Celestial body

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This article is for the PC version of Stellaris only.

Celestial body

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.

Planet size

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.

Planet capacity

Type	Planet capacity
Tomb World Habitat	+3
Relic World Machine World Ringworld All regular habitable planets	+4
Gaia World Ecumenopolis Hive World	+6

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

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, a species will have 80% habitability for planets of the same type, 60% habitability for planets of the same climate category, and 20% habitability for every other climate category and type. Finally, these habitability values can be both increased and decreased species-wide by certain traits and for a given planet by certain planetary features and planetary modifiers.

A planet's type also affects the set of possible planetary features and blockers it may have. Each of the three climate categories has a slight bias towards different resources when it comes to planetary features; Dry worlds (Desert, Arid and Savanna) are somewhat more weighted towards Energy deposits, Frozen worlds (Arctic, Tundra and Alpine) are somewhat more weighted towards Minerals deposits and Wet worlds (Tropical, Ocean and Continental) are somewhat more weighted towards Food deposits. Continental worlds in particular stand out, as they have a much stronger bias in favour of their preferred resource than the other types.

Type	Climate	Description
Arid	Dry	Dry, rocky world with a nitrogen-oxygen atmosphere. The dust-covered terrain consists largely of mesas and canyons. Forests can be found in the more temperate polar regions, but vegetation is otherwise scarce.
Desert	Dry	Dry, rocky world with a nitrogen-oxygen atmosphere. Precipitation and major bodies of surface water are relatively rare. Significant temperature variations between day and night cycles. Vegetation is scarce, but even moderate precipitation can make the desert bloom.
Savanna	Dry	Rocky world dominated by dry, arid plains covered by a nitrogen-oxygen atmosphere. The small hydrosphere allows for brief wet seasons, but aside from a few ubiquitous grasses vegetation is largely concentrated around shallow oases.
Alpine	Frozen	Mountainous world with a nitrogen-oxygen atmosphere. Snow covers the mountaintops and frozen-over lakes dot the valleys. While the planet experiences the minimal seasonal variations, the still-liquid water beneath the frozen surface of the lakes is enough to sustain some hardy vegetation.
Arctic	Frozen	Frigid, rocky world with a nitrogen-oxygen atmosphere. The poles are big, and significant water deposits can be found permanently frozen as glacial ice. However, the planet experiences seasonal variations and the equatorial band is covered by vegetation.
Tundra	Frozen	Cold and rocky world with a nitrogen-oxygen atmosphere. Permafrost covers most of the surface except for the more temperate equatorial regions. A stable biosphere exists but vegetation is mostly limited to mosses and lichens.
Continental	Wet	Rocky world with a nitrogen-oxygen atmosphere. Active and stable hydrosphere. Great landmasses are separated by oceans, with large climate variations depending on latitude and precipitation.
Ocean	Wet	Rocky world with a nitrogen-oxygen atmosphere and a significant hydrosphere. Oceans cover more than 90% of the surface, with scattered islands making up the remaining percentage.
Tropical	Wet	Humid, rocky world with a thick nitrogen-oxygen atmosphere. Seasons with significant precipitation are interchanged with drier periods. Most landmasses are covered in dense vegetation.

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 increased or decreased by effects such as traits. These planets feature their own set of rules regarding planetary features which are distinct from the regular habitable planets; Gaia worlds are biased towards spawning the highest-tier resource deposits, Relic worlds have their own set of unique planetary features and the other three (Ecumenopolis worlds, Hive worlds and Machine worlds) will remove all planetary features upon creation.

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
Gaia	Life-Seeded	World Shaper ascension perk Gaia Seeders Nu-Baol Life-Seeding decision	100% Habitability +10% Biological pop happiness +10% Lithoid pop happiness +10% Resources from jobs +50% Automatic Resettlement Destination Chance	Gaia Worlds tend to have positive modifiers and no negative ones. Most DLCs add at least one system with a Gaia world, but a few can be found in all versions: A system called Wenkwort will always spawn in the galaxy. It contains a size 19 Gaia world called Wenkwort Artem with the unique Wenkwort Gardens modifier. A size 25 Gaia world called Zanaam will occasionally spawn in a galaxy. It is defended by the Guardians of Zanaam. Four Gaia worlds with special names - Prophets Retreat, Walled Garden, Emerald Mausoleum, Pristine Jewel - border the systems of the Holy Guardians. They have the Holy World modifier and colonizing them will incur their ire. Destroying them will even awaken the Fallen Empire.
Tomb	Post-Apocalyptic	Armageddon bombardment Javorian Pox bombardment Relentless Industrialists buildings after the first Environmental Deterioration situation reach 100	0% Base habitability	Pre-FTL civilizations in the Atomic or Early Space Age have a small chance of starting a nuclear war and turning the planet into a Tomb World. Empires with the Determined Exterminator civic start on a Tomb World if they don't have the Resource Consolidation origin. Colonizing a Tomb World will displease the Traditionalist faction unless the empire has the Post-Apocalyptic origin. Each Tomb World has a high chance of triggering one of 8 unique events 2 or 3 years after the planet is colonized.
Ecumenopolis		Arcology Project decision Restore Ecumenopolis decision Cannot be terraformed again	100% Habitability +20% Resources from jobs +15% Pop growth speed +15% Pop assembly speed +50% Automatic Resettlement Destination Chance All building slots are unlocked Unique districts	Ecumenopolises have special districts. All normal planetary features are removed. Planetary Prospecting decision disabled. The only pre-existing Ecumenopolis is the homeworld of the Keepers of Knowledge Fallen Empire. The city lights of an Ecumenopolis are determined by the ship appearance of the terraforming empire. Empires that are Gestalt Consciousness (except Rogue Servitor) or have the Agrarian Idyll civic cannot take the ascension perk, but can still use conquered Ecumenopolises.
Relic	Remnants		80% Base habitability Allows the Restore Ecumenopolis decision	Relic Worlds can be found in the First League Precursors' home system or in various systems added in the Ancient Relics DLC. Relic Worlds contain unique planetary features that grant bonuses to research output. However, most of the surface is covered by blockers that are expensive to remove.
Hive		Hive Worlds ascension perk	100% Habitability if authority is Hive-Minded 0% Habitability otherwise +10% Resources from jobs +1 Spawning Drone job +6 Housing from Hive Districts +50% Automatic Resettlement Destination Chance All building slots are unlocked	All normal planetary features are removed. Resource districts are not limited by features. Planetary Prospecting decision disabled. The following planetary modifiers will also be removed: Atmospheric Aphrodisiac, Atmospheric Hallucinogen, Bleak, Hazardous Weather, Hostile Fauna, Irradiated, Lush, Natural Beauty, and Wild Storms.
Machine	Resource Consolidation	Machine Worlds ascension perk	0% Habitability, unless: Mechanical species Machine Unit species Cybernetic species, and owner is Driven Assimilator +10% Resources from jobs +1 Replicator job −10% Pop housing usage +50% Automatic Resettlement Destination Chance All building slots are unlocked Agriculture districts	All normal planetary features are removed. Resource districts are not limited by features. Planetary Prospecting decision disabled. The following planetary modifiers will also be removed: Atmospheric Aphrodisiac, Atmospheric Hallucinogen, Bleak, Hazardous Weather, Hostile Fauna, Irradiated, Lush, Natural Beauty, and Wild Storms. If the planet contains organic pops that don't have the Cybernetic trait when terraformed, they are killed and the Machine World gains an Organic Slurry planetary feature ( +15 Food).

Habitable megastructures

Habitable megastructures are artificial celestial bodies and can be constructed using resources after researching the required technology. They feature a fixed habitability value that is the same for every species and have unique districts and designations. They do not ordinarily have any planetary features on them.

Type	Source	Notes	Description
Habitat	Void Dwellers origin Megastructure construction	70% Habitability (90% with Voidborne) Uses special districts, with one variable district available only if built over a planet with a resource deposit Starts at size 4 and can be increased up to size 8 by decision, with the required technologies +200% Colony development speed Can only gain building slots from colony capital, certain technologies, and: 2 with Voidborne ascension perk 1 with Adaptive Ecology tradition 1 with Public Works tradition if Void Dwellers 1 with Functional Architecture or Constructobot civics	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.
Ring World	Repaired from broken segments Sanctuary system Repair the Shattered Ring decision Ancient Caretakers home system Megastructure construction	100% Habitability Segments destroyed by a crisis or World Cracker cannot be repaired Uses special districts All building slots are unlocked	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	100% Habitability Enables the Repair the Shattered Ring decision.	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 cannot be colonized or terraformed (unless it has the Terraforming Candidate modifier), but they can have various resource deposits. Toxic worlds can be terraformed only if the empire has the Detox Ascension perk. These celestial bodies do not spawn any planetary features on them, but they can sometimes have certain planetary modifiers applied to them.

Type	Deposits
Type	Minerals	Energy	Alloys	Trade Value	Engineering Research	Society Research	Exotic Gases	Rare Crystals	Volatile Motes	Zro
Asteroid
Ice Asteroid
Crystalline Asteroid
Barren World
Barren World (Cold)
Broken
Frozen World
Gas Giant
Molten World
Toxic World

Special uninhabitable planets

Special uninhabitable planets can only be created in unique systems or as a result of events. Once again, planetary features do not spawn on these worlds.

Type	Notes	Description
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	Can be created by using a World Cracker Colossus weapon on a planet. 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.

Stars

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. Different stars have different likelihoods for habitable planets to appear in the system, with F-type, G-type and K-type stars having the highest likelihood for habitable planets to appear around them and every other type having a lower likelihood of having habitable planets in orbit around them.

Most solar systems are unary systems with only one star, but they can also exist as binary systems with two stars or trinary systems with three stars, either orbiting each other in the center with all planets around them or spread out further apart from each with a few planets orbiting each star. The effects and chances for habitable planets stack in binary and trinary systems.

Type	Potential resources	Habitable planets chance	Description
Class B	Energy Physics	−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	Energy Physics	−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	Energy Physics		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	Energy Physics		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	Energy Physics		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	Energy Physics	−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	Energy Physics	−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	Energy Physics	−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	Engineering Physics	−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. 100% Shield Nullification Allows construction of a Quantum Catapult
Black Hole	Engineering Physics Dark Matter	−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. 50% Disengagement Chance Reduction +50% Emergency FTL Jump Cooldown Allows starbases to construct the Black Hole Observatory building. Allows construction of a Matter Decompressor
Neutron Star	Engineering Physics	−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. 50% Sublight Speed Reduction Allows construction of a Quantum Catapult
Viridescent Lightbringer	Volatile Motes Exotic Gases	−100%	Millennia of exposure to the Toxic Entity have caused alterations in the makeup of this star. Though once it was a fairly standard G-type star, now it emits an eerie green haze unlike anything seen elsewhere in the galaxy. 100% Armor Nullification This star type only appears in the system created at the completion of the Quest for the Toxic God situation. This system has two Toxic Worlds (size 30 and 20) with the Toxic Terraforming Candidates planet modifiers.