A celestial body is a star, planet, moon or asteroid present in a star system. Celestial bodies may have resources which can be harvested by orbital stations. Each start system can have between 2 and 15 celestial bodies.
When any owned ship enters a system or passes within its sensor range, any habitable planets in the system will be revealed along with their world type. To see further details about the celestial bodies in a system, it is necessary to survey them with a science ship. This will reveal all of the orbital resources associated with each planet or asteroid. For habitable worlds, this will also reveal more detailed world information including: size, available districts, planetary features and blockers (if any), and the habitability for each species in the player's empire. Additionally, surveying worlds has a chance to reveal anomalies.
The planet size determines the visual size of a planet and the maximum number of districts the planet can support if it's habitable. Planets can have various sizes, but habitable ones will always be within the following margins:
- Planets have a size between 12 and 25
- Moons have a size between 10 and 15
- Homeworlds have a size between 18 and 21, unless otherwise determined by the empire's origin.
Each colony has a planet capacity, which determines how many pops it can support before growth starts to slow down. Each unit of unused housing provides +1 planet capacity and each pop also provides +1 planet capacity. This has the result that on a planet with no modifiers to housing usage, the planet capacity will equal total housing, and modifiers that affect pop housing usage will also affect planet capacity. In addition, each unblocked and unused district slot will grant additional planet capacity depending on the world type (see table).
Habitable planets are the only natural celestial bodies that can be colonized and terraformed, without the Terraforming Candidate planet modifier. There are nine types of regular habitable planets, divided equally into three climate categories: dry, frozen and wet. Each type's base habitability for a given species depends on how closely it matches a species' homeworld: in general, 80% for same type, 60% for same category, and 20% for other category.
A planet's type also affects the set of possible planetary features and blockers it may have.
Special habitable planets
Special habitable planets are only spawned in certain systems, but any empire that meets the requirements can terraform a regular habitable world into a special one. Certain origins use one of these as the empire's homeworld. All of them have either very high or zero habitability, and most of them feature fixed habitability, meaning that habitability cannot be reduced by effects such as traits.
In addition to regular terraforming, some worlds can be terraformed by decisions such as Restore Ecumenopolis or Repair the Shattered Ring.
|Type||Origin Homeworld||Terraforming methods||Effects||Notes|
|Tomb||Post-Apocalyptic||0% Base habitability||
|Hive||Hive Worlds ascension perk||
|Machine||Resource Consolidation||Machine Worlds ascension perk||
Habitable megastructures are artificial worlds and can be constructed after researching the required technology. They feature the same habitability for every species and have unique districts and designations.
||An artificial deep-space arcology offering planet-like, if decidedly urban, living conditions. Hydroponics and advanced filtering technologies make it near-self-sustaining, and station-borne facilities can mine the station's host planet for raw materials.|
||An immense band encircling the system's sun. Built to allow for numerous artificial habitation zones along its inner span, freed from the restrictions and mundanity of planet-bound, spherical existence.|
|Shattered Ring World||Shattered Ring origin||An immense band encircling the system's sun. This section of the megastructure has sustained damage - especially to some of its more advanced districts - but it does not appear irreparable.|
Uninhabitable celestial bodies
All non-star celestial bodies that cannot harbor advanced organic life are classified as uninhabitable. These worlds can't be colonized or terraformed (unless it has the Terraforming Candidate modifier), but they can have various resource deposits.
Special uninhabitable planets
Special uninhabitable planets can only be created in unique systems or as a result of events.
|AI||These planets are created by the Contingency. They are similar in appearance to Machine Worlds, but are not habitable at all. Successful bombardment turns the planet into a broken world.||Rocky world covered with artificial structures. The thin atmosphere consists mostly of industrial pollutants. There are strong energy emissions coming from across the entire surface, but no organic life signs.|
|Cracked||Created by the hatching of the Voidspawn, destroying the existing colony. Has a deposit of 20 Society.||The cracked shards of an enormous planet-sized egg.|
|Infested||Created when habitable worlds are infested by the Prethoryn Swarm. Successful bombardment turns the planet into a barren world that can be terraformed.||The surface of this world is covered by some kind of biological contaminant.|
|Nanite||Found in the L-Cluster, with half of the outcomes giving them the Terraforming Candidate modifier once the nanite factory is destroyed.||A chaotic and inhospitable world, disfigured according to some mad design.|
|Shattered||All worlds will have a deposit of 4–16 Minerals.||The charred, broken remnants of what was once a planet. A massive energy surge has detonated this world's core, leaving only slabs of rock.|
|Shielded||Found through exploration, where the shield can be brought down through a special project with different possible outcomes. They can also be created using the Global Pacifier Colossus weapon but these worlds cannot then be un-shielded.||This entire world is encased in some kind of impenetrable energy barrier. It blocks all scans of the surface.|
|Shrouded||Created by the Teachers of the Shroud origin as well as the End of the Cycle and Eater of Worlds. Cannot be recovered. A few Shrouded Worlds can be found in some special systems.||Our sensors are unable to penetrate the thick fog surrounding the planet. Ships that enter it do not return.|
A star is a celestial body that composes the center of a star system and influences the generation of the solar system. They are classified based on their spectral characteristics. Less common stars also have a negative effect on all ships in the system, making certain tactics less effective in battle.
Most systems have only one star, but a few have two or three stars, either orbiting each other with the planets around them or far enough from each other that a few planets orbit each star. The effects and chances for habitable planets stack in binary and trinary systems.
|Type||Potential resources||Habitable planets chance||Description|
|Class B||−40%||The large class B main-sequence stars are very bright and blue. Although somewhat rare, the luminosity of these stars make them among the most visible to the naked eye.|
|Class A||−40%||These relatively young white or bluish-white main-sequence stars are typically among the most visible to the naked eye. They are large and rotate very quickly, but will eventually evolve into slower and cooler red giants.|
|Class F||F-type stars are fairly large and often referred to as yellow-white dwarves. Although they often emit significant amounts of UV radiation, their wide habitable zones have a good chance of supporting life-bearing worlds.|
|Class G||Often referred to as yellow dwarves, G-type stars actually range in color from white to slightly yellow. Main-sequence stars fuse hydrogen for roughly 10 billion years before they expand and become red giants. Although their lifespans are shorter than K-type stars, worlds inside the habitable zone of a G star often enjoy optimal conditions for the development of life.|
|Class K||These main-sequence stars, sometimes referred to as orange dwarves, are a fairly common sight. They are stable on the main-sequence for up to 30 billion years, meaning that worlds orbiting a K-type star have a longer than average window to evolve life.|
|Class M||−60%||The most common stars in the universe, often referred to as red dwarves. Their low luminosity means they are difficult to observe with the naked eye from afar. Although they typically have an extremely long lifespan, red dwarves emit almost no UV light resulting in unfavorable conditions for most forms of life.|
|Class M Red Giant||−90%||With a large radius and comparatively low surface temperature, red giants are stars of moderate mass in a late stage of stellar evolution. Their expanded stellar atmosphere and high luminosity make for distant habitable zone orbits.|
|Class T Brown Dwarf||−60%||Brown dwarfs are substellar objects that lack the mass to sustain hydrogen fusion. Roughly the size of large gas giants, they have a much greater density. Their low luminosity and comparatively small heat generation means that planets orbiting them are unlikely to support life.|
|Pulsar||−100%||Pulsars are highly magnetized neutron stars that emit beams of electromagnetic radiation. As the star rotates, the radiation beam is only visible when it is pointing directly at the observer. This results in a very precise interval of pulses, which sometimes is so exact that it can be used to measure the passage of time with extreme accuracy. The radiation emitted by pulsars interferes with deflector technology, rendering ship and station shields inoperable.
|Black Hole||−100%||Typically formed as a result of the collapse of a very massive star at the end of its life cycle, black holes have extremely strong gravity fields that prevent anything - including light - from escaping once the event horizon has been crossed. The gravitational waves emitted by black holes interfere with FTL drives, making it harder for ships to escape from combat.
|Neutron Star||−100%||These incredibly dense stellar remnants are sometimes created when a massive star suffers a rapid collapse and explodes in a supernova. Although their diameter is typically as little as ten kilometers, their mass is many times greater than an average G-type star. The gravitational waves and radiation emitted by Neutron Stars must be carefully navigated around, slowing the sublight speed of ships.