Solar System Neighbors

The search for life beyond the planet often takes looking beyond the Sun's reach, to distant stars. But sometimes extraterrestrials are a lot close than even the nearest stars, and you only need to look within the Solar System itself for them. Perhaps the Once-Green Mars still has some greenery, or Venus Is Wet. Maybe one of the other moons or planets are inhabited. In short, Earth isn't as lonely as it thinks it is.

Because the different bodies in the solar system are well-understood, don't expect this to show up in hard science fiction, unless you're dealing with some extinct race or Extremophile Lifeforms who can handle the more extreme conditions. In Real Life, astronomers are interested in worlds like Mars and Europa for the potential they may have harbored life, and may still do. It'd almost certainly be microbial, but it would at least show that life is more likely to arise in the universe than previously thought. It's more often seen in Planetary Romance stories.

Earlier stories from before space probes were sent to investigate Venus and Mars have them as popular hosts for aliens, due the former's similar size to Earth suggesting it could have life (usually in a humid jungle due to being closer to the sun) and the latter thought to have had canals due to an optical illusion.

This is not a case of Colonized Solar System. This is when worlds other than Earth in the Solar System have developed their own form of life. Super-trope of Lunarians, for extraterrestrials from Earth's own moon, and Martians, for extraterrestrials from the red planet. Fictional planets on the other side of the Sun go under Counter-Earth.

Examples

Multiple worlds

Comic Books

• The DCU:
  • All-Star Comics: In issue 13, each member of The Justice Society of America is knocked out and sent to a different planet in the solar system. All of them encounter intelligent life on their respective planets, with Dr. Mid-Nite lampshading how improbable it is to find life on even one other planet. This occasion is actually when Wonder Woman first met and befriended Queen Desira of the winged women of Venus.
  • Martian Manhunter: J'emm, Son of Saturn is part of a race descended from Martian colonists. Though referred to as Saturnians, they technically inhabit the planet's various moons.
  • Pre-Crisis Superman comics had all nine planets of the solar system inhabited by at least one race.
  • Wonder Woman Vol 1: Wonder Woman becomes fast friends with the winged Queen of Venus, gains a nemesis in Mars who rules the ethereal Martians, fights and then becomes allies with the Emperor of Saturn, rescues an abducted woman from Pluto, and alongside the Venusians overthrows the despotic misandrist Queen of Mercury. Earth is also invaded by a group from Neptune.
• The League of Extraordinary Gentlemen, being a Massive Multiplayer Crossover which treats various Planetary Romances as canon, has a lot of the solar system inhabited;
  • Green and Red Martians, Sorns, Hither People and the Martian Manhunter. The The War of the Worlds (1898) Martians appear as extraplanetary invaders before giving up and turning to Earth.
  • The Moon has Amazon Women on the Moon at war with the Selenites with gravity and air generated by Monoliths. The Clangers and the Soup Dragon live there as well as Lucien and Uatu The Watcher.
  • Venus has The Treens.
  • Mercury has Jack Flash's race of Human Aliens.
• Scarlet Traces is similar to The League of Extraordinary Gentlemen;
  • Mercury has Mercurians and Treens from Dan Dare.
  • Likewise Venus has Treens and Therons.
  • The Moon has Selenites and Uatu The Watcher.
  • Mars has Green Martians from John Carter and Hrossa and Sorns from Out Of Silent Planet. Not forgetting the The War of the Worlds (1898) Martians that the series revolves around.
• Italian anthology comic Maledetta Galassia ("Accursed Galaxy") starts with an affectionate shout-out to pulp-era sci-fi comics, and its use of this trope.
  Back then, every planet in the Solar System was inhabited. There was an ancient dying civilization on Mars, a people at the dawn of prehistory on Venus, mysterious shadow beings on Uranus, and the bad guys — for some reason — were always on Jupiter.

Fan Works

• Rocketship Voyager is Star Trek: Voyager written In the Style of a 1950s sci-fi short story. Earth, Venus and Mars are joined in the Tri-World Federation, designed to give the latter two worlds equal political and military status with humanity so they won't be overwhelmed by an overpopulated and expansionist Earth. Venerians are a primitive matriarchal Proud Warrior Race, while Martians are the equivalent of Vulcans (with some Ray Bradbury influence). There are also the (unseen) Jovians who live in the upper atmosphere of Jupiter.

Film — Live-Action

• Abbott And Costello Go To Mars: The rocket is designed to take its crew to either Mars or Venus, the two planets closest to Earth. The scientists end up deciding to send it to Mars, but once it actually blasts off the second time, the ship ends up on Venus instead.

Literature

• Alan Mendelsohn, the Boy from Mars features aliens from Mars and Venus, and residents of other solar system planets are mentioned in passing. They're all Human Aliens who are able to use interdimensional travel to planet-hop, and exist largely undetected amidst Earth's general population, who seemingly live on normal 70s Earth.
• Half Breed, by Isaac Asimov, has human-Martian hybrids at its focus. The sequel Half Breeds on Venus takes the action to a habitable Venus.
• In the 1944 short story "Desertion" by Clifford Simak, there is apparently life all over the Solar System, a fact which humans have been exploiting by artificially converting themselves into native lifeforms; it's stated that they have already taken over several planets this way (the moral and ethical issues aren't brought up). However, when they do so on Jupiter, the converted volunteers head off and never come back. Everyone assumes they've died somehow, but it turns out that Jovian "Lopers" are vastly physically and mentally superior to humans; having considered their former lives from their newly-gained perspective, they can't bear the thought of becoming human again.
• Edison's Conquest of Mars, an unauthorized sequel to The War of the Worlds (1898), has the Martians return in conflict not just with Earth, but also with giant beings from the dwarf planet (then considered an asteroid) Ceres. Their size comes from the very low gravity of Ceres.
• Pretty much every planet in Earth's Solar System — as well as the Sun, Earth's Moon and Titan — in Emperor Mollusk versus The Sinister Brain are populated with intelligent life. Earth seemed to have been the only planet that hadn't yet mastered space-travel before Mollusk took it over.
• Last and First Men: The Second Men get into a millennia-long war with sapient bacterial clouds from Mars that ends with the extinction of both species, Mars scoured of all life, and the Moon sent on a collision course with Earth millions of years later. When the Fifth Men notice the Moon coming down on them they emigrate to Venus and begin terraforming, only to discover a sapient species under the oceans that lives off radioactive volatiles in the crust and is killed by oxygen, but too late to stop the terraforming process.
• The Triplanetary briefly shows Martians and Venusians, who look mostly human in sharp contrast with the exosolar Arisians that show up a few chapters in. There’s also mention of Jovians who were apparently wiped out in The Great Offscreen War. In the sequel “First Lensman” it’s shown that Pluto was colonized by the exosolar Palainians long before Earth (Tellus) discovered space travel.
• The John Carter of Mars series holds that much of the Solar System is inhabited, from the red and green Barsoomians of Mars to the Tarids of Thuria (Phobos) to the Skeleton Men of Jupiter.
• Nearly the entire rogues gallery of Ricky Ricotta's Mighty Robot (with the exception of Dr. McNasty from the first book) are aliens from each of the Solar System's planets, and each of them invade Earth because of some aspect of their homeworlds that they do not like and want a better home.
• The Space Trilogy is a Science Fantasy by C. S. Lewis wherein a number of planets are inhabited. The Earth is cut off from them because it is tainted by sin. The other worlds' inhabitants are Human Aliens.

Live-Action TV

• In Space Cases, the inhabitants of Saturn, Mercury, and Uranus are all descended from a common humanoid ancestor who colonized all three planets.

Tabletop Games

• In Space 1889 most of the inner planets are inhabited.
  • Mercury has a primitive race resembling crabs with ammonia-based biochemistry on the dark side.
  • Venus is home to stone age lizardmen.
  • Luna has underground-dwelling insectoid natives who were enslaved by Russia.
  • Mars is home to at least three sapient species. The city-dwelling Canal Martians who are roughly Renaissance-level but were once more advanced than (Victorian) humanity, nomadic Hill Martians, and flying mountain-dwelling High Martians.
• Pathfinder introduced an entire solar system to play around with in its "Distant Worlds" campaign setting. Based heavily on old Planetary Romance ideas of the other planets in our own solar system, the entire system is brimming with intelligent species to play as and alien monsters to fight.
• In Rocket Age, almost every planet in the solar system and a large number of large moons are all inhabited. The ones that get the most play are Mars, Venus and the moons of Jupiter.
• Starfinder took the same setting and advanced it by several thousand years into a full-blown Space Opera setting. The various worlds have come together as The Pact Worlds, an interplanetary alliance that allows free enterprise and collective security between them. Every planet has its own unique endemic species of intelligent aliens, from the mechanical anacites of Aballon, to the lashuntas of Castrovel, to the undead elebrians of Eox.
• In the Urban Jungle supplement Astounding Science every planet in the solar system is inhabited, with Jupiter and Uranus having solid surfaces under the clouds and Neptune an ocean, though Saturn instead has an oxygen atmosphere around its rings. There's also a Counter-Earth called Telluria.

Web Original

• The Thrilling Adventure Hour: A featured segment is "Sparks Nevada: Marshal on Mars", which is a Space Cowboy adventure featureing the eponymous marshal and his Tonto-esque native Martian (or "Marjun") companion Croach the Tracker, who proudly declares himself to be from G'loot Praktaw, "Which you designate Mars". Also in this series, Jupiter is home to a race of Voluntary Shapeshifting aliens who ostensibly act as spies, but mostly just act as a nuisance.

Western Animation

• No prizes for guessing what the Biker Mice from Mars find on Titan in the episode "Surfer Cats of Saturn", though they're a splinter group from the extrasolar Catalonians.
• Futurama:
  • In "The Inhuman Torch", after the Planet Express crew harvest the Sun for helium, a criminal flame called Flamo hitches a ride to try and turn the Earth into a miniature star. His race are living solar energy that dwell from the Sun, and members of his race come back at the end to arrest Flamo.
  • The alien Blobs were heavily implied to come from Venus, due to one of the blobs featuring in the Venus de Venus picture, before being confirmed as such in the licensed puzzle game Game of Drones.
  • The Native Martians are essentially pastiches of Native Americans, from whom the Wong family bought the planet for a "bead" which turned out to be a giant diamond valuable enough for them to buy a new planet.
  • The Neptunians, four-armed purple aliens, come from the planet Neptune. Robot Santa Claus has forced some of them to work on the planet's north pole as Christmas Elves, where they've become undersized from malnourishment. The planet is depicted as a solid world instead of the gas giant it is in real life, and whether or not it was terraformed to be like that by the 30th century is never stated.

Venusians

Comic Books

• The DCU:
  • Sensation Comics Featuring Wonder Woman: In "Venus Rising", Diana accompanies a scientific expedition to Venus, where she and the scientists are surprised to find giant dragon-like living gasbags which seem intent on tearing apart their vessel.
  • Shazam!: The villain Mister Mind came from Venus. While he looks like a Literal Bookworm (complete with spectacles), he's one of the more serious villains in Billy Batson's rogues gallery, being an alien conqueror. He was introduced before the Venera Program debunked Venus as a habitable world, but even Post-Crisis his home world remained the same and he got off-world by stowing away in a space probe.

Comic Strips

• Safe Haven: Venus is the original homeworld of merfolk. They came to Earth when Venus began undergoing its uninhabitable climate change, and modern merfolk descend from those left behind when the rest left after deciding Earth was too dangerous.
• Dan Dare features Venus and Venusians heavily, including the reoccurring villain Mekon.

Film — Live-Action

• Abbott And Costello Go To Mars, despite the title, is actually the crew going to Venus to meet space women.
• Ghidorah, the Three-Headed Monster: Thousands of years ago, Venus had a thriving ecosphere and advanced civilization until King Ghidorah arrived there, wiping out all life. A small number of Venusians managed to survive by fleeing to Earth, where they intermingled with the native humans. In the US dub, references to Venus were swapped with Mars.
• The alien from It Conquered the World came from Venus. Physically it resembles a teepee or space pickle.
• 20 Million Miles to Earth: A manned expedition to Venus returns with an egg that soon hatches into a sulphur-eating reptilian Venusian known as Ymir. Ymir grows rapidly in Earth's oxygen-rich atmosphere, but despite his size and fearsome appearance, he's actually a Gentle Giant. Too bad those darn humans had to keep provoking him...

Literature

• The Amtor series is about an amateur rocketeer who accidentally winds up on Venus (he was trying to go to Mars/Barsoom, but passed too close to the Moon, which threw him wildly off course), living among the natives as an air pirate.
• The Weapon Too Dreadful to Use was a very early story by Isaac Asimov reprinted in The Early Asimov about humans oppressing native Venusians. The Venusians have their own method of resisting, with the titular weapon too dreadful to use.
• The Doctor Who Missing Adventures novel Venusian Lullaby features a civilisation of Starfish Aliens on Venus. Since it's set a couple of bullion years in the past, it's a bit more plausible than it would be today.

Other Planets

Comic Books

• The DCU:
  • Action Comics:
    • During the course of his job as a Planeteer, Tommy Tomorrow helps out some Jovians on Jupiter.
    • Giovanni Zatara once thwarted a planned Saturnian invasion by tricking the shapeshifting Saturnians into thinking magical powers like his own were commonplace on earth.
  • All-Star Squadron: In the Post-Crisis continuity, Starman (Ted Knight) was revealed to have traveled via hyperspace to the Jupiter of another dimension, where the locals were Mechanical Lifeforms like in his native universe of Earth-Two but much more friendly and fascinated by earth cultures.
  • DC One Million reveals that Neptune eventually developed aquatic life, and that aquatic life from other planets including Atlanteans of Earth have moved there due to the peaceful idyllic quality of life on the planet.
  • In the early 1940s, Hawkman came across a crashed ship from Neptune on Earth. Everyone on board were giants who had perished in the crash and the egg he looted from the debris ended up in the hands of an evil scientist. Hawkman fought the boy who hatched from the egg to the youth's death.
  • Justice Society of America: The Golden Age story "Vampires of the Void" features the inhabitants of Jupiter, metallic life forms who come to Earth and actually consume metal as food. They end up taking on the characteristics of the metal they eat, which is how the various JSA members are able to defeat them.
  • Shazam!: In Captain Marvel Adventures of the 1940s, the titular hero discovers that the natives of Saturn are being enslaved by extra-solar invaders and travels to the planet to expel the would-be conquerors.
  • In Wow Comics (a Golden Age Fawcett Comics publication later purchased by DC Comics), Atom Blake had several adventures on the planet Mercury where the locals were small bug-like telepathic beings.
• Marvel Universe:
  • The 1950s hero Marvel Boy (now the Uranian of Agents of Atlas) is a human raised on Uranus who fights crime using a pair of energy-projecting wristbands made from highly advanced Uranian technology. This was later retconned so that the Uranians were not actually native to the planet, but rather Eternals who had migrated from Earth to Uranus millennia ago.
  • In the very first The Mighty Thor story, Dr. Donald Blake was visiting Norway when the arrival of the Stone Men of Saturn drives him to hide in a cave, where he finds a wooden stick which transforms into Thor's magic hammer, Mjölnir... and the rest is history. The Stone Men have since been retconned to be from outside our solar system and to have only had a base on one of Saturn's moons.

Live Action TV

• ALF: Alf himself mentions that Jupiter is inhabited and apparently an important milk producers on the Universe, or that's what they say in their publicity.

Literature

• Animorphs: In Megamorphs #1, the Yeerks unleash an animal from Saturn called a Veleek, which resembles a cloud of dust and is made up of billions of tiny insect-like creatures.
• Ben Bova: Jupiter has astrophysicist go to Jupiter, with the conservative "New Reality" religious organization not wanting complex life to be discovered. They're ultimately disproven with the discovery of the Leviathan, some sort of Space Whale.
• The Sirens of Titan has strange organisms called "Harmoniums" who cling in the caves of Mercury. It's worth noting this was written back when Mercury was thought to be tidally locked.
• In Venus Prime, Jupiter is inhabited by massive cephalopods. Another, more intelligent race of cephalopods inhabits the moon Amalthea.
• The Space Odyssey Series, specifically the second entry (2010: Odyssey 2), describes a number of life forms in the atmosphere of Jupiter.
• In the works of Clark Ashton Smith:
  • "The Immortals of Mercury": The titular insufferable "Oumnis" Space Elves live in vast underground colonies to avoid the deadly sun. The surface is inhabited by savage, tribal Lizard Folk. Neither group wants anything to do with humans: the Oumnis prefer to hide their existence from humans; the reptilians, to sacrifice them.
  • In the Hyperborean Cycle of short stories, Saturn is known as Cykranosh and is the home of at least one Eldritch Abomination. It's habitable to human visitors in "The Door to Saturn", with an ashy surface, liquid metal lakes, and highly diverse inhabitants; the visitors end up living with a race of friendly, toad-like aliens.
• Alexander Jablokov's novel Deepdrive posits a future where our solar system gets heavily colonized by multiple races of Starfish Aliens.

Toys

• Star Trek of all things. The Mego toyline had a race of Fish People Neptunians.

Moons and Other Bodies

Comic Books

• The DCU:
  • All-Star Squadron: The Spectre was sent via hyperspace to the Pluto of another universe, where he discovered the two native groups (one evolved for the surface and one evolved to live under the ice) are locked in a generations long war.
  • Challengers of the Unknown: The challengers once rounded up three giant plutonian animals wreaking havoc on earth and then handed them over to intelligent aliens from Pluto who safely removed the creatures.
  • Legion of Super-Heroes: The founding member Imra Ardeen, a.k.a. "Saturn Girl", is from Saturn's moon Titan, where the local people all have some degree of telepathy. However, more modern continuities tend to have them descended from Earth colonists rather than being aliens.
• A group of The Eternals, of whom Thanos is a member, populate a colony on Saturn's moon of Titan. They're descendants of proto-mankind created and modified by the Celestials who were eventually moved to Titan, where they live to this day.

Literature

• In the Cthulhu Mythos, the Mi-Go are a race of winged, fungal Mad Scientists inhabiting Yuggoth, a dark planet at the edge of the solar system that's implied to be Pluto. H. P. Lovecraft's initial writings on Yuggoth actually predate the discovery of Pluto;^note (Though a trans-Neptunian "Planet X" had been hypothesized for decades at the time) the novella that prominently features the Mi-Go was written immediately after the discovery.
• The Space Odyssey Series: Europa turns out to have a complex ecosystem, including a number of intelligent species. The Monoliths convert Jupiter into a mini-sun in order to boost their development (and prevent their eventual extinction as Europa recedes from Jupiter and freezes solid), as their creators, the Firstborn, believe that their potential deserves to be explored. (Jupiter itself was also home to life, but all its organisms were simple creatures driven by instinct; the Firstborn decided it was worth sacrificing them for the Europans' sake.)
• The Callistan Menace has a Callisto inhabited by gigantic alien slugs. Like Europa, Callisto is considered one of the top candidates for alien life in our solar system in real life.

Webcomics

• In The Inexplicable Adventures of Bob!, quite a few dwarf planets and other bodies in our solar system are inhabited, but it's implied they're mostly colonies and it's possible none of these aliens actually evolved here. Well, except the dragons, but they're from Earth.

Western Animation

• Rick and Morty: In "Something Ricked This Way Comes", Jerry's insistence that Pluto is still a planet makes him a representative of its inhabitants, the Plutonians, in order to prove it is. It turns out that Pluto used to be bigger but is being mined dry, and Jerry is forced to swallow his pride about its status to prevent the corporations mining it to nothing and killing the Plutonians.

Real Life

• Jupiter's moons Europa and Ganymede are considered a good possibility for life, maybe even more so than Mars. While the surface is a frozen sheet of ice due to its distance from the Sun, because of the tidal forces exerted on its interior by Jupiter (which in a more extreme example have turned the closer moon of Io into a volcanic moon) these moons are thought to have a massive ocean underneath the ice; and the sheet of ice would protect the ocean from any radiation from Jupiter. If there is life, it's thought to have evolved similar to life in the deepest parts of the ocean.
• Saturn's moon Enceladus is considered a possibility for life for all the same reasons as Europa. Two things Enceladus has going for it that Europa currently doesn't is that Enceladus's ice sheet is shifting relative to the moon's interior, confirming that the subsurface ocean is global, and measurements taken by having the Cassini satellite travel through one of Enceladus's famous cryo-geysers showed that the water is salty and contains organic compounds.

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