Sol system (The Expanse)

The Sol system, known in our time as the solar system, is the center of human space in The Expanse scenario and was the origin of the human species. The Sol system is still the center of art and science. 
== Sol ==
Sol (The Sun) is the central star of the Sol system, named after the Latin word for sun and the Roman god with the same name. The star, obviously has no one living in or on it, as it is far too hot. Sol however is surrounded by several massive solar panels, which provide a massive amount of energy for the inner planets, the energy is collected from Sol by these solar panels and than sent by a laser towards a station, named a beaming station, this space station than shoots the laser toward any of the planets. Each of these solar panels is nearly 3 km tall and just 3 cm thick. While the beaming stations are on average about 60 meters tall and 35 meters wide. These laser stations and solar panels are almost all in possession of several megacorporations that sell this energy to planets, moons, asteroids, space stations and other outposts for money. The 3 main corporations in this industry are Nicoll incorporated, Schrodinger incorporated and Maiman industries. Sol is also surrounded by a Dyson swarm that houses the vast majority of humans in the Sol system, around 1.1 trillion people. The Swarm also has several huge computers, like the Berners-Lee and Shanon’s computer. The Swarm is made up of millions of O’Neill cylinders and ~1000 McKendree Cylinders, the oldest of which is Niven Station.
== Mercury ==
Mercury is the first planet from Sol with a day-night cycle of 176 days. With a scorching hot (427°C) day and freezing cold (-173°C) night side. Mercury is mostly used as a mining base. Mining vehicles move around over the surface and since Mercury rotates so slowly, it is relatively easy for the vehicles to stay in the twilight zone. So the vehicles move to a spot, mine for time (normally several Terran days) and when it becomes too hot or too cold, they simply move on and repeat. These mining vehicles travel in groups, with 3 types of vehicles: the containers, which store the ores and minerals, the miners, which mine the ores and the controler, which decides when to move on and when to stop. When a container is full, it usually leaves the group and goes to the nearest mobile factory where the materials are left, the factory then turns the materials into usable objects that can be sold, a truck leaves the factory and goes towards one of the launch loops. These products are then put inside a ship which is launched from the launch loop . There are also permanent immobile bases, nicknamed mushroom habitats because of their shape. These habitats stand upon pillars made from barely conducting material in order to not get any heat from the ground, with a huge mirror above the base, this mirror can be moved around to block the sunlight, it also doesn’t need any high tech engineering since the gravity on Mercury is only 38% that of earth and there is no airpressure or wind. During the day the habitat is powered by a fusion reactor and uses solar panels in order to load a battery for during the night. One of these habitats can support around the 5000 to 15000 people. The total permanent population of Mercury is around the 132 million with an additional 32 million temporary inhabitants are on the planet at any given moment. 
Mercury has some major advantages and disadvantages for spacecraft. The major advantages are its low gravity, making it easy to escape the planet and its almost non existent atmosphere, again making it easier to leave. This atmosphere is also the major disadvantage, since there is no atmosphere ships can’t use the air to slow down and have to use fuel. Mercury is controlled by the Mercury republic, this government imposes rules on mining and controls the people that live on the planet, its capital is Maia, named after the mother of Mercury. The planet remains neutral in almost every conflict since the third Sol system war. Though many of the mushroom habitats pretty much govern themselves.
== Venus ==
Venus is the second planet from Sol and the hottest. With a synodic day (day-night cycle) of 584 days. The extremely dense atmosphere causes the pressure on the surface to be similar to being 900 meter underwater on earth and the average surface temperatur is 467°C. Luckily between 50 and 55 km from the surface the pressure and temperature are similar to that of earth. Most colonies are domed cities that basically hang on massive blimps, which keep themselves hovering with helium, most of which comes from fusion reactors, which have helium-4 as a waste produc (alongside 2 hydrogen atoms). The oldest of all the colonies is known as Niobe, named after the Greek character Niobe, the daughter of Tantalus. The major export of Venus is nitrogen along with carbon, both can be found in the atmosphere, nitrogen from Venus was used in the terraforming of Mars and in almost every orbital habitat. These orbital habitats usually float in the twilight zone of the planet, most of them are conected to a massive floating ring with a hyperloop inside, which is used to transport people and resources between the floating habitats. Venus is not controlled by any government, most of the floating habitats rule themselves and have different ideals, but never go to war since that would risk all Venusian colonies as they could collapse and fall in the atmosphere, Terra and Mars both control several of these habitats, but never really fight. The most powerfull government on Venus is the Venusian confederacy, which control about a third of the habitats on Venus.
== The Terran system ==
=== Terra ===
see Terra (The Expanse)
=== Luna ===
Luna, coming from the Latin word for moon, is the moon of Terra and the location of the first base in space. Luna has a series of launch loops these are only 80.5 km long. These accelerate a craft at 4G, so that the craft leaves and enters orbit in just minutes . Lagrange point Terra-Luna 1 is home to Borman station, an O'neill cylinder with 5 million inhabitants and one of the most important stations in the Terra-Luna system. Lagrange point Terra-Luna 3 is home to Gagarin station with a population of 4.3 million.
A series of large liquid mirror telescopes made from ionic salts are located on the dark side of the moon, sometimes nearly 3 km across. The dark side of the Luna was, before humanity began to spread to other planets, home to several radio telescopes because they were blocked from the chatter of Terra. Luna has a population of 1.2 billion people, mostly in cities under domes that have been covered with dust. If a ship tries to get into a city, it must land on a landing platform outside, then the materials or people go through a tunnel (that is conected to their ship like the PBD of airplanes) into the city. Most of these cities are powered by solar and fusion energy. 
On the dark side of Luna, humans constructed the massive Armstrong laser array, the reason for this is to shoot asteroids before they can hit Terra (or any other inhabited location), while at the same time making it impossible to hit any city on Terra with this weapon. The major export from the moon is ice, but oxygen, silicon, iron, calcium, aluminum and magnesium are also major exports, being mined from the crust of the moon. 
Luna is controlled by the Lunar protectorate, it is technically under control of Terra, but is basically independent, most of the habitats have some level of autonomy over the protectorate. Luna sides with Terra in almost all conflicts and when it doesn’t, it usually stays neutral.
== The Martian system ==
=== Mars ===
Mars, also known as the red planet, is the third planet from Sol. Colonization of Mars started with the construction of 3 small settlements, after several decades a space elevator named Mariner (named after the Mariner probes) was constructed. After this 17,000 km space elevator was finished many more ships were launched towards Mars, mostly from Borman station, Gagarin station and Luna. The space elevator‘s base is near Pavonis mons in the colony typically just called Pavonis. The Stanford torus at the top of the elevator is called Port Tharsis. Most original colonies were inside lava tubes with only some domes on the surface which act as hydroponics. 
The terraforming of Mars was an 800 years long process which started in 2370 and ended in 3170. Most of the hydrogen for water and the atmosphere came from ice in the outer system and Luna, most of the nitrogen and methane came from Titan and Venus, while the oxygen came from basically every planet in the sol system. The first step was building thousands of massive orbital magnets, these magnets created a magnetic field, after this the gasses and water were brought in and massive orbital mirrors, only a few millimeters thick but hundreds of kilometers wide, heated the poles letting out water, this process continued and when finally bacteria, mosses and eventually even plants were introduced the oxygen level rose. During this 800 year long time a lot of domes were reinforced to protect against the chaos on the planet. After 800 years of this constant construction Mars finally became habitable, though The ground is still reddish and the oceans aren‘t too deep.
So Mars got its magnetic field from massive orbital magnets, the atmosphere (nitrogen, methane) came from Venus, Titan and plants that were places after that created oxygen, massive orbital mirrors reflected light on the surface making it warmer and melting the icecaps more water was brought from the asteroid belt and moons of the gas giant and Terra. All of this gave the planet the nickname Frankenstein’s Planet. Currently Mars has a population of 18 billion with the original Pavonis colony now being its capital. Mars is controlled by the Martian republic, its government works similarly to that of the USA. There are constant tensions with Terra and 4 Sol system wars have been fought along with many other minor conflicts.
=== Phobos and Deimos ===
Phobos is home to the Phobos research facility, an O’neill cylinder that was put inside the moon and spins in order to get gravity. The facility is used as a military research facility, working on faster, more powerfull and overall better ships and weapons. Phobos and Deimos were put into a stable orbit in 2547 by using the gravitational tractor technique: a ship flies next to the asteroid for about 12 years and then changes its course, pulling the asteroid with it, this is how both Phobos and Deimos were put into stable orbits. Most of the experiments on Phobos are kept a secret, though it is public that they were working with even more advanced genetic engineering. 
Deimos was a battle station, the smaller moon was armed to the teeth with torpedo launchers, machine and rail guns and even several ships are on or in orbit around Deimos. They were placed there as a first line of defence against Terran aggression. Deimos however was destroyed during the Paranoia war (3002-3005). In this war Terra thought that Mars was planning to attack and as a ‘preemptive retaliatory strike’, Terra fired 15 torpedoes at Deimos and destroyed the moon, debris fell down on Mars and formed a thin temporary ring around the planet. This attack started the Paranoia war.
== The Sol asteroid belt ==
The Sol asteroid belt, more commonly known as The Sol Belt or just the Belt, is a collection of asteroids inbetween the planets Mars and Jupiter. Most asteroids in the belt are C-types, which contain a lot of water and phosphorus and are therefore incredibly valuable, most asteroid bases are on C-types (sometimes called Cs). Asteroid mining is a huge business, but there are so many competitors that no one owns a monopoly on the market at all. There are in fact many families which live solely on asteroid mining, often these families have 1 ship which they send to the nearest asteroid and remove all the materials, then go to the next asteroid and the next, until their ship is full and go to the nearest asteroid habitat and sell the goods. 
While they do make a lot of money on this, most of it has to be spend on taxes and the ship. When they mine an asteroid normally they first put a massive aluminium bag around it (with the bigger ones they place pressurized domes) and mine inside a breathable atmosphere. Most asteroid habitats are O’Neill cylinders inside asteroids, they hollow out an asteroid and than put this cylinder inside the hole, these are than spun up in order to generate artificial gravity, normally about 0.3 G. Small bases have several thousands or even millions of inhabitants but the biggest have way more. Most asteroids govern themselves or are part of a small group of asteroids that govern each other. 
=== The Major asteroid bases ===
==== Ceres ====
Ceres has been hollowed out and filled with 6 O’Neill cylinders, each of these has a population in the millions and their own harbor, the 6 cylinders are called: Occator, Kerwan, Yalode, Nawish, Rongo and Toharu, each are named after the crater they’re under, these craters are used as harbors. When a ship arrives it enters a zero-G chamber, the ship is connected to an elevator shaft, this elevator brings the cargo and crew to a hyperloop station that connects with every cylinder inside Ceres. Ceres has such a large population in fact that it is often seen as the capital of the belt. 
Ceres’ main employment is ,unsurprisingly, asteroid mining, but agriculture and tourism are also big industries alongside the harbors, though not nearly as big. The O’Neill cylinders are conected to each other by a network of hyperloops named the Proserpina Hyperloop Network (PHN) name after the daughter of of Ceres in Roman mythology and the Persephone Hyperloop Network (PeHN), named after the daughter of Demeter, the Greek version of Ceres. Ceres has a total population of 934 million and is expected to hit 1 billion by 3500.
==== Vesta ====
Vesta is the second largets asteroid in the Belt and was the third to be colonized. The asteroid has been hollowed out and filled with 5 O’Neill cylinders: Egeria, Forum, Atrium Vestae, Aedes Vestae, all named after objects that have an affiliation with the Vestal Virgins. Vesta has a population of approximately 647 million people. 
It is orbited by a series of discarded spy satellites which were built by Terra to spy on Mars. The asteroid is one of the most violent places in the asteroid belt, constantly changing its side in the Terran-Martian tensions, all of the Sol system wars saw at least one battle at Vesta, and the colony is almost constantly on the brink of civil war. This is because the asteroid‘s population sides for around 49% with Terra, 50% with Mars and around 1% of people that are neutral. The asteroid is also home to the largest amount of religious people relative to its population, around 43% about a tenth of which are extremists. The Vestal government has no real power and therefore the asteroid exists in a constant state of anarchy making it a perfect hiding spot for terrorist and criminal organizations. The asteroid has such a bad reputation that ships only dock for necessary supplies to the base, avoid going inside and avoid the base overall.
==== Pallas ====
Pallas is the second or third most important asteroid in the Belt depending on the source. With 4 O’Neill cylinders (Athena, Erechtheus, Praxithea, Chthonia) named after characters in Greek mythos that have some type of relationship with the goddess Pallas Athena (the main O’Neill cylinder Athena is also sometimes called Pallas Athena). Pallas uses a different type of harbor from the rest of the belt, only 17 other asteroids use the same method, the harbor is on a long spire which sticks out from the asteroid, the spire branches our into several more, a ship docks at one of these spires and the crew and cargo are brought with a hyperloop to the asteroid itself. 
Depictions of O’Neill cylinders will often have a smaller tube in the middle conected to the outside, the hyperloop flies through the spire until it is within the asteroid, where it slowly begins to spin, until it reaches the central tube and halts. The passangers get of the hyperloop and use elevators to get down. With a total population of 500 million people, Pallas is overcrowded and doesn’t have clean air. Ironically the asteroid which was named after the goddess of warfare (mostly tactics) is one of the most neutral bases in the Sol system.
==== Eros ====
Eros is really only considered to be important because it is so old, it was one of the first asteroids that was colonized. Being the fourth one after Ceres, Vesta and Sol-AA-16385. Eros is also often called The Trash Can of the Belt, this is mostly because after years Eros became less and less useful up untill it no longer had any use other than holding people, the crews of the ships that arrived began to pollute the station. It has gotten so bad that Kurzon Aguda, a physicist from Eros was once quoted as saying: “If there was any place in the universe unworthy of being named after the god of love, it is Eros.” 
Currently Eros has 6 small O’Neill cylinders: Anteros, Hedylogos, Hermafroditos, Hymenaios, Himeros and Pothos, all named after Greek erotes . Each house several million people, giving the asteroid a total population of 120 million. Though some of them have been so polluted they are officially uninhabitable and should be replaced (most notably Himeros). Eros’ ports work in the same way as Ceres’.
=== The Belt 20 ===
The Belt 20 is an alliance between the 20 richest and most powerful asteroid bases in the Belt. The members are: Ceres, Vesta, Pallas, Sol-AA-16385, Hygiea, Interamnia, Europa, Davida, Sylvia, Cybele, Euphrosyne, Juno, Herculina, Iris, Sol-GT-85682, Sol-JK-42, Doris, Psyche, Thisbe and Melpomene. These 20 governments meet at Apophis, an uninhabited asteroid that is only home to a single cylinder for these meetings. They make laws, sign treaties and cooperate to support each other and the Belt in the wider system-wide scale. Eros used to be a member when it was founded, but was kicked out.
== Jovian system ==
=== Jupiter ===
Jupiter’s main export is unsurprisingly gas, mostly helium-3 and deuterium for nuclear fusion. There are several ways in which this is extracted from the planet, one of which is having small ships (called Gannets) fly into the atmosphere, collect gas and left before they get too heavy and slow down then they are brought to a ship in orbit and the gasses are separated by type, this technique which is named the gannet technique, was mostly used during the early phases of Jovian colonization and is no longer a common occurrence. 
Currently an orbital ring hangs inside the atmosphere of Jupiter, high enough to be above the winds and low enough to protect against meteors. The ring has several giant tubes going deeper inside the atmosphere, sucking gas up, this gas is then brought of the ring by either ships or magnetic launchers, these use magnets to generate magnetic field and sling the gas, which is first charged, out into space. The ring also has turbines attached to it that generate energy from the constant winds, the same design is used in all other gas giants. There are even several magnetic gas launchers in the atmosphere, that aren’t connected to the ring and use their own tubes. The planet has no permanent population, but at any given moment there are about 13 to 16 million people on the planet.
=== Galilean moons ===
==== Io ====
Io is the mining colony of the Jovian system, the moon is surrounded by several space stations and even has a space elevator, though this one is no longer in use and is planned to be demolished in 3470 because of impact danger. No one actually lives on Io, some people visit for several weeks at most a month (even the longest time anyone has stayed there was just 35 Terran days). People normally go down with a ship to the surface, mine for a few days and then come back up, the major resources are silicate, sulphur, sulphur dioxide and iron. It is to the rest of Jovian system as what Mercury is to the inner Sol system. Io is also the only one of the Jovian moons that isn’t under control of the Jovian alliance or anyone else and follows the Universal Laws a set of laws created by Terra and Mars in the Treaty of Ceres.
==== Europa ====
Europa was the second of the Galilean moons to be colonized, simply for the fact that it could have life. Almost immediately submarines and small drones were send into the ocean and explored, after dozens of years with no life being discovered, most people believed it didn’t exist so a aquaforming project began, operation Rhadamanthys, named after one of the sons she had with Zeus. It started with lowering massive fusion reactors inside the ocean, these heated the water and gave of light for photosynthesis, large amounts of photosynthetic organisms were implanted and over time even a large amount of Terran sealife and genetically modified fish. Creating so called submarine archipelagos, these are places full of life around these fusion reactors which are kept at different depths, life also exists outside of these but is overall smaller and much rarer. Most people on Europa even live in small underwater cities near these reactors and just tap into the power grid. The total population of Europa is 235 million.
==== Ganymede ====
Ganymede was the last of the moons to be colonized and has therefore the smallest population: only 67 million. Most of the colonies on Ganymede are small underground cylinders, though it is home to several surface structures. Mostly massive factories which use the vast amount of resources all over the Jovian system to manufacture goods out of them which are then transported throughout the system, Ganymede also has many orbital drydocks and ports alongside the oldest still used space elevator in the outer Sol system. 
Ganymede has a salty ocean under its surface, just like Europa and Callisto, but unlike those places, the moon actually has life, this life was discovered by small submarine drones, but is quite different from ours, it is still carbon based and follows the laws of biology and evolution, but most creatures are still single celled organisms, with even the largest creature on the planet, still being only a few cells. The big difference however is that these organisms have bigger cells than ours, they are still microscopic but way larger than any bacteria on Terra, the largest on Terra is about 5 micrometers in length, while these are an astounding 13 micrometers in lenght, the largest organism is even 51 micrometers long, still too small to be visible with the naked eye however. 
This caused amazement in the scientific community and is still regarded as the single most important scientific discovery in history, even beyond agriculture, the wheel, the computer or space flight. It fundamentally changed many religions as it was now plausible that humans are not the only intelligent creature in the cosmos, therefore most religions either see them as a failed or future experiment from a god or gods, a result of panspermia, but from Terra not any other planet or even just straight up deny that these creatures actually exist. Ganymede is visited by countless people each year and has millions of scientists at any given time doing research. The overall colonization of the moon was halted and many people even want to abandon it completely as to leave the life undisturbed.
==== Callisto ====
Callisto was the first object in the Jovian system to be colonized, because Callisto is outside of the huge radiation belt around Jupiter. In order to get on or off the moon one needs to go into 1 of a series of orbital launch loops, which launch craft at extraordinary speeds away from the moon or slow them down. Down on the surface dozens of dome-shaped greenhouses dot the surface, it has the largest amount of farms in the outer solar system hence the nickname The Breadbasket of the Outer Sol System, all the space stations in the system produce about a hundred times of the amount of food that Callisto does, but nonetheless the moon produces almost as much Terra or Mars. 
Most of the light comes from the sun (which is actually still quite bright without orbital mirrors, even on Pluto) and Jupiter, which reflects the light in a reddish or orangish glow (since Callisto is tidally locked, Jupiter is a permanent feature in the sky) and of course artificial lighting. Most people live inside O’Neill cylinders that have been put inside the icy crust. Next to one of these cylinders is a massive hole dug under a dome straight through the crust al the way down into Lycaon, the underwater salty ocean named after the father of Callisto in Greek mythology, which is full of amonia, one of the major exports of the moon. was once a major places where people searched for extraterrestrial life, now it is just a tourist attraction. The total population of the moon is 1.1 billion.
=== Other moons and rings ===
Just like in the Belt, most of these small moons are just hollowed out and have an O’Neill cylinder inside, though there are several special cases. The rings around Jupiter are small and not really useful which is why they are almost exclusively used for mining ice. In all the years people have been mining this ring, already about 50-60% of the rings has been mined.
==== Carpo ====
One of the special smaller moons is Carpo, an asteroid which is home to the Carpo Research Base (CRB) a small research base which was created to make genetically modified viruses and bacteria These did cause several system wide pandemics, including the Callisto flu which ravaged the system in 2606-2607 and killed nearly 103 million people, or the Carpo plague (death toll: 98 million) and the Blue Death (death toll: 41.5 million) the last pandemic from the station started in 3221 and ended in 3251 killing 5.1 million people, while not as deadly as the other diseases (only having a 1 in 1 million mortality rate) it was extremely contagious infecting around 2 trillion people, a massive portion of the population and is still infecting people to this day though we have a cure by now. It also was one of only 3 pandemics to ever go interstellar, infecting people in not only the Sol but also in the Alpha centauri system. This pandemic was such a disaster it not only stopped 2 civil wars (on Mercury and in Ceres) but also the 4th Sol system war. After this outbreak the station was abandoned and launched into Jupiter. The reason that hadn’t been done already was that all the previous ones couldn’t actually be traced back to Carpo at the time and were just guesses by conspiracy theorists.
== Saturnian system ==
=== Saturn ===
Saturn was colonized in the same way as Jupiter with it only being a resource extraction facility, though an orbital ring was never constructed. The planet’s hidrogen was and still is a major export and the main export of the Saturnian system.
=== Moons and rings ===
The rings of Saturn are the most visited tourist attraction in all of human space and bring in a lot of money for the inhabitants of the Saturnian system. While originally the rings were mined for ice after a while people decided that they were to beautiful to be mined for a material of which the belt, Jovian, Caelean or Neptunian system along with the Kuiper belt and Oort cloud and even the rest of the Saturnian system already had enough.
==== Rhea ====
Rhea is the second largest moon in the Saturnian system and the major population center, it is home to 349 million people. Most people live in subsurface cylinders or in rings build on top of a pillar on the surface. The moon is home to Rhea Base, the capital of the United States of Saturn. The moon’s major export is water ice which is transported throughout the sol system. The construction of a space elevator was started in 3453 and will be finished by 3465. Currently, taking of is mostly done through one of the many launch loops. The moon was originally a protectorate of Mars but later gained independence during the Saturn Rebellion.
==== Enceladus ====
Enceladus was often seen as the Europa of the Saturnian system and its use reflects that. After no life was discovered in the subsurface ocean of Enceladus, a massive operation similar to the one on Europa started. Since the ocean is less deep than the one on Europa and also way smaller, the operation went faster and the ocean is currently home to thousands of subsurface fusion reactors heating the water which is filled with fish from Terran oceans, alongside engineered animals. Most of the people on the moon live in cylinders on the surface, the population of Enceladus is 306 million, the second largest in the Saturnian system. The major export is waterice and water from the plumes. While the majority of people live on the surface, a decent amount live in under cities like Okeanos, the capital of Enceladus, one of the 60 states.
==== Titan ====
Titan is the largest moon of saturn and the 2nd largest in the Sol system. Most people see Titan as a place we want to send a lot of people to, however Titan is one of the least populous moons around Saturn, as no one actually lives on the surface, but in orbit around it in stations like Eos, a stanford torus with 2 million inhabitants and many more. The surface of Titan is almost completely abandoned with the only way of easily seeing that man lives here, is the orbital ring, Kronos (named after the king of the titans and the titan of time) along with the space elevators going up to this ring. 
Since the moon is so cold it is the perfect place for automated industry, countless factories underground or under the methane lakes along with several ones that float inside the atmosphere similar to the ones on Venus. Countless corporations have set up factories here: Helping Hand Inc., Hangeer, Takomat, Icerion and many more. But the single most special thing on the whole moon is Metis, named after the Greek titaness of wisdom. Metis is the single largest supercomputer in the Sol system, or anywhere for that matter, the computer has a processing power of 4.2 septillion calculations per second. More than enough to simulate human consciousness and it was the first machine to actually achieve self awareness. This had a similar blow on how humanity viewed itself as the discovery of alien life on Ganymede. The machine is just a huge database but also controls the moon itself and over time it gained the nickname The Titan.
== Caelean system ==
=== Caelus ===
After the colonization of the Uranian system, the colonists opted for a name change and after about 20 years the name of the planet Uranus was changed from the Greek god of the sky to the name of the Roman god of the sky, Caelus. Caelus has relatively slow winds when compared to other gas giants and the gravity is not that much stronger than Terran gravity, therefore it was the perfect place for settlements and it is in fact the only gas giant in the Sol system that has people living permanent lives in its atmosphere. The total population is around 607 million, making it the capital of the OSA, the Outer System Alliance, an alliance between the Caelean and Neptunian system together with several dwarf planets and comets inside the Kuiper belt. 
Most of these people live in The Hanging Cities, which are huge constructs that hang from the orbital ring, Ouranos, into the atmosphere. They are famous tourist attractions and one of them, Acmon, is the OSA capital.
=== Moons and rings ===
The rings are used as ice mining colonies, though some of them are habitats similar to the ones in the Belt.
==== Oberon ====
Oberon is the most famous Caelean moon and is home to a population of 612 million people, the largest in the Caelean system. The moon is mostly home to cylinders but also several tori standing on pillars. The moon is home to a series of large orbital drydocks and launch platforms which were the location the first ship to Ross 128 was launched from. The moon also has a shallow subsurface ocean and plans to undergo a similar operation to the ones on Europa or Enceladus have been made but will at best only start around the 3500s, if they will start at all.
== Neptunian system ==
=== Neptune ===
Neptune is surrounded by a massive orbital ring, this ring is is eliptical in contrast to the circular rings around Terra and most other rings. This ring is often nicknamed Neptune’s Chainsaw, though its official name is Oceanus. Massive tethers hang down from Neptune’s Chainsaw and suck up gas from the atmosphere, this gas is traded throughout the Sol system and powers the majority of colonies, stations and vessels inside the Neptunian system. Neptune’s Chainsaw is also home to thousands of hanging cities, these cities hang towards Neptune and each house at least a million people. 
Besides that there are also giant hangars that house and repair ships. Still the main use of Neptune’s Chainsaw remains the collection of helium-3 and hidrogen for fusion, these gases are then loaded into spherical containers and sold. Ships can also come and refuel.
=== Moons and rings ===
The rings of Neptune are a massive ice mining location and the location of several space stations.
==== Triton ====
Triton is the biggest moon of Neptune and is often thought to be a captured dwarf planet, it is the capital of the Neptunian system and one of the most important locations in the OSA. The moon’s surface is dotted in with small research outposts and mining locations along with harbors and a space elevator. The moon is also home to countless subsurface cylinders, spinning to generate gravity. 
Triton has a population of 430 million, a massive population for an object this far out. The capital of the moon is not actually on Triton, but in a low orbit above it, namely Thalassa station, named after another Greek sea god. The SS Salacia was the second ship to colonize the Neptunian system, it was later turned into a museam on Triton.
== Kuiper belt ==
=== Kuiper belt ===
The Kuiper belt is a massive belt of comets that is 30 to 50 AU away from Sol, a trip that longwould take an interplanetary ship on average 28 and a half days to complete. The Kuiper belt is often seen as a larger version of the asteroid belt though it has some disadvantages compared to the Belt, mainly the fact that it has far fewer minerals, most metals and silicates are rare to find in the Kuiper belt. It is also a lot further away from the inner sol system, though with current day engines that is not really a problem. However the Belt lacks the massive amounts of ice that the Kuiper belt is filled with, countless mining corporations like Corporation M and Yellow Dragon all have mining operations in the Kuiper belt, to mine for ice, which is extremely useful; not only can ice obviously be melted for water, but it can also be split producing oxygen and hydrogen. A lot comets in the Kuiper belt are home to mining operations, though some of the bigger ones are also home to cylinders.
=== Plutonian system ===
==== Pluto ====
Pluto is a dwarf planet that together with Charon forms the Plutonian Republic. The planet is home to several subsurface cylinders that house millions of people. It is also home the Elysium, a posthumanist colony. The planet is a province of the Plutonian republic. Its capital is Tartarus, a giant pit that was made inside Pluto with many rotating tori and cylinders inside of it. Tartarus is also the second (or second to last) stop on the Acheron. The Acheron is a gigantic space elevator that goes from the Tantalus lake, a subterranean lake with several underwater trading hubs, to Tartarus. After that the Acheron travels up to Taenarum, a rotating habitat located at the barycenter of Pluto and Charon and the capital of the Plutonian Republic. After that it travels all the way to Charon.
==== Charon ====
Charon is by far the largest moon of Pluto, being so large it is seen as a binary planet more than a moon. Pluto and Charon are also tidally locked, so that they always show the same face to each other. The Acheron arrives at Charon on Sisyphus’ Mountain, a colony located on one of the few mountains on the moon. Charon is also home to the Charon Military Base, a Martian outpost that is the headquarters of the Martian 8th and 9th fleet. Terra also wanted to construct a military base on the surface, but Charon refused, fearing a battle in orbit around the moon or even on the moons surface, which would be a disaster. The inhabitants of Charon insisted that the capital of the Plutonian Republic be placed at the barycenter of both planets.
==== Styx ====
Styx is the second moon of Pluto and way smaller than Charon, which has a radius of 606 km. Styx only has a length of 16 km on the longest side. It is the only moon in the Plutonian system that is completely abandoned, it was originally home to an outpost of about 100,000 people, but this one was later abandoned. The surface is also home to a communications disk which was abandoned in 2803.
==== Nix ====
Nix is the third moon of Pluto, named after the greek primordial deity of the night. The moon is home to Erebus (named after the primordial deity of the darkness and husband of Nyx in Greek mythology), a cylinder which houses a population of just 8 million people. The moon has very few resources that are truly worth anything and therefore the majority of people on the moon work on either Pluto or one of the other moons. The moon is also home to a radiotelescope and a small Martian corvette that crashed on the surface of the moon in 2896.
==== Kerberos ====
Kerberos is the fourth moon of Pluto. Kerberos is home to a research outpost which experiments with radiation, lasers and plasma. While the outpost was originally only for science it later also began experimenting with weapons and created several powerfull dirty bombs. The moon also has a small torus on its surface which houses around 70,000 people. Both Mars and Terra have fought battles over the research base on the moon, but it is currently, just like the rest of the Plutonian system, under control of the OSA.
==== Hydra ====
Hydra is the fifth and final moon of Pluto. The moon was a mining base, as tens or even hundreds of thousands of people mined the moons surface for ice and transport it throughout the entire Sol system. Hydra was eventually bought by Terra. The Terrans later placed a military base on it, staffed it with 12,000 people and armed it with railguns and torpedo launchers along with several cruiser, which were placed inside secret hangers on the moon’s surface. During the fourth Sol system war, Terra attacked the base on Charon and as a retaliation Mars sent a fleet of warships which destroyed the Terran outpost and vaporized the moon.
=== Dwarf planets ===
==== Haumea ====
Haumea is a dwarf planet in the Kuiper belt that was discovered in 2004 , 1459 years ago. The dwarf planet has the shape of a ellipsoid. The planet is home to a population of 10 million people. Most of these work in the ice mining industry and live inside subsurface cylinders, that rotates in order to generate 0.5 G. Haumea is one of the only object in the Kuiper belt, together with Eris, a couple of comets, some Terran and Martian bases, that is not a part of the OSA. Haumea is independent from the OSA and unlike Eris, it is not planning on joining it any time soon. This is mostly because of a terrorist attack, before the OSA was reconized it was seen as a terrorist group and acted as one. 
False information from one of their sourced said that Haumea was home to a secret military base from either Terra or Mars, the OSA sent some people who blew up in one of the cylinders under the surface, killing 768 people. Both Mars and Terra have good relationships with Haumea because it isn’t a member of the OSA, and the negotiations between Terra and Mars at the end of the 3rd and 4th Sol system wars took place here. The two moons of Haumea (Hiʻiaka and Namaka) both house less than a million people and are primarily used as ice mining facilities.
==== Makemake ====
Makemake is a dwarf planet in the Kuiper belt which was discoverd shortly after easter 2005 and was given the name of the creator and fertility diety in the myths of the Rapa Nui, the native people of Easter Island. The dwarf planet is often ignored by the rest of the Sol system for the fact that it has a small population, no military power and no tactical value. It is covered in methane, ethane and nitrogen ice, these are also its main exports. The nitrogen ice is mostly for space stations and the methane and ethane are both used for several other purposes, such as anti-freeze. 
The dwarf planet has a population of just 4 million, less than half of the population of New York City in the early 21st century. All of these live in one of 2 cylinders: Uoke and Hotu Matu’a. The only use the dwarf planet has on the large Sol system scale, is its weapon production facility, which isn’t even that big. Makemake has 1 moon which is the location of a massive liquid mirror telescope.
==== Eris ====
Eris is the most massive dwarf planet. It is named after the Greek goddess of strife and discord, which does fit with its population. Eris is still independent from the OSA, but unlike Makemake, the majority of the population (about 90%) do want to join the OSA, but the richest 10% don’t. This makes the dwarf planet rather unstable. The moon‘s population of 9 million lives inside 2 cylinders: Harmonia and Concordia, which are conected with each other by the Discordia Hyperloop Network. The major export from the dwarf planet is methane ice. Eris has a small navy stationed in orbit around itself, in order to protect the dwarf planet’s independence, but overall the 90% are beginning to win and most experts believe Eris will join the OSA by the year 3480.
== Oort cloud ==
The Oort cloud is a massive cloud of comets surrounding Sol, it was named after the Dutch astronomer Jan Oort , the massive cloud is 50,000 to 200,000 AU (0.8 to 3.2 ly) from Sol, a massive distance that would take an interplanetary vessel decades to complete, an interstellar ship would take around 8 to 32 years to make this journey, but since the distance is so vast interplanetary vessels are never used. The Oort cloud is also almost completely abandoned, there are only 2 habitats in the Oort cloud: Epimetheus station and Polyphemus station, making a total population of the largest area in the Sol system just 4 million. 
This is mostly because the Oort cloud isn’t really needed, it is far away and has no resources that can’t be found anywhere closer to Sol, it is thought that only 0.1% of all comets in this area have been discovered and the possibility of a Planet X still exists, though it isn’t likely. A plan has been proposed called Project Sealion which will go to the Oort cloud and tap the vast resources of water there, the plan would rely on so called Sealion-class colony ships which would transport O’Neill cylinders and Stanford tori to the cloud, the operation would start anywhere between 3500 to 4000. Until then this place remains uncontrolled and unclaimed with only small exploration vessels traveling through it.
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