Non-Luminary World Classification Scheme

worldbuilding
Image from Steve Bowers

The Non-Luminary World Classification Scheme, or NoLWoCS, is a near standard classification method used to identify the many different forms of planetary bodies, minor worlds, and artificial structures that have evolved naturally or that have been created by the many societies and cultures of the Terragen Sphere. While every world or megastructure is, in its own way, unique, there are certain characteristics that can be used to identify and classify these places. The purpose of NoLWoCS is to provide an easy, "at a glance" platform for the common User, whereby he might find the navigation of the Sphere, virtual or real, a little easier.

  • NoLWoCS is divided into three tiers of classification: Class, Type, and Subtype. The different Classes of worlds are dependent on size, overall characteristics, and status of a planet. For instance, Planetoidal and Terrestrial world Classes are divided according to size, just as Terrestrial and Jovian worlds are different Classes because of their general characteristics, and of course, artificial worlds are different from all of these because they are not naturally occurring.
  • World Types are dependant on a variety of factors, but generally the compositional elements, which often lead to different planetary features and behaviors, are of sufficient difference to separate these worlds. Subtypes are much more specific, and often are the result of what would normally be considered minor planetary features. For instance, Gaian worlds are divided into several different Subtypes based on items such as the amount of surface water, atmospheric composition, and so on.

Orbital and Rotational Parameters

Eccentric worlds and Tilted Worlds

Worlds of any class that have unusually high tilts or unusual orbits are classed as Skolian, Janusian or Ikarian worlds.
  • Skolian Type Worlds Worlds with axial tilts greater than 45 degrees; any class of world can have Skolian characteristics. More information here
  • Janusian Type Worlds Worlds in resonant orbits which regularly exchange momentum. More Information here
  • Ikarian type worlds Worlds with eccentric orbits, with an eccentricity greater than 0.35. Any class of world can have an Ikarian type orbit. More Information here.

Asteroids

General asteroid image
Image from John Dollan

ASTEROID CLASS: non-spherical worlds of extremely low mass

The Asteroidal Class is the most basic, and the most numerous, of all the classes in the NoLWoCS. There are, of course, even more numerous smaller objects, namely meteoroids and space dust, and these are the ultimate building blocks of any solar system. But only asteroids can be considered worlds in their own right. By NoLWoCS definition, these are worlds from 50 meters to 50 kilometers in diameter. More Information here.

Types of Asteroid

  • Carbonic: Almost exclusively of carbon compound construction, resulting in the formation of bodies from pockets of high carbon material around later generation stars choked with heavier elements; common near the galactic core. They may also form in systems where two white dwarfs have spiralled together, and the resulting circumstellar disk coalesces into bodies high in carbon.
  • Metallic: More Information here
  • Carbonaceous: More Information here
  • Silicaceous: More Information here
  • Hydronic: Located close to the system's snow-line, these are silicaceous bodies with high instances of subsurface volatiles, typically in the form of water ice. Polar deposits in permanently shadowed regions may also be present.
  • Gelidic: Located beyond the snow line of their system, these are bodies with high instances of ice, ranging from water to methane to carbon dioxide, and many other compounds besides, surrounding a core of silicate rock. The smaller bodies may be a nearly homogeneous mixture of ice and rock, due to the lack of a mass great enough to have caused layer differentiation early in the formative period. See also Centaurian Type
  • Oortean: More Information here.
  • Vulcanian: More Information here.

Minor Planets (Planetoids)

Planetoidal
Image from John M. Dollan

PLANETOID CLASS: worlds with enough mass to pull themselves into spherical or near-spherical shapes

Generally, rocky (more rarely metallic or icy) bodies, either irregular or regular in shape, mostly large asteroids, some small moons, about 51 to 1,000 km along the longest axis. More information here.

Types of Planetoid

  • Carbonean type: Carbon worlds of this mass have a chance to form around stars whose proto-stellar disks have developed carbon pockets within them, but they are far more common about late generation, high metal stars or even as the results of secondary planetary formation around high carbon stars such as white dwarfs. However, worlds of this size and mass also experience some differentiation during their formation. The cores of such worlds are dense masses of condensed graphite, though the planetoids at the higher mass range could form cores of partially crystallized diamond.
  • Hadean Type: More Information here.
  • Hygiean: These bodies are typically quite dark, with albedos ranging from 0.03 to 0.1. While there can be deposits of water ice or other volatiles beneath the surfaces of these planetoids, the surfaces are more often marked by craters and large boulders. These worlds are less dense and more easily disrupted by major impacts. The larger bodies, however, will have been differentiated through the formation process, and can have small cores of iron, with a dense mantle or rock and a crust of lighter silicates. The smaller worlds, though, may be a relative even mixture of sparse metals and the far more common silicate rock.
  • Cerean Type: More Information here.
  • Chronian type: Named after the plethora of such bodies orbiting the planet Saturn, these can be a highly varied lot. Typically, these worlds are small and heavily cratered bodies untouched by time, save for the numerous impacts that they have suffered. Their low mass and composition of primarily ice, with small rocky cores, are simply too small for sustained geological activity. As such, there is an absence of atmosphere, or related surface features. However, certain disruptions, such as through tidal flexing or other massive external forces may initiate geological forces that can completely resurface a planetoid, as well as form a minor atmosphere. If such active worlds are positioned properly in a gas giant system, an impressive ring system may even be formed.
  • Vestian Type: More Information here.
  • Kuiperian Type: More Information here.

Terrestrial worlds

Terrestrial
Image from John M Dollan

TERRESTRIAL CLASS: worlds with an active internal geology that lasts one million years or more: 0.05 to 2.5 x Earth's mass

  • Adamaean: Carbon Worlds. Carbon-rich terrestrials. More information here
  • Ferrinian: Iron-rich, dense worlds. More information here
  • Hermian: Dense, inner system worlds. More information here
  • Selenian: Worlds with little or no metallic core.More information here
  • Cytherean: Hot, greenhouse worlds. More information here.
  • PelaCytherean: Terrestrial sized hot ocean worlds with thick atmospheres. More information here.
  • LithicGelidian: Worlds with a mixed rock and ice composition. More information here.
  • Europan: Icy worlds with a subcrustal ocean. More information here.
  • Titanian: Icy worlds with thick atmospheres. More information here.
  • Ymirian: Worlds made almost entirely of ices. More information here.
  • Vesperian: Tidally locked terrestrial worlds. More information here.
  • Hephaestian: These are the most active of planets, with surfaces that are almost entirely molten and a geology that changes on a yearly basis. The atmospheres of these planets vary greatly according to the world's size and mass, from having thick, Cytherean-like atmospheres to almost non-existent ones, where the feeble gravity loses any elements almost as soon as they are released from the surface. These worlds are generally heated by tidal flexing, by proximity to a star or as a moon of a gas giant. Example: Io.
  • Amunian Type: Cold, dry worlds with high levels of ammonia in the atmosphere but little water. May develop an ammonia-based biosphere (see the Soft Ones xenosophonts for one example).
  • Vitriolic Type: Worlds with lakes, seas or oceans of sulphuric acid; often with life, More information here.

Arean
Image from John M Dollan

Mars-like Worlds
  • Arean type: Mars-like worlds where the atmosphere and hydrosphere has largely disappeared due to the cessation of magnetic activity. .More information here.
  • EoArean subtype Young Mars-like Type planet with substantial atmosphere and surface water. More information here
  • AreanLacustric subtype: Young Mars-like worlds with moderate amounts of ocean cover . More information here.
  • AreanXeric subtype Mature, unusually hot and dry Arean type worlds. More information here.
  • AreanTundral subtype Cold Arean type worlds, often with considerable reserves of ice More information here.
  • EuArean Subtype Typical mature Mars-like world with minimal atmosphere and hydrosphere More information here.

Nova Terra again
Image from Steve Bowers

Earth-like Worlds

  • Gaian Type: Any Earth-like terrestrial world, of which there are many diverse forms depending on water content, composition and temperature. More information here
  • EoGaian Subtype: Young terrestrial worlds; these may develop into Gaian, Cytherean or Arean worlds later More information here
  • MesoGaian Subtype: Earth-like worlds with primitive biospheres More information here
  • Eugaian Subtype A mature Gaian world with life, also known as a Garden World More Information Here
  • GaianTundral Subtype: Cold Gaian worlds with periodic, or persistent, ice ages More Information Here
  • Campian Subtype: Dry Gaian worlds with 25% to 50% ocean cover More Information Here
  • Paludial Subtype: Humid Gaian worlds with 25% to 50% ocean cover More Information Here
  • Lacustric Subtype:Humid Gaian worlds with low topography and 50-80% ocean coverage; some of these worlds have extensive rainforest-type biomes More Information Here.
  • Chlorogaian (Halogenic) type: Gaian worlds with high levels of atmospheric chlorine. More: Chlorine Worlds.
  • To'ul'hese Worlds: These worlds are essentially Gaian versions of the Cytherean worlds. Thick and dense atmospheres, as well as a large amount of water, create high surface pressures and high temperatures. Life arises and adapts to these conditions, and can become quite diverse indeed. In one known instance, it has lead to an independent form of sapient life. More: To'ul'hian Worlds.
  • Pelagic Subtype Gaian worlds where oceans cover the surface anywhere from 85 to 100%. More Information here
  • EuPelagic Subtype Gaian worlds where shallow oceans cover the surface anywhere from 85 to 100%. More information here
  • BathyPelagic Subtype: Gaian worlds where deep oceans cover the surface anywhere from 85 to 100%. More information here.
  • PelaGelidic Subtype, ice covered ocean worlds More information here.
  • TundralPelagic subtype, partially ice covered ocean worlds More information here.
  • Xeric subtype Dry worlds with less than 25% ocean cover More information here.
  • HyperXeric subtype Very dry worlds with less than 10% ocean cover More information here.
  • PostGaian subtype: Old Gaian Worlds that are losing their biosphere and hydrosphere More information here.

Superterrestrials

Fira
Image from Steve Bowers

SUPER-TERRESTRIAL CLASS: worlds that are moderately massive, intermediate in mass between Terrestrial worlds and Gas Giants

More details here.

This class of worlds is both numerous and varied; most types of terrestrial worlds also exist as superterrestial types, but with higher gravity and greater mass which can profoundly affect the conditions on the surface.
Among the most common types of superterrestrial are SuperHermian, SuperCytherian and SuperGaian types, as well as the more unusual types listed below.
  • Pyrothalassic Type: Hot superterrestrials More information here
  • Pyrohydrothallasic Type - Hot waterworlds More information here
  • Panthalassic Type: Giant Waterworlds More information here
  • Nebulous Type: Superterrestrials with thick, helium-rich atmospheres. Helium worlds of this kind often have superrotating atmospheres; those which are tidally locked often have wildly assymetric weather patterns.
  • Gas Dwarfs. Example Kepler 11b
  • Other types of superterrestrial planets include certain hyperbarian and chthonian worlds, some of which have very sparse atmospheres indeed.

Gas Giants

Jovian
Image from John M Dollan

Gas Giants (also known collectively as Jovian worlds) form beyond the snow line, and have very large fluid envelopes compared to their cores. Some rare, and very ancient gas giants formed around the first generation of very low metallicity stars and have almost no rocky or metallic component. Gas giants are classified in two ways- by temperature, which affects the composition of the cloud layers of the giant in a number of significant ways, and by mass. Examples of each of the temperature classes can be found in any of the size classes, and vice versa, although some size classes are more common at certain temperatures and vice versa.

A typical gas giant may be classified using both size and temperature types to create a subtype, so the full classification might be Meso-EuJovian Subtype(This is the full classification for Jupiter) or Super-HyperthermalJovian Subtype (the full classification for Behemoth, Hat-P-1B).

Gas Giant Size Classes

Neptunian Class: 0.03 to 0.2 Jupiter masses

  • MicroJovian Type Small gas giants, with minimal solid core. More information Here .
  • SubJovian Type Medium sized gas giants, 0.08 to 0.2 Jupiter Masses. Many worlds of this type are outer system cryojovian worlds like Neptune and Uranus. More information here.
  • Hot Neptunes - a numerous class of world, which may be MicroJovian or Subjovian in mass, and EpiStellar or Hyperthermal in temperature More information here.

Jovian Class: 0.2 to 13.0 Jupiter masses

  • Mesojovian Type Major Type of Jovian Class of planet. Masses from 0.21 to 8.0 that of Jupiter More information here
  • SuperJovian Type Jovian worlds with masses from 8.1 to 13.0 that of Jupiter, the theoretical upper limit of planets. Objects more massive than this are classed as Brown Dwarfs. More information here.

Gas Giant Temperature Types

  • HyperthermalJovian Type: Very hot gas giants, with temperatures above 1400 Kelvin. Includes so=called 'Puffy worlds' and 'Comet worlds'. More Information here.
  • EpiStellar Jovian Type: Hot, dark gas giants with temperatures between 900 Kelvin and 1400 Kelvin. More information here
  • AzuriJovian Type Warm clarified blue gas giants with temperatures between 350K and 800K. More information here.
  • HydroJovian Type: Temperate gas giants with clouds predominantly consisting of water vapour. More information here.
  • EuJovian Type: Cool gas giants, with clouds predominantly consisting of ammonia. More information here.
  • CryoJovian Type: Cold gas giants in the outer reaches of a planetary system, generally too cold for clouds to form at all. More information here.

Other World Classes

  • HyperBarian Class: Very dense planets with cores up to 100 x Earth's mass. More information here.
  • Chthonian Class: Gas giant worlds, formerly HyperthermalJovians, which have lost their volatiles through evaporation. More information here.
  • Stevensonian Class Planetary mass objects which are found in interstellar space. More information here.

ARTIFICIAL CLASS

The artificial worlds found within the Terragen Sphere have almost all been constructed by humans and their mind-children; some, such as the Black Acropolis, are much older. Artificial worlds fall into two broad categories- those that rotate to produce artificial gravity, and those that do not.

  • Rotating Space Habitats Habitats constructed using conventional materials - includes Paired Habitats, Stanford Tori, O'Neill Cylinders, Bernal Spheres, Bishop Rings. More information Here.
  • Banks Orbitals and Ringworlds - Rotating habitats made from exotic materials (see Banks Orbitals).
  • Non Rotating Space Habitats - often used by space adapted clades; can be very large, but they are limited by their density- if they are too dense they will undergo self-gravitational collapse. More information here.
  • Ederworlds More information here.
  • Supermundane Worlds -worlds dynamically suspended above planets and stars. More information here
  • Freespheres - microgravity balloons containing atmosphere -can be very large indeed. More information here.
  • Dyson Swarms and Spheres Many variants of this type of construct are described here.

 
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Development Notes
Text by John M. Dollan, with additions by Steve Bowers

Initially published on 23 November 2004.