Celestial body

Version

This article has been verified for the current PC version (3.10) of the game.

Celestial body

**Classification**

Colonization

Planetary features

Planet modifiers

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

* Machine World
* Habitat
* All regular habitable planets
* Ecumenopolis
* Hive World
* Ringworld

Each colony has a  Planet capacity, which determines the logistic pop growth bonus or malus from  pops. There are three sources of planet capacity:

1. Housing: Each unit of unused  housing provides  **+1** planet capacity.
2. Districts: Free district slots will grant planet capacity depending on the world type (see table). Clearing  tile blockers increases planet capacity. Building districts can alter planet capacity, depending on whether the housing bonus is higher or lower than the capacity bonus of the undeveloped district.
3. Pops: Every pop provides  **+1** planet capacity, but also uses housing. Therfore, only pops with  pop housing usage modifiers affect planet capacity, e.g. every pop with the  communal trait (and no other modifiers) provides  **+0.1** planet capacity in total.

# Planet capacity
∑
Unused housing
∑
Free districts
⋅
planet capacity bonus value
∑
pop

{\displaystyle \text{Planet capacity} = \sum \text{Unused housing} + \sum \text{Free districts} \cdot \text{planet capacity bonus value} + \sum \text{pop} }

A more static perspective would be from the point of view of total housing:

# Planet capacity
∑
Total housing
∑
Free districts
⋅
planet capacity bonus value
−
∑
(
housing usage modifier
⋅
pop
)

{\displaystyle \text{Planet capacity} = \sum \text{Total housing} + \sum \text{Free districts} \cdot \text{planet capacity bonus value} - \sum (\text{housing usage modifier} \cdot \text{pop}) }

 Planet capacity is capped at 500.

## 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 **100%** habitability for its homeworld, **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.

### 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*.

### 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 different districts and designations. They do not normally have any planetary features on them but may contain blockers.

* Knights of the Toxic God origin
* Megastructure construction
* Ithome's Gate system
* **50%** at tier II
* **60%** at tier III
* Can be upgraded by decision if the required technology is researched
* **+200%** Colony development speed
* Sanctuary system
* Repair the Shattered Ring decision
* Ancient Caretakers home system
* Megastructure construction
* **+50%** Automatic resettlement destination chance

## Uninhabitable celestial bodies

All non-star celestial bodies that cannot harbor advanced life are classified as uninhabitable. These worlds cannot be colonized or terraformed unless they have the  Terraforming Candidate modifier, but they can have various resource deposits. Astral Scars can only appear if the  Astral Planes DLC is installed.

### 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.

## 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.