Planetary Classes

Planets made of classical matter are classified into 26 categories, 21 of which lay on the main sequence of planets. The planetary main sequence lists most kinds of planets and moons with exceptions being man-made or anomalous classes; they are typed on composition, geography, energy, habitability, and value to a sapient civilization. home
 * Class A | Metallic - Silicate-metallic planets with little to no atmosphere and geologic activity.
 * Class B | Geoinactive - Icy silicate/metallic planets with no atmosphere and no geologic activity.
 * Class C | Barren - Rocky, airless worlds with many craters; commonly a failed gas planet.
 * Class D | Geocrystalline - Lifeless Class M worlds with active volcanism and liquid water present.
 * Class E | Magmatic - Completely geoplastic worlds of molten silicates and metals, volcanic atmosphere.
 * Class F | Geometallic - Volcanic or barren planets with atmospheres that are marginally habitable, sometimes with primitive life.
 * Class G | Carbonic - Cold planets with thick hydrocarbon haze and methane seas and oceans; sometimes with exotic lifeforms.
 * Class H | Arid - Laying on the warm edge of the habitable zone and having some surface or subsurface water, some oxygen.
 * Class I | Neptunian - "Ice giants" with hydrogen, helium atmospheres, hydrodyolium layers, and extreme weathering.
 * Class J | Jovian - Huge gas giants with vast hydrogen atmospheres and massive hydrodyolium oceans beneath; rocky core.
 * Class K | Desert - Planets with vast sandy/salty plains that lay within the habitable zone but lack water or oxygen.
 * Class L | Marginal - Tidally locked Class M worlds, with one half of the planet scorched, one half frozen, and a habitable twilight zone.
 * Class M | Terran - Habitable planets that have oxygen, active geology and biospheres, and magnetic fields.
 * Class N | Toxic - Exceedingly hot planets with nearly all of the atmosphere being volcanic greenhouse gas.
 * Class O | Oceanic - Class M planets with more than 80% surface being water oceans.
 * Class P | Glaciated - Planets with more than 80% surface being water ice, has subsurface oceans and geology.
 * Class Q | Variable - Planets with extreme seasons due to variable output of a star, an eccentric orbit, or an unstable tilt.
 * Class R | Obscuric - Habitable worlds kept warm only by greenhouse gas and geologic activity, but with very little light.
 * Class S | Sempernimbus - Habitable worlds covered by perpetual water precipitation and cloud cover.
 * Class T | Uranian - Ice giants with helium methane/ethane atmospheres, and some ethonoldyolium oceans.
 * Class U | Anomalous - Any planet that does not fall within the classical planetary classification system.
 * Class V | Vegetated - Habitable planets with more than 80% of surface area being lush vegetation coverage.
 * Class W | Ecumenopolis- Planets with more than 80% of surface area being urban, industrial or metropolitan spread.
 * Class X | Electroactive - Exotic worlds with nearly endless lightning and auroras, sometimes habitable.
 * Class Y | Postnuclear - Irradiated and dusty planets that have suffered a catastrophic nuclear fallout.
 * Class Z | Georeactor - Planets with exceptional amounts of precious and heavy elements, sometimes oceans of metal.