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A World or Planet is an astronomical body located in the void, usually orbiting a star.

  • The IISS also uses these astrographic terms near interchangeably.

Library Data Referral Tree[edit]

Please refer to the following AAB Library Data for more information:

Description (Specifications)[edit]

The term world refers to the various bodies that are contained in a stellar system; it encompasses planets, satellites, and asteroid belts. For example, the single most important world in a system may not be a planet; it could be a satellite of a gas giant, or it could be a planetoid within an asteroid belt. [1]

Planets possess a vast variety of identifying characteristics and can be categorized in many different ways. Some of the most common ways include: size, composition, exotic, and special natures.

Basic Planetary Types (Composition)[edit]

Planetary Characteristics (Composition)
Type Nickname Composition Remarks
Terrestrial World: Silicate world Ice Ball Icy or rocky world. Ice or light silicate rock. Density of 1.3 to 3.0 gm/cc^3, Borean World.
Terrestrial World: Low Iron world Rock Ball Rocky world. Heavy silicate rock, light metals. Density of 3.1 to 4.5 gm/cc^3
Terrestrial World: Medium Iron world Rock Ball Rocky world. Moderate mixing of iron and denser metals with silicate rock and lighter metals. Density of 4.6 to 6.0 gm/cc^3. Terra is a Medium Iron world.
Terrestrial World: High Iron world Iron Ball Metal world. Mostly iron and denser metals with a few silicate rocks. Density of 6.1 to 7.0 gm/cc^3
Terrestrial World: Metallic world Iron Ball Metal world. Entirely iron and other dense metals. Density over 7.1 gm/cc^3
Jovian World Gas Ball Mostly gases & some solids. Typically Gas Giants. Technically means huge world. Satellites of gas giants are known to have moons that can be habitable to conventional life. Jupiter is a gas giant.

Basic Planetary Types (Size)[edit]

Planetary Characteristics (Size)
Type Code Size Atm Hyd Pop Gov Law Remarks
Tiny World None 0RD -- -- -- -- -- (Dwarf World, Planetesimal, Planetoid, etc.)
Small World None S12 -- -- -- -- -- (Planetoid, Protoplanet, etc.)
Meso World None 345 -- -- -- -- -- (Mesoplanet)
Macro World None 678 -- -- -- -- -- Roughly Earth-sized.
Big World None 9AB+ -- -- -- -- -- A Super-Earth...
Gas Giant SGG SGG -- -- -- -- -- Small (SGG) gas giant.
Gas Giant LGG LGG -- -- -- -- -- Large (LGG) gas giant.

Exotic Planetary Types[edit]

These are Strange Worlds:

  1. Double World (Double Planet)
  2. Rosette World
  3. Doughnut World (Toroid World)
  4. Ellipsoid World
  5. Mobile World
  6. Ring Moon
  7. Ring World
  8. Rogue World
  9. Sphere World
  10. Tent World
TC Exotic World Series (Rarity) (IISS Scout Handbook, pgs. 490-491)
Type Code Size Atm Hyd Pop Gov Law Remarks
Double World None -- -- -- -- -- -- Double-planet mainworld.
Doughnut World None -- -- -- -- -- -- Toroidal world. A world with a hole in the center...
Ellipsoid World None -- -- -- -- -- -- Egg-shaped world.
Mobile World None -- -- -- -- -- -- Mobile world, whether natural or artificial, with added engines. Planetoid starships exist at TL-15.
Ring World None -- -- -- -- -- -- Artificial ring world. Megastructure.
Rogue World None -- -- -- -- -- -- Extrasystemic world. Thought to be very rare.
Sphere World None -- -- -- -- -- -- Artificial planetoid.
Tent World 0-2 -- -- -- -- -- -- A tented & paraterraformed world. Artificially constructed using Paraterraforming.

Special Planetary Types[edit]

  1. Locked World
  2. Main World
  3. Satellite World
  4. Twilight Zone World
TC Exotic World Series (Rarity) (IISS Scout Handbook, pgs. 490-491)
Type Code Size Atm Hyd Pop Gov Law Remarks
Locked World Lk -- -- -- -- -- -- Locked close satellite. Gravitational relationship.
Main World Mw -- -- -- -- -- -- Socioeconomic center of a system.
Satellite World Sa -- -- -- -- -- -- Satellite or moon. Gravitational relationship.
Twilight Zone World Tz -- -- -- -- -- -- Twilight Zone. Orbit 0-1. Gravitational relationship.

History & Background (Dossier)[edit]

Scientist argue about a variety of celestial objects and are constantly defining and redefining what is and isn't a planet:

  • Planetary-Mass Object (PMO)
  • Planemo
  • Planetary body
  • Dwarf planet
  • Protoplanet
  • Small Solar System Body (SSSB) [Minor planet]

The Solomani are particularly contentious in this area and the IAU (International Astronomical Union) definition of planet has fluctuated many times over the millennia.

Physical Planetology[edit]

This planetary grouping organizes by physical characteristics:

  1. Asteroid Belt World
  2. Big World
  3. Cold World
  4. Desert World
  5. Fluid World
  6. Frozen World
  7. Garden World AKA Terran Prime World
  8. Hell World
  9. Hospitable World
  10. Hot World
  11. Ice World
  12. Inferno World
  13. Inner World
  14. Inhospitable World
  15. Locked World
  16. Meso World
  17. Ocean World
  18. Outer World
  19. Panthallasic World
  20. Planetoid Belt World
  21. Rad World
  22. Small World
  23. Storm World
  24. Temperate World
  25. Tiny World
  26. Tropical World
  27. Tundra World
  28. Twilight Zone World
  29. Vacuum World
  30. Water World
  31. Worldlet

Socioeconomic Planetology[edit]

This planetary grouping organizes by socioeconomic characteristics:

  1. Agricultural World Series (Foodstuffs)
    1. Agricultural World
    2. Farming World
    3. Nonagricultural World
    4. Preagricultural World
  2. Colony World Series (Subjugation)
    1. Colonizer World
    2. Colony World
    3. Military Rule World
    4. Penal Colony World
    5. Prison World
  3. Industrial World Series (Manufacturing)
    1. Industrial World
    2. Mining World
    3. Nonindustrial World
    4. Preindustrial World
  4. Population World Series (Sophonts)
    1. Average Population World
    2. Lo Population World
    3. Hi Population World
    4. Pre-high Population World
  5. Socioeconomic World Series (Wealth)
    1. Main World
    2. Golden World
    3. Nexus World
    4. Poor World
    5. Pre-rich World
    6. Rich World
    7. Satellite World
    8. Silver World
  6. Technology World Series (Tech)
    1. Low Tech World
    2. Average Tech World
    3. High Tech World

Biological Planetology[edit]

This planetary grouping organizes by bioplanetological (life-bearing) characteristics:

  1. Barren World
  2. Die Back World
  3. Garden World
  4. Home World
  5. Hospitable World
  6. Inhospitable World
  7. Reserve World

Bioplanetological Sciences[edit]

Bioplanetological Sciences
Science Actor
Xenobiology Exobiologist The study of creatures, pre-sophonts, or lower intelligent lifeforms.
  • In a greater sense applies to all life, but is usually applied this way.
Sophontology Sophontologist The study of sophonts or intelligent lifeforms. Includes Proto-sophonts
Terraforming Terraformer A planetary engineering process which, over many years, converts a hostile world (Inhospitable World) into a livable one (Hospitable World).

Planet vs. World[edit]

What are the technical differences between the terms planet and world? In common usage, they are used interchangeably, but how do IISS scouts use the terms?

Planet vs. World
Term Remarks
Planet Denotes an astronomic and astrographic meaning and applies to all of the bodies in a system.
World Denotes a socioeconomic and sophontilogical meaning and mostly applies to those bodies with sophont populations, usually main worlds or satellite worlds.

References & Contributors (Sources)[edit]

This list of sources was used by the Traveller Wiki Editorial Team and individual contributors to compose this article. Copyrighted material is used under license from Far Future Enterprises or by permission of the author. The page history lists all of the contributions.