Planetary orbits are categorized by zone, which are based on the solar radiation level at the planet's orbit distance from the sun.
The orbit zone of a planet is based solely on the sun it orbits; the effect of the other suns in binary and trinary systems is ignored within the scope of the game. Multiple suns illuminate the bodies in the solar system properly; they just don't affect the orbital zone.
The ecosystem of a body is based purely on its zone, not on the actual solar radiation that strikes its surface.
|Inferno||Molten. Too hot for water or hydrocarbons in the environment. Seas of magma prevail. Asphalt roads cannot be built here.|
|Inner||Hot. Planets may have seas of water and breathable atmospheres. Inner planets may host primitive plant and animal life near the seas. Can be readily colonized. No indigenous people exist in the wilderness.|
|Habitable||Warm. Solar output is just right for plants and animals to flourish. Habitable planets host an ecosystem of plant and animal life that is unique to the planet. Indigenous people readily move to cities from the wilderness.|
|Outer||Cold. Planets may have pronounced polar ice caps but seas will remain liquid near the equator. Outer planets may host primitive plant and sea life. Can be readily colonized. No indigenous people exist in the wilderness.|
|Frigid||Frozen. Extremely cold. Seas of frozen and semi-frozen gases prevail.|