCU, Earth is not only the target of most of the weirdness and disasters, it's also literally the center of The Multiverse. So much so that the parallel universes in the multiverse are consistently referred to as "Earths", i.e. Earth-1, Earth-2, Earth-S, etc., even by characters who aren't from Earth, and the battle to decide the fate of the multiverse is referred to as the Crisis on Infinite Earths and decided almost entirely by beings from their universe's version of Earth.
Expanding on that "center of the multiverse" comment: it's what holds the multiverse together. Destroy New Earth (home of the main DC continuity) and it starts a chain reaction that will inevitably destroy all of existence. Imperiex tried to take advantage of this in Our Worlds At War in order to induce a new Big Bang. Needless to say, he failed.
Just to drive home the point even more, Earth is the only planet the Monitor even tries to save across the whole multiverse.
In fact, Earth 51 being destroyed was what kicked off Final Crisis.
Averted somewhat in the Green Lantern titles, where most of the non-Earthling Lanterns consider Earth to be a primitive backwater planet. The planet Oa also happens to be the physical center of the universe.
In Blackest Night, it is revealed that Earth houses the Entity, the "living light" that kickstarted life in EVERY universe, and that the Guardians claiming to be the universe's oldest living beings and that Earth is backwater was to cover this fact. This also helped explain an earlier bit of "Earth is awesome" canon: it's established that Earth is the most biodiverse planet in existence. Most DCU planets have a hundred or so different species, while Earth has millions. This makes sense once we find out that Earth is home to the creator of all life, which causes life on this planet to behave differently.
In Marvel Zombies the zombie Galacti (don't ask) manage to destroy every planet in the universe without significant incident between one issue and the next. When they get back to Earth, they face resistance and the plot changes direction significantly. Justified in that it was said that the inhabitants had forty years to plan a defense if the zombies ever came back. Another thing to remember is that by this time some of the zombies were losing their hunger as Spider-Man and Luke Cage are the first to help the humans.
Justified in the Marvel Universe; the reason so many aliens come to Earth is because a space warp in our solar system is a major Hyperspace nexus. And yes, the Marvel Universe IS filled with alien conquerors and space empires.
In Guardians of the Galaxy, Peter Quill's father, Emperor J'Son of Spartax, argues for the destruction of Earth for this very reason. He points out that in a short span of a single generation, humans have managed to defeat Thanos, the Phoenix Force and even Galactus, all on multiple occasions, each of whom had been responsible for the destruction of countless other worlds. He then suggests that should humans ever leave Earth and begin visiting other worlds, it would lead to untold cosmic disasters.
He later tears strips off Gladiator during The Trial of Jean Grey, because of his boneheaded decision to kidnap Teen Jean, pointing out - perfectly accurately - that first, she is quite obviously a frightened teenage girl, not the Dark Phoenix, second, if she really was the Dark Phoenix, the knowledge that the Shiar killed her entire family would set her off and mean that she would kill everyone present, including Gladiator, and third, her friends will come after and they will tear through armies to get her back, because that's what humans (particularly mutants) have historically done. He is right on every count, with the O5, Kitty, X-23 and the Guardians of the Galaxy promptly taking on the entire Imperial Guard to get her back.
The Builders also wonder why so many great powers and entities have come to call Earth home and, following their invasion and the events of Comicbook/Infinity, Earth is now something of a player on the intergalactic stage - or, at least, the Avengers are, being described by one young girls as 'heroes, gods', with an official Avengers presence being established in space.
Also to be taken into account is the truly obscene number of powerful gods and pantheons that call Earth home. Hercules, for instance, just one god (though an extremely powerful one who's actually physically stronger than Thor), cuts loose and matches the Skrull Skyfather in single combat, when said Skyfather has, with his wife, enslaved countless thousands of pantheons and gods. And he's not even half as prominent as Thor.
Silver Surfer: Why is it this world is always the one upon which the fate of everything hinges? Why do the miracles and nightmares always seem to come from here?
In the Pony POV Series, out of all the places mentioned in passing, the Earth ends up being the flashpoint for the Alicorn-Draconequus War.
Films — Live-Action
Transformers: Earth is always where the MacGuffin are hidden. 12,000 years ago the Allspark crashed landed in what would eventually become the bottom of the Colorado River. 19,000 years ago six of the Seven Primes hid the Matrix of Leadership in tomb made of their very own bodies in what would be Petra. If the Decepticons got either these artifacts the galaxy would be doomed, first on the list being the Humans and Autobots. The third film also reveals that the Apollo 11 moon landing was a mission for the US to explore the remains of the Ark, an Autobot ship that carried Sentinel Prime, as well as the Pillars needed to create a Space Bridge large enough to bring Cybertron near Earth's orbit.
Lampshaded and defied by Lockdown in Transformers: Age of Extinction, where he complains that every planet he goes to the inhabitants think their planet is the center of the universe.
In The Fifth Element, the Sealed Evil in a Can pops out every 5000 years to attack Earth. Justified in that an Ancient alien race hid a weapon there capable of destroying said evil, which would also have allowed the evil to wipe out all life in creation. That of course begs the question of why Earth was chosen in the first place.
This handily explains just why The Men in Black enforce the masquerade on humanity specifically: can't risk the neutral zone stop being neutral.
"There's always an Arquillian Battle Cruiser, or a Corillian Death Ray, or an intergalactic plague that is about to wipe out all life on this miserable little planet, and the only way these people can get on with their happy lives is that they DO NOT KNOW ABOUT IT!"
There isn't any Earth in Star Wars, but there is the Human homeworld and galactic capital Coruscant, pretty much the Earth-analog. It is officially the center of the Universe, with its galactic coordinates 0.0.0. Probably inspired by the Real Life NASA coordinate system that uses Earth as the center point, though more justified in Coruscant's case considering the planet is actually quite close to the galactic core. A year on Coruscant is 368 days, each day is divided into 24 hours, and these time measurements are used as the standard throughout the galaxy. Averted in that Coruscant is not depicted, or even named, in the original trilogy. All of the action takes place on other planets or in space. It is not until the prequels that Coruscant becomes a significant part of the storyline, and even then much of the action happens elsewhere. Also somewhat averted in that early on in the Republic's history, there was competition between Coruscant and Alsakan (another prominent planet at the time) as to which would be the dominant world in the Galactic Republic, with Coruscant eventually prevailing.
A disproportionate amount of Star Wars' plot, including Expanded Universe stories, also happens to take place on Tatooine despite Luke's remark that "If there is a bright center to the universe you are the planet that is farthest from".
The War of the Worlds: The original novel had a tidy explanation for the invaders' choosing Earth - Mars was dying and Earth was the only planet the Martians could reach - but the TV and film adaptations leave that part out. Possibly because we now know for all intents and purposes, Mars is dead.
Out of the ten Territories in The Pendragon Adventure, three of them are Earth. Though recent vague statements by Saint Dane suggest that more than the three Earths (and Ibara and Veelox) might be connected. To elaborate, the three Earths are just Earth in different periods of time. Since Ibara and Veelox are the same territory in the same way the three Earths are the same territory in different periods of time, it can be assumed that Earth and Ibara/Veelox count as single territories. Saint Dane just targeted the territories in different periods of time.
In the Robert A. Heinlein novel Glory Road, Earth is not the center of the universe. In fact, it is considered a slum. Earth does, however, happen to have many "gates" which makes it a transportation hub for a lot of planets.
In the Cthulhu Mythos the primary reason that so many sealed evils are concentrated on Earth or otherwise here is precisely because they are not concentrated on Earth. There's just so damned many of them that Earth ends up having its fair share of octopoid elder gods as a matter of normal statistical distribution.
In The Dunwich Horror, young Whateley's diary states that the alien intelligences are interested in Earth as an element in their long-range plans. Organic life, on the other hand, is considered an obstruction, and their real plans can get started once they erase all life on Earth and take it out of three-dimensional space.
The Hitchhiker's Guide to the Galaxy seems to completely avert this at first - Earth is a backwater world almost nobody even notices. When it gets destroyed, even Ford Prefect, who lived on it for fifteen years can't bring himself to give a damn. Then it turns out to have been the galaxy's most powerful super-computer. The trope gets played more or less straight from there on.
In Animorphs, the main front of the Yeerk invasion is on Earth, though in several books we see evidence of invasions of other planets in progress, such as the aquatic planet of Leera and the Garatron people. Played straight in The Ellimist Chronicles, where After Crayak tricks Ellimist into jumping out of Z-space into the event horizon of a Black Hole, resulting in the Ellimist becoming basically a god. The first time he fights Crayak in this form, it takes place in our Solar System, and Crayak is targeting Earth. Additionally, the Time Matrix, the most powerful weapon in the Galaxy created by the Ellimist himself, was sealed away on Earth. When it was uncovered by the Skrit Na in The Andalite Chronicles, it was resealed by Elfangor later on at the construction site where he met the Animorphs.
Although, to be fair, it was the middle of a large forest when he left it there. Damn you, California logging companies!
The main reason the Yeerks are focused on Earth is that it's a perfect world for their needs (lots of hosts who are highly adaptable).
The Honor Harrington Series plays with this. Earth is the home world, the richest planet in all of space, with the capital of Solarian League in Old Chicago. However the economics are stratified; the poor, who don't officially exist, live in ghettos as bad as anywhere. The technology hasn't really progressed in centuries, and really the eldest colonies like Beowulf have been the hubs of innovation and economy since the 'final war' well over a millennium ago. Their political position is now also in threat due to hundreds of years of believing they were impossible to ever be threatened.
Subverted in Diane Duane's High Wizardry: When Dairine Callahan magically transports herself to the galactic equivalent of Grand Central Station, she asks a passing "alien" what planet she's on. "Earth," it replies. "Oh. Well, what do other people call it?" "Oh, a whole lot of silly things. There's a directory over there." And then lampshaded and played straight simultaneously in Wizards at War when Kit tells Carmela that the reason Earth has so many UFO sightings is because humans are convinced they're the center of the universe, but it's not like alien species have so much time to waste kidnapping humans, and Carmela replies that the alien abductions are actually just because Earth is the only planet to have chocolate. There's a logical reason, but the aliens just happen to love chocolate so much they go thousands of lightyears for it?
Almost averted in Roger Zelazny's The Chronicles of Amber series. The first book, Nine Princes in Amber, reveals that Earth is but one of many Shadows of the one true world of Amber, significant mainly because Prince Corwin of Amber was exiled there. By the end of the series, however, it seems like half the royal house of Amber keeps a second home on Earth. Those were really only the ones who were specifically sent there to keep an eye on Corwin, though — the rest carved out their own private kingdoms. It is also explained away that anyone who is even tangentially involved in Amber casts Shadows as well, meaning that Corwin's long presence would have disrupted nearby Shadows and perhaps increased that "version" of Earth's importance over other Earths.
In Dune, Earth used to be the capital of the Old Empire for many millennia before the Time of Titans. Even after Omnius's coup, Earth is considered to be the core Synchronized World. The League of Nobles, however, is based on the outskirts of the former Empire, and their capital is Salusa Secundus. After the rebels nuke Earth, Corrin becomes the center of the Synchronized Worlds. Then the machines are defeated, and the Imperium is formed, making Salusa Secundus the center of the universe. House Tantor nukes Salusa Secundus, and the Corrinos make Kaitain the new center, followed by Arrakis when Paul takes over.
In The Science of Discworld and sequels, the wizards have an entire non-magical universe to study. Once a planet with actual oceans and stuff emerges, they pretty much lose interest in the rest of it. Especially when it acquires people. (There may be other lifeforms on other planets. The wizards have never asked.)
The original trilogy averts this trope. Not only Earth's location is no longer known to mankind, few even bother thinking about the concept of the origin planet of mankind.
The sequels play this straight: the protagonists believe that Earth houses the Second Foundation (and have a reason to believe so) and start a quest to find the forgotten home planet of mankind. While their original hypothesis turns out incorrect, Earth (or rather, its Moon) is revealed to actually be of great importance, being the home of The Chess MasterR. Daneel Olivaw.
While the sequels revolve around the search for Earth, this trope is still averted since the only reason said Chess Master is there is precisely because it's a good place to hide because no-one knows about it.
Miles: Old, romantic, historic Earth, the big blue marble itself. Miles had always expected to travel here someday, although not,
surely, under these conditions. Earth was still the largest, richest, most varied and populous planet in scattered humanity’s entire worm-hole nexus of explored space. Its dearth of good exit points in solar local space and governmental disunity left it militarily and strategically minor from the greater galactic point of view. But Earth still reigned, if it did not rule, culturally supreme. More war scarred than Barrayar, as technically advanced as Beta Colony, the end-point of all pilgrimages both religious and secular—in light of which,major embassies from every world that could afford one were collected here.
Largely averted in the Spinward Fringe series. Earth appears to be by far the most technologically advanced and militarily powerful world, with none of the constantly warring governments and corporations even thinking about daring to attack it. However, it's almost completely isolated itself from the rest of the galaxy and none of the events of the series take place anywhere near it.
Star Trek: Why on Earth would the capital of the Federation be... er, Earth? Star Trek: Enterprise, depending on your point of view, either justifies this or waves it away by saying that other species were out there first, but humans were the diplomats of the galaxy and formed the heart of the Federation — that without humans, it would have taken much longer or might never have happened at all. It is also noteworthy that, while the Federation is based on Earth, several presidents have been non-human.
The theory that humans are the diplomats of the galaxy can be seen as Fridge Brilliance, considering how every other race is portrayed as a Planet of Hats, meaning humans would be the only ones with practice overcoming cultural differences.
While all the 'protagonist' ships are have a primarily human crew, other Starfleet ships have been shown and mentioned that are crewed exclusively by aliens, such as several mentions of Vulcan-crewed ones. In one series of novels, the USS Titan, commanded by Riker, is said to have approximately 15% human crew.
Justified in at least one case with mention made of a Starfleet ship crewed entirely by Horta. Not many other life forms could really expect to survive in the conditions on board.
Federation star charts are apparently based on this trope as well. Earth is located in Sector 001. Of course, this is a Federation identification, with Starfleet headquarters and most primary Federation facilities on Earth.
We are never told exactly how big a "sector" is, but it is at least tens of light years based on several episodesnote It contains Wolf 359 and 40 Eridani A, which are just under 20 light years apart. 001 could well contain many other species' homeworlds as well.
With Canonicity of the Prime universe up in the air for now, many sources have come around to explain such apparent inconsistencies. Star Trek Online has Sector 001 referred to as the "Vulcan Sector", and it contains not only Vulcan and Earth, but Andoria as well. Still played straight in that the dividing line between Alpha and Beta quadrants runs EXACTLY through Earth's solar system. One mission also involves escorting a Vulcan, not Federation, medical transport, which shares design similarities to the Vulcan ships seen in the Enterprise era. This would suggest that private or noncombat starships have been independently built by individual member worlds of the Federation from the beginning, which helps to explain a lot.
There is at least a brief subversion to this with the Dominion War where Deep Space Nine and the wormhole take over the "center of the universe" position. While the Dominion would love to take Earth, the wormhole and the region around it is far more important real estate. Even Sisko would rather see Deep Space Nine and the wormhole taken back before Earth.
The Dominion, and to a greater extent the Borg, tend to describe conquering Earth to be the same thing as conquering the Federation. While, as stated above, Federation/Starfleet headquarters is on Earth, they seem to consider all the other territory in the Federation, and any opposition they might put forth, to be negligible.
This bit of logic is especially weak, since humans are shown as having far more colony worlds than any other Federation race (possibly more than all of them combined). Even if Earth were obliterated, there would still be vast numbers of humans spread out across Federation space and beyond, and Starfleet with its starships and starbases would still exist. Indeed, it is stated repeatedly over the series that interstellar colonization is part of a grand survival strategy for the human race. Thus the trope is played very straight in that Earth itself is somehow special, not just humanity.
Doctor Who practically defines the trope. Every time there's a rift, a cosmic vortex, a long-dead race returning to conquer, an evil galactic bureaucracy whose schemes require a planet-sized sacrifice, anything, it happens to Earth. The 2005 revival is a particular offender: At last count, seven different alien menaces have suffered some kind of catastrophe and, needing a planet on which to convalesce or just crash-land, chose Earth for no adequately explained reason — or they just "fell through time and space" and landed there by coincidence. (Including the Daleks. Three times.) At least in series 5 this is likely due to the fact that falling through time and space actually meant falling through the cracks in time and space caused by the explosion of the TARDIS on Earth in the penultimate episode. During the first series, no episode was set outside the Solar System. In the Big Finish Doctor Who audio Doctor Who And The Pirates, the Doctor rattles off (to the tune of "I am the very model of a modern Major General") a list of planets he's saved, and Earth is every third entry.
It should be noted that the Doctor himself is a gargantuan Weirdness Magnet, and that his fondness of Earth may be what draws a lot of stuff here. And several aliens display a variant on the Insignificant Little Blue Planet attitude, in that Earth is invaded/chosen to be blown up/whatever because no one else would miss it.
This tendency got a brief Lampshade Hanging in the fourth series finale. As the Doctor is interrupted while saving worlds left and right from interdimensional doom...
And another lampshade is hung in "The Empty Child"- The Doctor laughs about how you can barely go a week without bumping into Earth. Rose notes that it's every time they run out of milk.
In "Planet of the Ood", they're in the year 4126, and Earth is at the centre of a massive multi-galactic empire.
In the new series, the Doctor says he finds humans fascinating because their adaptability lets them survive right up to the end of time. Other races either see humans as major adversaries, or find present day Earth to be a convenient backwater planet that is populated by a less advanced and easy to manipulate species.
This actually makes a roundabout sort of sense. The Doctor's race, the Time Lords, are Sufficiently Advanced Aliens that had serious socialization problems. Bizarre events did not happen on Gallifrey because the Time Lords were powerful enough to prevent them and the planet had defenses that were virtually impenetrable to anyone trying to get in without Time Lord assistance. Until the Time War, they were pretty much unassailable. So even though they were quietly running the universe from their planet, only a select few knew of it as anything more than a legend. Hence someplace else had to be the center of the action...
Lampshaded in "Spearhead from Space" when Liz Shaw asks why earth is more likely to be attacked now. The Brigadier tells her they've been sending out probes that draw attention to them.
Lampshaded again in "Horror of Fang Rock" when a Rutan claims Earth is in a good strategic position. This would explain many of the other invasions.
Earth literally seems to be a central position in "Seasons of Fear", where Earth's central position would enable the Nimon to invade millions of worlds.
In "The Condemned" it's mentioned that because Earth is a high-risk planet the Shinus Government gives out high insurance for working there.
Torchwood: Ditto. Even more precisely, Cardiff is the center of the universe. Partially justified, since the show is set close to a rift, one end of which is fixed on Earth while the other is apparently floating randomly through space-time. While not every alien in the show comes through the rift, it seems to act as a generalized, naturally-occurring Weirdness Magnet.
The Sarah Jane Adventures is also guilty of this, usually having international-scaled disasters that could've killed millions of peoples (remember the Horoscope Incident? It's lethalness was the polar opposite of FlashForward).
Just about every single season of Power Rangers. Early seasons at least, give lip service to Earth being an Insignificant Little Blue Planet but it doesn't really work. Justified at times, as often the threats are earth-based.
Red Dwarf also fits this trope to an almost absurd degree. The Earth is long since lost but every character is a human or robot and there are no alien species.
Inverted in Battlestar Galactica; rather than coming from Earth, the entire cast is busily trying to get there.
Maybe... "This has all happened before, and it will all happen again..."
Turns out that The Final Five Cylons were fleeing from a devastated Earth to find the mythical Twelve Colonies. Ironic, eh?
And the epilogue reveals that that planet wasn't our Earth, but quite different planet of the same name. The Colonials and their Cylon allies finally find an unnamed planet that is, according to them, filled with more life than all the Twelve Colonies put together, and inexplicably also houses primitive Homo sapiens in one of its continents. They decide to call it Earth in memory of the dream they pursued for so long. Fast-forward 150,000 years and confirm that it's indeed our very own home planet, in case the continental shapes weren't a dead giveaway, already.
Ultraman and all his successors keep coming to Earth. To be fair, the Ultramen are basically Japanese Green Lanterns. It can be assumed there are thousands of other Ultramen patrolling the rest of the universe.
The Goa'uld found Earth's native population, abducted, and enslaved them. Furthermore, much of Stargate SG-1 deals with Earth trying to defend itself from the Goa'uld coming back.
The trope is lampshaded in "Deadman Switch":
Aris Boch: Contrary to popular human belief, the Earth is not the center of the universe.
According to Stargate Atlantis, the city was built on Earth before the Ancients left for the Pegasus Galaxy. Likewise, the Wraith are interested in getting to Earth since it would be a richer feeding ground than any that they know about.
In Stargate Universe the point of origin for dialing into Destiny is not the local stargate's but Earth's. It is actually kind of justified in that Earth is the homeworld of the Ancients, who built Atlantis and Destiny. Humanity is descended from the Ancients, so that is the reason why we are on the same planet.
Averted in Andromeda (at least before the finale of Season Five, a season which had various other continuity errors as well). While Humans Are Special, Earth is an utterly unimportant backwater first overrun by the Magog and then conquered by the Nietzscheans.
Averted pretty hard in Farscape: Only Crichton cared about Earth. All the other aliens just wanted to go home, too. Of course, the Scarrans did try to invade Earth once through a wormhole, but after Crichton collapsed the wormhole, they settled for trying to conquer the rest of the galaxy. Also, Scorpius threatened to invade Earth, but said that the journey there would take decades, and he was only doing this to try and get John to cooperate with him. If anything, their ship, Moya, was the central Weirdness Magnet of the universe.
Babylon 5 plays with a variation of this. Earth is NOT the center of the universe, but, at least for the duration of the show, a space station built by Earth and crewed by Earth humans is. In fact, the Distant Finale has the station be decomissioned and blown up after it stops being the center of the universe, which has been moved to Minbar.
Parodied in a Paranoia scenario from White Dwarf magazine a long time ago. The aliens had learnt all they knew of us from watchingDoctor Who, and had come to the conclusion that the goal of all civilizations was to invade Earth. Preferably in the form of pepper-pot shaped robots who yell "EX-TER-MIN-ATE".
Plus, it has the Galaxy's richest deposits of precious zinc oxide.
And, like, you can get like two hundred pairs of designer jeans for one lousy fusion generator! Like, used, even!
Also, humanity is known to be the coolest race in the galaxy.
Played semi-straight and justified in Warhammer 40,000. Earth/Terra is the psychic beacon known as the Astronomicon, necessary for faster-than-light travel by providing a "landmark" in the Warp. If the Astronomicon didn't exist, then all ships wishing to travel through the Warp would be eaten by daemons (or worse), rather than there being just a slight chance of such horrors occurring. Terra is also the capital world of the Imperium of Mankind, the single biggest political and military force in the galaxy. Terra is also notably the site of the final and most crucial stage of the Horus Heresy, and ever since has been the most heavily fortified world in the entire Imperium - between the combined forces on Terra, Mars, and Titan, as well as the God Emperor's personal psychic might, it's virtually impossible to take over Terra, ever.
However it is only important to humans, as other factions don't require the Astronomicon for FTL travel, utilizing other methods, or particularly care about Terra and its supposed holiness.
However the Astronomicon is said to be a massive psychic magnet for the Tyranids, the extragalactic hivemind coming to devour the raw biomass of The Milky Way. In addition, the failed plan of the God Emperor of Mankind to tap into the Eldar webway in order to remove mankind's dependence on traveling through Hell Itself, has left a weakspot in the barrier between the Warp and Realspace, held shut only by the Crippled Emperor's mind.
It's also hinted, especially via Tyrannid fluff, that while Earth may be the most important world in the galaxy, the universe as a whole is a lot bigger - the light-years long hive fleets capable of consuming entire systems may only be the first probing fingers of an organism the size of galaxies which has already consumed far large and more powerful empires. The Earth seems important to humans, but to others it's just a small part of their next snack.
Because of this, the galactic map looks extremely lopsided, with the segmentums surrounding the Segmentum Solar rather small - relatively speaking - due to Sol's position in one spiral arm, and the ones to the galactic east utterly enormous.
Nothing surprising. Every big state that has both the civilizational center and the frontier has its core administrative units tiny (compare the states of New England) and its frontier units large (compare Texas or Alaska). Russia is an even better example than the USA: Krasnoyarsk Krai and Yakutia are WAY larger than Moscow Oblast.
Subverted in BattleTech — Earth is indeed pretty much the spatial center of the known universe because it's the planet mankind started out from and there are no other known intelligent species in the setting, but most of the important political and military action has moved elsewhere centuries ago and the governments of the Successor States have their seats on their own capital worlds.
However whoever controls Earth tends to be the most powerful faction.
To elaborate, Terra is the most industrialized planet in the Btech Universe, aka the Inner Sphere. To paraphrase one of the books, "Hesperus II is one of the most important manufacturing worlds in the Inner Sphere, by virtue of being home to the massive Star League era Battlemech Factory, Hesperus Industries, which supplies 40% of the Battlemechs to the Lyran Military. Terra was home to literally dozens of comparable facilities." The only reason whoever controls Terra doesn't conquer everyone else is manpower/resources. Terra has been strip-mined for every resource centuries ago, as have most habitable worlds nearby, and being the center of a fragmented galaxy, and having the 5 biggest nations all have territorial interests in the area, the core worlds are among the most heavily war-torn. And that's saying something in a galaxy that has had less than a century of peace in the last 800 years.
You'd think that Dungeons & Dragons would avoid this easily, being a fantasy RPG, but no. Two of the oldest D&D game-settings, Mystara and Oerth (get it?), have each been described as "parallel Earths", and the top-selling Forgotten Realms was named that because it'd supposedly been visited by medieval Earth folk, giving rise to our own legends of magic, dragons, unicorns and so on. A spin-off of the Ravenloft product line was called Gothic Earth, from which one of the domains of the Land of Mists was derived. Several major NPC wizards from the early Greyhawk/Oerth products made a habit of visiting Earth, and when it became necessary to hide the Mace of St. Cuthbert from hostile forces, it was sent off-world and concealed in London's British Museum. The last one ties into legends that St Cuthbert was a mortal from "another reality" - the Genius Bonus being that Cuthburt of Lindisfarne was a real British saint.
The Star*Drive setting has Earth (or the Sol System) at more or less the geographic center of Known Space. Humans branched out in all directions from there.
More or less literally true in Rifts. The Coming of the Rifts turned Earth into a multi-dimensionalMegaversal focal point. Just about any place in the Megaverse can be reached from Earth, making it a very attractive target for just about every world conqueror/dimensional traveler. The reason it hasn't been taken over by alien forces yet is not due so much to scrappy humans as the fact that it's a very very very dangerous and unpredictable place, and there are so many different groups vying for dominance that none have managed to come out on top yet.
Interestingly used in Magic: The Gathering TCG, it is explained that there's a multiverse consisting in several planes (read: universes), in each plane there is a maximum of one planet able to sustain life, that planet serves as "earth" for this trope's purposes. This was played straight for the first part of Magic's history, in which it was established that multiple planes existed, but almost all blocks were set on the same one, called Dominaria. Mirrodin was the first block not set there since Homelands, seven years earlier, and several pre-Homelands blocks were set on Dominaria as well. Some non-Dominaria worlds were seen in the meantime, but they were rarely the center of the action or the home worlds of the main characters.
The Super Robot Wars series is absolutely riddled with this trope, as most of the games include quite a few series where this sort of thing is going on, all at once - so it's not unusual to have six or seven different alien species invading Earth at the same time.
Seems to be implied in Mass Effect, where Earth isn't the center of the universe... yet. Humanity has been on the galactic stage for a far shorter time than anyone else - less than thirty years - but as the game opens, they're already a major political force, poised to get a representative on the ruling Council in short order. Races that have been at it for far longer without any of the success cannot believe humanity's sheer aptitude for politics. Reaction is split pretty evenly between bitterness and awe, but it's clear that the galaxy has simply never seen a race this intent on running things before.
However, the reason for the drive for colonization was because the Earth was once badly overpopulated and polluted, and they needed to in order to prevent the Earth form become Earth That Was.
In the actual game there's a total of one mission in the entire game taking place in our solar system; yet the only body you land on is the Moon. It's the quest you have to take in order to open your specialization talents (e.g., a Soldier can become either a Commando or a Shock Trooper).
Played straight in Mass Effect 3. Shepard's heroics have put their species at the top of the Reapers' hit list, so they focus on humans as soon as they arrive (after making short work of the batarians, who were basically in their way). Earth isn't the only "home-world" to fall, but it's where the game begins and ends - the Reapers even move the Citadel there after capturing it.
Rather justified in Halo. The Forerunners intended for humans to inherit their technology and accordingly programmed all their facilities to recognize all humans (and only humans) to have full system access. It's also the reason the portal to the primary hub of the Halo network is located in East Africa, right in the region inhabited by early hominids during the time it was build.
Earth doesn't exist in the WarCraft series, but there, Azeroth is the center of the universe. Only one other planet has ever been visited in the games, and it's a Shattered World, torn apart as a side effect of one of the many conflicts Azeroth has withstoodjust within the past generation. But we know that many other worlds exist, and every named one is a Throwaway Country. Argus and probably Xoroth were conquered by the Burning Legion, K'aresh was conquered by a different kind of demon, we're told that the Titans have created or remodeled countless worlds as a matter of course and the Burning Legion in turn has destroyed countless, the Old Gods are imprisoned on Azeroth and have some kind of influence on Draenor as well... but the intelligent life on Azeroth has survived attacks by all of the above and more.
Played with in Master of Orion. Where players start is random, but the star-system at the center of the galaxy is always the titular Orion.
The D'ni from the Myst games could have linking-book access to virtually any sort of world their writers could dream up, with no regard for distances and little even for the laws of physics. Guess which planet they decided to settle down on (well, in) and found their capital city.
Dragon Ball Multiverse: It's so subtle that it can be missed, but it's there. When the Vargas arrive to Universe 18, the very first thing they do is checking Earth. The reason? It seems to be a magnet for the most powerful warriors across many different universes. Six different universes (3, 9, 12, 14, 16 and 18) had at least one of its members coming from Earth.
Played somewhat straight early on in the backstory of Tech Infantry, due to its origins as a fan-made expansion pack for the Old World of Darkness games. Since reality is shaped and created by the collective conscious and unconscious beliefs of humankind, Earth is in a very real sense the central, most important place in the universe. Later in the game story, however, Earth is repeatedly devastated and eventually effectively destroyed and becomes an uninhabited backwater system, even for humans.
In Dominion And Duchy it looks like Earth is extremely minor, but then its discovered that Earth was the source of the extremely nasty Imperium of Humanity that was engaged in a universe-wide war.
In Orion's Arm Earth is the physical center of the Terragen Bubble but otherwise little more than a historical landmark.
The reason for so many aliens coming to Earth in Ben 10 is the show's MacGuffin: the Omnitrix. However, the film "Secret of the Omnitrix" suggests another reason: the majority of aliens within the universe find humans quite tasty.
Even though interstellar travel is commonplace and it's known that there are colonies and settlements throughout the galaxy, the Earth is still treated as the whole world in Futurama. When it's conquered and/or destroyed, the characters treat it as if the whole universe has ended, such as in "In-A-Gadda-Da-Leela", when Leela's shown an image of Earth exploding, she laments that she and Zapp are "the last humans left in the Universe," despite knowing, for instance, that Amy Wong's parents and others live on Mars.
I'd definitely watch a show set on the Harlem Globetrotters homeworld instead.
Dr Zoidberg allegedly doesn't know anything about humans because he "specializes" in alien biology. "Alien" meaning anything from the bazillions of other populated planets that aren't Earth. This is especially bizarre considering Zoidberg is himself an alien from the planet Decapod, so humans should be aliens to him.
The thing with Zoidberg is that when they say he specializes in Weird Alien Biology, it's likely that human biology not being weird is why he's so terrible at it.
Lots in the Legion of Super Heroes cartoon. Zix shows up there, with no reason as to why. The most glaring example is when Cosmic Boy, Saturn Girl and Lightning Lad are all aboard the same ship headed for Earth. When they suddenly decide to set up the Legion, they put HQ on Earth - with no explanation as to the original reason they were headed there. Presumably Earth really is the centre of the universe, or at least a really popular place for fortune-seekers.
Lilo & Stitch demonstrates this perfectly. An intergalactic criminal is put on trial and given his sentence. When one of his experiments (626, AKA the eponymous Stitch) escapes containment, the galactic conference watches in awe as his torn-up ship descends on a certain planet in a certain solar system.
Transformers, under any and all possible circumstances, will land on Earth looking for whatever drives the plot at that point. If they aren't on Earth, they're back home on Cybertron. Sure, they go other places too, but anywhere else is just a pit stop, Earth is the only other planet they stay on.
Subverted and then played straight in the comics from IDW. Earth is just another planet where the Autobots are trying to protect the native populace from the Decepticons without being caught...but the discovery of a super-energy source brings notable Transformers from both sides, including the leaders of both factions, to Earth, the standard protocols being skipped over entirely.
It is heavily suggested, though, that the super energy source is only present because Earth was one of many planets the Decepticon Shockwave seeded with it sometime in the past. Earth wasn't supposed to be unique in having this energy source, it's just that Shockwave only got to make his follow-up trip to stabilize it to Earth before getting rudely interrupted by the Dynobots.
Also partially subverted in Transformers Cybertron. While the first Cyber Planet Key and the Omega Lock were on Earth, the majority of the series was spent planet-hopping trying to get the rest of the Cyber Planet Keys together and save Cybertron.
This was toyed around with in Beast Wars, as the Maximals and Predacons don't know what planet they crash landed on. Yeah Megatron was aiming for Earth, but there are two moons. Dinobot defects thanks to this. Actually, they got the right place. But not the right time. Oops!
Actually the plot was to travel to some point in the past and off Optimus Prime while in stasis lock. It would have went off without a hitch had it not been for Optimus Primal and the fact that the Vok were messing around in Earth's primordial past.
Transformers Prime continues this tradition, with Earth having stores of Dark Energon, sleeping warriors, and, at one point, visitation from Ancient Cybertronians. However, there is a rather dark justification for this: Earth is actually Unicron's dormant body.
It is also where the lost Iacon artifacts were all hidden.
Megatron puts the conquest of Earth on equal priority with restoring Cybertron after learning the above, believing that the destinies of the two worlds have always been intertwined. To control one without controlling the other is to control nothing at all.
Earth is the centre of the visible universe. This is not a reflection of its cosmic status, however. It's just the point the observation is being done from. Beyond the visible universe is just too far to see, limited by speed of light. Confusingly, despite the universe being ~13 billion years old the observable universe has a radius closer to ~45 billion light years and the radius of the actual universe is even bigger. Something to do with how the expansion of space-time isn't limited by the speed of light. Hopefully someone who gets it will come along and explain. It's a consequence of Hubble's Law, that the further two bodies in the expanding universe are from each other the faster they are moving away from each other (or, more precisely, the faster the amount space in between them is expanding). The horizon of the observable universe is the distance at which that point in space is moving away from us faster than the speed of light, so that no light originating beyond that point can ever reach us.
The official system of galactic coordinates used by NASA uses the Sun as its centre point.
Are the planetary systems beyond our own called planetary systems or stellar systems? Nope, they're most often called solar systems, after Sol. Similar to how moons are named after the Moon. This is actually a consequence of neither the Sun nor the Moon having been named. Even the terms Sol and Luna just mean the Sun and the Moon in Latin. Calling other bodies solar systems is just as valid as calling them sun systems or calling their closest stellar neighbor a sun.
The literal interpretation of this trope was the accepted scientific view of the universe up until the 16th century, when people started thinking the Sun was the centre of the universe, and that was discredited over time when people started realizing that the stars were also suns in their own right and no star had a privileged position, about the 20th century or so. Note that this is not as egocentric as it sounds and is often made out to be. In the old geocentric cosmology, gravity pointed to the center of the universe and there only. Earth was the "off-scourings of creation," at the _bottom_ of the universe, sort of like a cellar or dungeon.
Then there's the really bad joke that "if the universe is infinite in all directions, then I am the center of the universe". Once upon a time, a king asked a wise man to tell him where the center of the world was. The wise man pointed to a spot on the floor and said, "It's right here. If you don't believe me, go ahead and measure it."
There is an entire subset of astronomers that actually use this as a valid explanation for everything they can. Be it the lack of quasars in a large radius around us, or the fact that the galaxy is contracting inward, they jump to the conclusion it must be we're in a special spot. Of course, then other astronomers come up with more logical explanations, often the "point of observation" effect mentioned above. One theory even posited that we were the center of the universe, until another proposed that everything was. This may have an interesting message.
Quick, name every planet in the universe known to have sentient life. Done already? The operative words of course being, once again, "known to be" — and then specifically known as such by all of one single species among the diverse inhabitants of said planet, at that. Of course, most humans being human...