Earth (or another species' homeworld) has fallen victim to some disaster and is no longer inhabitable. But fear not, we managed to get some people off before it was too late. The actual means of escape will usually be some form of The Ark
For some reason this seems to be the sole reason for interstellar colonization in most "mainstream" sci-fi.
Always results in a case of Earth That Was
, though in some cases of that trope the space colonies existed before the disaster. For when the survivors already happened to be in space for unrelated reasons, see But What About the Astronauts?
Anime and Manga
- The Authority do this in one arc, evacuating the planet's entire population so as to cause less collateral damage when fighting a superpowered villain.
- WALL•E: Humanity relocates to ships like the Axiom for 700 years.
- In Titan A.E., the alien Drej vaporize Earth in the opening sequence while refugee ships try to escape.
- In Battle for Terra, Earth, Mars and Venus have all been blown up, so humans go to the eponymous planet to find a new home.
- Oblivion has humanity attempting to escape a ruined Earth that has been wrecked during an Alien Invasion war, settling a new colony on Titan. Of course, this is a big damn lie, but saying any further details is a massive spoiler.
- In the live-action Transformers film Cybertron was destroyed in the Autobot / Decepticon war and they search for the Allspark in order to rebuild it.
- In the 2009 Star Trek movie, the planet Vulcan kicks the bucket, and at the end of the move, Spock Prime considers it his mission to help the remaining Vulcans establishing a new home world.
- The sequel reveals that New Vulcan has been established.
- In Jason X, humanity left Earth due to pollution and has resettled on a new planet called Earth Two.
- At the start of Man of Steel, Krypton is about to implode. Jor-El's pleas to evacuate Kryptonians falls on deaf ears, as no one believes that their planet is dying. However, General Zod believes Jor-El but only wants to save the elite bloodlines. Jor-El, instead, decides to only save his infant son.
- Mission to Mars shows a holographic recording of Martians evacuating their planet for a distant galaxy en masse aftera meteor strike renders the planet lifeless, except for a lone ship heading for Earth to seed it with life.
- Earth is polluted and overpopulated in Red Planet. Humanity's only hope is to terraform Mars and re-settle everybody there. The mission is sent to determine why terraforming is failing. At the end, it's implied that the terraforming and re-settlement project will be scrapped in an attempt to replenish the dwindling levels of oxygen on Earth using the oxygen-producing bugs found on Mars.
- After Earth, as the name implies, takes place in the distant future after humanity evacuated the now deadly Earth.
Live Action TV
- In Last and First Men the Fifth Men migrate to Venus when the Moon (destabilized millions of years earlier in the Martian/Second Men war) starts to crash into the Earth. And the eighth men design the ninth to colonize Neptune when the sun expands to cover the Inner System. But eventually the sun goes nova too quickly for the Eighteenth Men to devise a means of escaping to another system, though they do manage to send out "seeds" of life that might eventually evolve into new humans.
- In the "Homecoming Saga", a series of 5 novels by Orson Scott Card, the Earth was rendered uninhabitable by human wars, and mankind departed for Harmony, as well as at least forty other planets.
- In Walter Jon Williams' Aristoi, Earth was destroyed by Grey Goo, leading to the reorganization of society into essentially a confederation of feudal states, with each state's leader (the Aristoi in question) being the only ones allowed to use nanotechnology freely.
- Arthur C. Clarke's Rescue Party has aliens coming to Earth in order to try saving at least a few humans before the Sun goes nova. In the end, it turns out the humans built a fleet and left already.
- Robert Sheckley has a story with an amnesiac human waking up on a starship, apparently the last survivor after a nova. The ending reveals he serves as a Neuro-Vault for the entire humanity.
- Gianni Rodari has two short stories about aliens from a threatened planet settling on Earth.
- Isaac Asimov's The Currents of Space end with a planet (not Earth) being evacuated - its sun is about to go nova.
- In the Isaac Asimov book Robots and Empire which links his Robots series to the Foundation series, a robot causes/allows a radioactive explosion which will slowly poison Earth, forcing the population to expand out into space.
- Happens twice in the Noon Universe:
- The premise of Space Mowgli is that Terrans intend to evacuate the Human Aliens of the planet Panta, whose sun is about to explode, to the planet Ark (named after Noah's Ark).
- In Beetle in the Anthill, the scientists speculate that the entire population of Hope (the planet Abalkin explores in the flashbacks) was evacuated to another (unknown) planet by the Wanderers.
- The Insects From Shaggai (AKA Shan) in Ramsey Campbell's Cthulhu Mythos stories. When their home planet was destroyed by a Mythos abomination, some of them fled to a succession of other planets, finally ending up on Earth.
- In the backstory to the Gor series the Kurii destroyed their homeworld in intercine battles, so they went looking for a new home and found Earth & Gor. The Priest-Kings have waged a war against the Kurii to keep them out for millenia, all unseen by most humans.
- The Yuuzhan Vong of the New Jedi Order series underwent a home galaxy evacuation, after massive wars of conquest and then internicine wars they started devastated so much of it that it was rendered incapable of sustaining their civilization (their actual homeworld was destroyed first, and it's speculated, though not fully confirmed, that they were the ones who did it). After travelling through the intergalactic void for milennia, they finally found the Star Wars galaxy- and decided to take over.
- It has also been speculated that they were fleeing the Silentium-Abominor War, which would explain their belief that technology is unholy.
- In The Hitchhiker's Guide to the Galaxy the colonists aboard the Golgafrincham B Ark were tricked into believing that they were part of one of these, though everyone had heard a different story of what doom was facing Golgafrincha, moon crashing into the planet, planet crashing into the sun, ravenous mutant star goat, etc. The reality was that the B Ark was composed of the "useless" third of the population (telephone sanitizers, hairdressers, middle managers...) and the rest of the planet was getting rid of them.
- Somewhat inverted in Battlestar Galactica (Classic) and Battlestar Galactica (Reimagined), the twelve colonies of Kobol are being evacuated and searching for Earth, which is the "lost" thirteenth colony.
- A surprisingly consistent point of future history in Doctor Who foretells the mass evacuation of Earth around the thirtieth century, to avoid solar flares. The Eleventh meets the Starship UK in "The Beast Below", but it comes up in other episodes as well. In addition the fourth Doctor encounters a wheel-type space station full of sleepers in "The Ark In Space", which is set 20,000 years in the future implying that it happens more than once.
- The National Geographic special Evacuation Earth has as its premise a wayward neutron star heading towards Earth and attempts to build a Generation Ship to take 250,000 people to Bernard's Star.
- In Defiance the Votan Collective came to Earth when a supernova destroyed their home system.
- On the Planet of the Week in the Stargate SG-1 episode "Lifeboat" SG-1 finds a crashed Sleeper Starship built by a human society called the Talthuns, who had evacuated as many people as possible before their planet was destroyed by a coronal mass ejection caused by a "dark star".
- In the Babylon 5 episode "The Deconstruction of Falling Stars", which flashes forward to different eras of humanity's future after the show's time frame, it is shown that humans evacuate Earth one million years in the future, before an impending mysterious artificially-induced nova explosion of Sol.
- Star Trek: The Original Series episode "The Empath". The star of the Minarva system is about to go nova. A group of highly advanced aliens known as the Vians can save the population of only one of the planets in the system. They decide to determine which planet's population will be saved by putting a member of each population through a Secret Test.
- In The Event, it's eventually revealed that the Human Aliens are planning on evacuating their 2 billion population to Earth, as their star is about to make their planet uninhabitable... and are willing to commit genocide to make space for their people.
- In an early episode of First Wave, Joshua reveals that the Gua homeworld is dying, and the conquest of Earth is primarily meant to allow the Gua to re-settle here.
- Peter Schilling's "The Noah Plan": The Earth's orbit decays as it drifts towards the sun, and the people on Earth prepare for evacuation by "returning to the universe".
- During The Fall in Eclipse Phase millions of people uploaded their Egos to the sparsely-populated colonies in other parts of the solar system (uploading being the easiest means of space travel), while some others crowded the Space Elevators and crammed aboard ships.
- Classic Traveller, Double Adventure "The Chamax Plague/Horde". In the Back Story, the alien population of a planet was close to being wiped out by a Super-Persistent Predator species called the Chamax. They decided their only chance was to build a fleet of Sleeper Starships to carry all of the remaining aliens to other star systems.
- BIONICLE: In the Kingdom Alternate Dimension, Matoro fails to revive the Great Spirit Mata Nui, leaving the Matoran Universe in danger and prompt mass exodus onto the island of Mata Nui. Not all beings made it safely, but while many made it to the island, it is only a temporary refuge. The survivors settled quickly and also planned on how to leave the island for the stars.
- Homeworld: The Mothership was meant to be a colony ship before the Kushan even were aware of the threat to their existence, but when the Taiidan incinerated Kharak's atmosphere it became necessary to their survival as a species.
- Earth, or Lost Jerusalem as it's called, is referred to often in Xenosaga. Humans had to leave it because of a mysterious space-time disturbance. Its location has been long lost. At the end of the third game a chunk of the party goes off searching for it, and we're left wanting another sequel.
- The backstory for its spiritual prequel, Xenogears, is similar. Humans left Earth in AD 2510 due to a space-time anomaly. The only reference to Earth in the game, though, is in the intro, and it is called "the main planet."
- In Outpost 2 the human race has fled from an asteroid-doomed Earth. The plot of the game revolves around the earthling colonists of a new planet and how they destroy themselves all over again.
- Another non-Earth example: The D'ni of the Myst series originated on a world called Garternay, which became uninhabitable when its sun began growing dim. Their ancestors fled into a succession of other worlds via their linking books, and have since lost all contact with their abandoned homeworld.
- In SimEarth, if the sapient civilization develops past the "nanotech age", an event called "the exodus" is triggered. All cities, regardless of tech level, are fitted with engines and take off into space. The planet is declared a preserve and left alone, possibly allowing a new sapient species to evolve. The motivation for the exodus is unclear.
- In the RTS Earth2150, this is the ultimate goal of all three factions, on account of the imminent Earth-Shattering Kaboom. Throughout the campaigns, you not only have to complete missions to cripple your rivals, but stockpile your excess resources in order to build a colony ship to carry you to another world before the countdown expires.
- In Mass Effect:
- This is a common last resort for species attempting to survive a Reaper invasion. Of particular note is a Side Quest to save the Elcor, whose homeworld is being assaulted, in Mass Effect 3. However, this only serves to delay the inevitable, because the Reapers are patient enough to spend centuries exterminating every last trace of all sapient life, no matter where they hide.
- Before the story proper, the quarian race escaped their homeworld to avoid being exterminated by the robot race they created, the geth. Worthy of note is that the geth allowed them to leave to avoid committing genocide.
- Also before the series proper, the drell were rescued from an overpopulated homeworld by the hanar, and felt indebted enough to work as their agents, laborers and assassins, of their own free will. The only downside is that moving from a nearly-desert world to one that's 90% ocean had horrible results on their health - any drell that spends more than a short time outside of their highly-maintained city contracts a terminal lung disease.
- Freespace: The Vasudan homeworld starts an evacuation partway through the game as the Shivans draw near. Though quite a number escape, the Shivans arrive before they're done and four billion Vasudans die when the homeworld is subjected to Orbital Bombardment. In the sequel, Vasuda Prime is still uninhabitable.
- In Orion's Arm Old Earth suffered a Grey Goo outbreak known as the Nanodisaster, but that's not why it was evacuated. The outbreak was nullified by an AI named GAIA and e decided humans were the worst threat to Earth so e told us to leave, before e sicced eir nanoswarms on us. E was considerate enough to build a fleet of ships first though.
- The Simpsons Treehouse of Horror has 2 ships to leave the earth with various stars. One goes to Mars, and the other to the Sun.
- A staple of the Transformers series.
- In Generation 1, the Autobot evacuate Cybertron as it has run out of Energon to support life.
- In Transformers Prime, the Autobots and Decepticons fled Cybertron when it became unsuitable to support them.
- In Superman: The Animated Series, Jor-El had a practical plan to evacuate the entire population of Krypton before it exploded: cast everyone into the Phantom Zone, have someone travel to a suitable planet and release them. However, the thought of being stored with the worse criminals of Krypton and Brainiac's self-serving lies made sure it wouldn't be used.