Planetary Classification

Rocky, Atmospheric & Gas Giant Bodies

Body Type Atlas

Sizes shown are illustrative. In reality, gas giants are typically 5–10× the radius of rocky bodies. See the reference table for the full ED classification including helium-rich and Class IV variants.

How Worlds Are Classified

Bodies are sorted by composition, atmosphere, and surface state. Mass and temperature determine which volatiles can exist — close-in worlds lose light gases, distant ones retain frozen ices.

Gas giants follow the Sudarsky scheme (Classes I–V) which sorts them by equilibrium temperature and the resulting cloud chemistry — ammonia clouds when cold, water clouds when warm, sodium and silicate vapours when hot.

Habitability Markers

Earth-like World — Liquid H₂O + breathable N₂/O₂ atmosphere

Water World — Liquid surface, may host life — atmosphere varies

Ammonia World — Cold biosphere candidate — NH₃ in liquid state

Gas G. with Life — Floating microbial life in cloud layers

ELWs and ammonia worlds pay the highest exploration premiums.

ED: Scanning & Discovery

The Full Spectrum Scanner detects every body. The Detailed Surface Scanner gives the first-mapped bonus and confirms surface features for landable bodies.

Landable bodies require no significant atmosphere — typically icy, rocky, HMC, and metal-rich. Atmospheric landings are limited to thin-atmosphere bodies in Odyssey-equipped builds.

Look for valuable hand-ins: ELW, water world, ammonia world, and terraformable HMC all yield the largest cartographic credits.

ED Body Type Reference

Type	Composition	Atmosphere	Note
Icy body	H₂O / CH₄ / NH₃ ices	Thin / none	Common in outer reaches of systems
Rocky body	Silicate basalts	Thin / none	Mercury / Mars analogues
Rocky-ice body	Mixed silicate + ice	Thin / none	Transitional outer-system body
High Metal Content	Silicates + heavy metals	Thin (CO₂, SO₂)	Most common landable type — Venus-like
Metal-rich body	Iron, nickel, dense metals	None	Mercury-like, near-stellar
Earth-like world	Silicate + liquid H₂O	N₂/O₂	Habitable — extremely rare
Water world	Silicate + liquid H₂O	Variable	Liquid surface, possible life
Ammonia world	Silicate + liquid NH₃	NH₃ / CH₄	Cold biosphere candidates
Water giant	Massive H₂O envelope	Steam / supercritical	Bridge between water worlds & gas giants
Class I gas giant	H₂ / He + NH₃ clouds	Cold ammonia clouds	Jupiter analogue
Class II gas giant	H₂ / He + H₂O clouds	Warm water clouds	Pale, high albedo
Class III gas giant	H₂ / He, no condensates	Cloudless	Deep blue, Neptune-like coloration
Class IV gas giant	H₂ / He + alkali metals	Hot sodium/potassium	Tan/orange hot Jupiter
Class V gas giant	H₂ / He + silicate clouds	Glowing silicate	Extreme hot Jupiter, near-stellar
Helium-rich gas giant	He-enriched envelope	Hydrogen depleted	Rare evolved gas giant
Helium gas giant	Almost pure He	Negligible H	Extremely rare; fully evaporated H envelope