Codex Gamicus
Basic Information

A Planet is currently defined by the International Astronomical Union as an interstellar object that must meet three criteria:

  • It must fall into one of the three current definitions of planet composition : Terrestrial Planet, Gas Giant or Ice Giant
  • It must orbit a star (in our cosmic neighborhood, the Sun, or Sol, is our star). Stellar objects that do not orbit a star are called Rogue Planets, while objects that orbit a much larger body (such as a body in orbit of a gas giant) tend to be called "Moons", or natural satellites, even if they would be called Planets were they to be found in orbit of a star, away from such a gas giant.
  • It must be big enough to have enough gravity to force it into a spherical shape, in a process called isostatic adjustment. This takes millions of years. Generally, stellar objects that do not fit this criterion are called asteroids.
  • It must be big enough that its gravity has cleared away any other objects of similar size near its orbit. Stellar objects that have not met this criterion are called Dwarf Planets.

It is likely that our definition of the word Planet will evolve over time as humanity explores the cosmos.

In video games[]

Planets in video games tend to be represented as population centers and are the main exploitable resource points within a solar system.


In Stellaris, planets can be exploited for research, minerals, or energy. Certain planets can also be colonized. Planets are categorized as follows:

  • Alpine World
  • Arctic World
  • Arid World
  • Barren World
  • Continental World
  • Desert World
  • Molten World
  • Ocean World
  • Relic World
  • Savanna World
  • Tomb World
  • Tundra World