In the Universal Century timeline, space colonies are giant artificial structures in space, designed to house large-scale human habitation. The Earth Federation was responsible for the construction of all the inhabited space colonies within the Earth Sphere, and around 10 billion people were space colony residents by the outbreak of the One Year War.
Nearly all colonies in the Universal Century (except some rare older colonies such as Moon Moon) are O'Neill "Island 3" type cylindrical colonies. Most of these colony cylinders are the "open type" with three giant mirror panels that reflect sunlight into the colony via transparent "window" walls, while the colonies at Side 3 are "closed type" cylinders without any windows. Every colony also has its own satellite modules for food production, energy generation and industrial operations.
Space colonies are placed at the five gravitationally stable regions in the Earth-Moon system, known as Lagrangian points. In most cases, each Lagrangian point can accommodate a significant number of space colonies, and the closely clustered group of neighboring colonies are known collectively as a "Side". It is possible to have two Sides occupying the same Lagrangian point in a binary system-like orbit to one another, as in the case of Lagrangian points 4 and 5.
- Lagrangian Point 1 (L1) is located between the Earth and the Moon directly over the latter's near side, and is one of the two nearest Lagrangian points to the Moon. It is the home of Side 4.
- Lagrangian Point 2 (L2) is located directly to the far side of the Moon. It is the other one of the two nearest Lagrangian points to the Moon and the farthest one from the Earth. It is the home of Side 3.
- Lagrangian Point 3 (L3) is located to the side of the Earth away from the Moon, just slightly outside of the Moon's orbit. It is the home of Side 7 and the migrated asteroid Luna II.
- Lagrangian Point 4 (L4) and 5 (L5) roughly share the Moon's orbit, located symmetrically ahead and behind it at a 60° angle from Earth's center of mass. They are the homes of Side 2 and 5, and Side 4 and 6, respectively.
Side 1, also called Zahn is located at Lagrangian point 5 (L5), and serves as the Earth Federation's administrative center in space. It was also one of the first colonial Sides the Principality of Zeon attacked during the One Week Battle, the initial and bloodiest phase of the One Year War. Side 1 is home to several of the oldest colonies, among them Shangri-La, Londenion, Colony 30, Island Blade, Island Ease, and the Pia Albanian colony.
Side 2, also called Hatte, is located at L4. This was one of the first Sides attacked by the Zeon during the One Week Battle. Island Iffish, the colony that was dropped onto Earth during Operation British, was hijacked from Side 2. In the U.C. 150s, it became the home Side to the Zanscare Empire. Side 2 is home to Amelia, Macedonia, Blue 3, Calabria, Heras, Island Iffish, Colony 13, the 18th Block, and the 21st Block.
Side 3, also called Munzo, is located behind the Moon at L2. Side 3 was the only Side to never use the "open-type" colonies. They instead used "closed-type" colonies, which removed the glass "sky" panels and was a completely "solid" cylinder with no open view to space. This allowed each colony to house greater capacities of people.
Side 3 was the birthplace of the first Spacenoid rebellions and the concept of Newtypes. In U.C. 0052, Zeon Zum Deikun moved to Side 3 and began to spread his philosophy of Contolism - essentially that the earth was sacred, and that human beings had a solemn right to protect it. This philosophy also encouraged the people of the space colonies to consider themselves independent from Earth. In U.C. 0058, under the guidance of Zeon Zum Deikun, Side 3 declared independence from the Earth Federation and formed as a republic. In U.C. 0068, Deikun died under mysterious circumstances, and his deputy Degwin Zabi took control.
Under Degwin's leadership, Side 3 became a military dictatorship, and the National Guard regiments Side 3 maintained became a full fledged army. Degwin then announced the formation of the Principality of Zeon, setting himself up as the ruler and giving his four children unilateral control of the military forces. Simultaneous with this announcement came severe purges of the remaining followers of Zeon Zum Deikun living in Side 3. The Principality of Zeon began to mass-produce various warships and mobile suits in anticipation of an armed conflict with the Federation. In January 3, U.C. 0079, Zeon unilaterally declared war upon the Earth Federation, beginning the devastating One Year War.
After the Battle of A Baoa Qu and the downfall of the Zabi family, Side 3 came under the control of Prime Minister Darcia Bakharov, who pursued peace with the Federation and reached an agreement whereby the Principality of Zeon would surrender, and Side 3 would be allowed to maintain its independence under the name "Republic of Zeon". The deal also allowed the Republic to maintain an armed force which would be subject to periodic inspections by the Federation. Although the agreement formally ended the war, many Principality loyalists rejected the offer, and chose instead to go into hiding as remnant forces such as the Axis Zeon and Mars Zeon, as well as rogue militant groups such as the Invisible Knights, Delaz Fleet, Cima Fleet, African Liberation Front, Kimberlite Forces and Simbu Base Corps.
Side 3 received additional space colonies in U.C. 0082 and again in U.C. 0083 as part of the Colony Reclamation Project, which sought to ease the overcrowding of Side 3. Side 3 remained the Republic of Zeon until they rejoined the Federation in U.C. 0100. Other colonies in Side 3 are Tigerbaum, Bieutar and Achilles.
Side 4, also called Moore (sometimes spelt as Mua), was initially located at L5. During the reorganization of Sides in U.C. 0084, Side 4 was moved to L1.
Side 4 was one of the first colonies attacked by the Zeon during the One Week Battle, and is the location of the Thunderbolt Sector, a shoal zone created from the debris of mobile suits, ships and some of the destroyed colonies. Some experts have suggested that the colony used for Operation British originated here. Side 4 was eventually reconstructed into the Frontier Side, and was briefly invaded and occupied during the U.C. 120s by the Crossbone Vanguard to establish the short-lived Cosmo Babylonia. Other known colonies in Side 4 are New Manhattan, which was the headquarters of the Illuminati resistance group in G-Saviour, and Industrial 7, a closed-type industrial colony managed by Anaheim Electronics.
Side 5, also called Loum, was initially located at L1. During the reorganization of the Sides in U.C. 0084, Side 5 was moved to L4.
During the early phase of the One Year War, it became a battle zone when the Principality of Zeon attempted to conduct a second Operation British by dropping a colony from Side 5 onto Earth. When the Earth Federation Space Force made a stand to intercept the Zeon, a massive space battle erupted between the two forces, known to later history as the Battle of Loum. It was the first time mobile suits are used in large scale battles, and the battle ended with a decisive (but pyrrhic) victory for Zeon over the Federation fleet. Most of the colonies in Side 5 were either destroyed or heavily damaged, and most of the survivors fled the Side. At the end of the One Year War, this area became known as the shoal zone. Watohoat, the Texas Colony and the Garden of Thorns, headquarters of the Delaz Fleet were all located in Side 5.
Side 6, also called Riah, is located at L4. Side 6 declared autonomy from the Earth Federation on April U.C. 0077, and thanks to backing from the Principality of Zeon, succeeded in gaining self-governance, at which point this Side adopts the name Riah Republic. Unlike Side 3, which went to war to claim total independence from the Earth Federation, Side 6 maintained diplomatic ties with the Federation, and left the Earth Federation control on good terms. Side 6 declared neutrality in the opening weeks of the One Year War, and managed to avoid most of the conflict; however, the Federation maintained a secret R&D base there, and Side 6 was targeted by Zeon's Cyclops Team after it was discovered. It was also the place where a one-sided space battle between Federation's White Base team and Zeon's Conscon Fleet was televized to the entire Earth Sphere.
Side 6 would later rejoin the Earth Federation. During the reorganization of Sides in U.C. 0084, Side 6 was moved to L5. Many colonies are known to be located in Side 6: Ribo, Baldur Bay, Franchesca, Ontario, Ukraine, Kamiigusa, Palda, Morudeigan and New Madera.
Side 7, also called Noa, is located at L3. At the time of the One Year War, Side 7 was still being constructed and consisted of only a single, incomplete space colony that housed a Federation R&D base involved with the classified Operation V. This Side became famous in September of U.C. 0079, when the Federation assault carrier White Base and its RX-78-2 Gundam mobile suit successfully fended off an attack by Zeon Zaku IIs, and in doing so marked the first recorded battle between mobile suits inside a space colony.
After the One Year War, there are two known colonies in Side 7. The original Side 7 colony was completed and given the name Green Noa 1, and the side itself was renamed Green Oasis. A second colony, known as Green Noa 2, is added to the cluster in U.C. 0085. During the Gryps Conflict, Green Noa 1 was the site of a secret testing facilities for the "Black Gundams" and was attacked by the Anti-Earth Union Group. Green Noa 2 was codenamed "Gryps" by the Titans, half of the colony (later renamed Gryps II) being converted into a Colony Laser.
Side 8 is a late addition to the Universal Century timeline. The colonies, now referred to as "Settlements" are primarily focused on agriculture and are located at L1. One such Settlement is known as "Gaea". The leader of Gaea is Councilor Graves.
- Moon Moon: A lost "Island 1" type colony, home to a primitive group of space dwellers. Seen in Mobile Suit Gundam ZZ and Mobile Suit Moon Gundam.
- Sweetwater: It was created through the combination of an Island 3 "open-type" colony with a "closed-type" colony as a place for refugees of the One Year War, Gryps Conflict, and First Neo Zeon War. In U.C. 0093, Neo Zeon, now led by Char Aznable, used the colony as a base from which they could launch another war against the Earth Federation. Due to Aznable's popularity among the colonists, Neo-Zeon's existence was hidden from the inspections conducted by the task force Londo Bell until the commencement of the Second Neo Zeon War.
- Laplace: A Stanford Torus-type colony, used as the official residence for the prime minister of the Earth Federation. Destroyed in U.C. 0001.