Rocky Core
Iron, nickel and silicates · ~1.2 Earth masses · Pressure ~7 Mbar (700 GPa) · Temperature ~5,400 K · Similar to Uranus's core but slightly larger

Icy Mantle
Hot dense supercritical fluid of water, ammonia and methane · 10–15 Earth masses · High electrical conductivity · Ionic water layer · Diamond rain likely occurs

H₂/He Envelope
Hydrogen-helium gaseous envelope · 5–10% of total mass · Extends 10–20% toward center · Gradual transition to liquid interior · Increasing methane concentration deeper

Cloud Layers
Methane ice crystals (upper), hydrogen sulfide, ammonium hydrosulfide (mid), water clouds (deep) · Methane absorbs red light → deep blue color

Thermosphere
Stratosphere → thermosphere at very low pressure · Contains carbon dioxide and water from meteoritic impacts · Transitions to exosphere