Spacer Worlds

The Spacer Worlds, also called the Outer Worlds and the Forbidden Worlds are the 50 planets colonized by humans in the earliest stage of the galactic history: so called "First Wave of Colonization".
Their inhabitants were called the Spacers. The first extrasolar worlds of humanity, the Spacer Worlds were colonized in the Age of Aquarius, during the revolutionary period of 2160 - 2900. In those times they were called the Outer Worlds, opposed to Earth and the inner colonies in the Solar System (like Mars). 
The first colonized Outer World, arguably the largest and most beautiful, was physically discovered in 2160 (in the early 21st century the Kepler Mission proved its existence) during the first planned hyperspatial travel and named New Earth . As that world was relatively close to Earth, the terraforming and initial settlement were quite easy despite of travels lasting for months. The Colonists were strictly selected to be the bravest, strongest and most intelligent. Later the rich ones also joined the settlement, thus together creating the beginnings of a new race. Very powerful corporations saw the huge benefits in the new world's creation. Influenced by the dominant ideas of the individuality, freedom, idealism and perfection, the Colonists started to develop the world utopia. That's why they quickly (in 2200) changed the name of their new world to Aurora. That name symbolized the dawn of a new, beautiful space age. Aurora name was smoothly accepted and was strictly associated with the "First World" till its downfall. There wasn't a place for the "New Earth" in the hearts of colonists anymore...Furthermore they wanted to erase all the mistakes and flaws of the Earth's civilization, in fact rejecting their heritage. They had a comforteble situation because of the positronic robots' creation in the 21st century. Robots were perfect for the terraforming and buliding purposes, making the New World's settlement ver quickly and harmless. Those machines was turned into the loyal slaves which were making all work for the pleasure and luxury-seeking Aurorans. As Aurora was the fully successful experiment, the colonization of the nearby suitable worlds began around 2300. People from Earth who wanted to be free from life on Earth, who wanted a new better, utopian life, were departing Earth in masses. However the limitantions existed due to the spaceships' capacity and the Colonists' desire to keep their planets empty, in opposition to the crowded Earth which population was growing rapidly from 12 billion to over 20 billion. During years 2300-2600 the 30 Outer Worlds (including Aurora) were colonized. Then Earth government ordered the closure of further colonization, because of the technical and financial limitations. In that situation, the Colonists, increasingly called the "Spacers" (because they were travelling in space) colonized to 2700 the (still nearby) 19 worlds, ending colonization at the most distant, 49-th Outer World - Hesperus, named in opposition to Aurora (the evening vs. the dawn). Hesperus symbolized the end of the space colonization era and the beginning of the complex settlement and world-buliding.
All 49 Outer Worlds were so important not only beacuse of their emptiness, abundant resources etc. They were disease-free. There were no viruses or bacteria. Seeing the extraordinary chance to build the utopia the Spacers introduced the high developed medical technology, careful breeding, selection of plants and animals to keep their planets clean, to enlarge their personal lifespans and to ensure personal youth and health. The different environments of the colonized Worlds caused the intense biological mutantions which only accelerated the genetic change of the colonial people. Within first centuries of space colonization the Spacers clearly opened the process of becoming a new human race, or races - as the populations of 49 distinct worlds were fairly hermetic and homogenous in nature. 
The Spacers' idea of uniformity and perfection was strongly opposed to the Earth's government views. Early, Earth was supporting the colonization with very high amounts of money and technology (it was a part of the corporations' plans as well) because in the future Earth wanted to use the colonial worlds for own benefits like importing food, luxury goods etc. Meanwhile the Spacers desired to create their paradises only for their own, without sharing. They were viewing themselves as the superior, near-perfect humanity's branch. They used countless robots to quickly gain benefits from their worlds and turned them into the weapon against Earth. 
Thanks to robots' labor and richness, to 2900 the Outer Worlds very quickly became more powerful that the mother world of Earth. They were thinly-populated (average population of 400 million people), Aurora was the most populous world with 750 million inhabitants. Immigrantion of the incoming Earth's citizens was closed in 2850 by the now-sovereign Spacer communities, due to protection of the clean environments, genetic purity and the luxuries of the Outer Worlds, which simply turned them into the prohibited, elitist zone. The growing population process was inhibited because the Spacers introduced strict population control and the foreign immigration from Earth was stopped. Thus the Outer Worlds' population remained at level of 20 billion people for 49 planets. In the same time Earth boasted 30 billion people who were striving for the resources and food. The Spacers viewed Earthmen as the degenerated, pathetic race of sub-humans (nearly animals) and were willing to show the upper hand. 
In 2900 the close and violent confrontation between Earth and the Outer Worlds finally happened, known as the "Three-Weeks War". Earth ordered her colonies to be loyal and open their space again for the Terran immigration. The Spacers replied with the interplanetary conference on Hesperus. Aurora wanted to defeat Earth and unite the other Outer Worlds under her hegemony, but the two important planets Rhea and Tethys were in opposition, didn't recognize the Auroran leadership. The Spacers were on the edge of an argument, while Earth sent a threatening message to all Outer Worlds, uniting them finally in the common hatred. Aurora attacked then the Solar System, encouraging the rest of the Worlds to do the same. Earth swiftly lost all battles in her own system and was besieged by the Spacer fleet. Ultimately the Spacer plan to destroy Earth failed, but they won the War and bacame dominant over their defeated mother world. The Outer Worlds decided to turn Earth into the prison for her own people and keep Earthmen away from the outer space. As the inner Solar System colonies were devastated by the Spacer forces Earth was left without any outer resources and even travel within the system was risky. 
So, Earth during 2000 years after the War became heavily overpopulated (population stabilized at 80 billion) and the global population was forced to live in the vast underground steel cities, kilometers long, wide and high, to keep the surface for farming. Earth culture degenerated into the communist-like nightmare. 
However in the same time on the (already officially called) Spacer Worlds the civilization was thriving in the full splendor and glamour. The Spacers achieved their goals: pefrect, clean and effective environments, lifespans reaching to 300-400 years in youth and beauty, quadrillions of robots as servants and bodyguards and the unlimited richness. Every Spacer had 20-30 personal robots, own mansion with the estate and didn't have to work hardly. Life was pleasant, and the libertarian attitudes of the Spacers made them overly hedonistic. The complete security provided by the robots eradicated the smallest traces of crime, made the privacy and freedom the holiest things and turned the Spacers into decadent and quite pacifist people, who despised any violence. The feelings of superiority towards Earth remained with their all strenght but the Spacers didn't want to destroy Earth any longer. Earth was always depicted as the barbarian place full of inhumane emotions, behaviors and corrupted nature which was making the Spacer amused and comfortable to have a comparison between his/her life and a life of the Earthman. The Spacers were very proud that they could live in the paradise while the sub-humans from Earth suffered miserable conditions because of their own mistakes. 
Due to the increased lifespans and common peace the Spacer population experienced the smooth and controlled growth: from 20 billion to 55 billion. Aurora's population was stabilized at 2 billion - the perfect number for the Aurorans, making Aurora still the most populous Spacer World. The ordinary Spacer World had around 1 billion people when those more important 1.2 - 1.8 billion (like Rhea, Tethys and Melpomenia). The Spacer Worlds banded together in the common Spacer Federation with the capital on Melpomenia (chosen as the neutral place), while Aurora remained the strongest and most advanced Spacer World - de facto leader of the rest of Spacer planets. The Spacer Federation wasn't a unitary political alliance, because of the mutual rivalry between individual worlds and Aurora's desire to maintain her hegemony. Ultimately every sign of warlike tendencies ceased to exist and Aurora created the system of her hegemony which guaranteed independence and peace for the every Spacer World, but made them subordinate to her. Only six worlds similar in power to Aurora could undermine her decisions to some limited extent, while the rest of the Spacer Worlds became bland and passive. During 2000 years of peace the Spacers developed and were enjoying their technological achievements, personal luxuries, pleasures and the amazing experience of the extremely long life. The Spacer culture was predominantly individualistic, the single person was in the center of attention and was the most important in the system. The family relation ceased to exist, the marriage institution was fragmentary, limited to the reproduction. The majority of Spacers were living without obligations, willing to do what they wanted, of course within the limits of common sense, when the robots where still careful to protect everyone. Because of the relatively higher populations than during the settlement era, the resources weren't equal for every Spacer and the system of salaries, jobs etc. remained, but in the deformed form. Ordinary Spacers were living like the aristocracy on Earth and the aristocracy of Spacers were living like the kings on Earth.
[Situation from the settlement of Solaria - IN PROGRESS] 
Based heavily on the Asimov's Robot Series.