Diffuse Core
Heavy elements mixed with hydrogen · 7–25 Earth masses · Extends 30–50% of radius · May have been disrupted by ancient giant impact

Metallic Hydrogen
Hydrogen compressed to liquid metal state · Generates magnetic field via eddy currents · Extends to ~80% of radius

Molecular Hydrogen
Supercritical fluid — gradual gas-to-liquid transition · No distinct surface boundary

Cloud Layer
Three-tiered: water → ammonium hydrosulfide → ammonia crystals · 50 km thick

Upper Atmosphere
Stratosphere and thermosphere · Auroral emissions at poles · Temperature inversion