01
Hot "ice"
The "ices" in ice giants are compressed under extreme pressure and heat — they behave as dense fluids, not the frozen ice you'd recognize.
Solar system · Question
What's actually inside a planet?
The eight planets aren't variations on one design — they're built from three genuinely different structures. Here's what's really underneath the surface of each type.
Visual model
Three cross-sections.
Terrestrial (rocky)
Mercury, Venus, Earth, Mars
- Solid rocky crust and mantle
- Dense metal (mostly iron) core
- Small, dense, few or no moons
Gas giant
Jupiter, Saturn
- Deep hydrogen and helium atmosphere
- Layer of liquid metallic hydrogen
- Small rocky/icy core, no solid surface
Ice giant
Uranus, Neptune
- Thinner hydrogen/helium atmosphere
- Deep mantle of water, ammonia, and methane "ices"
- Small rocky core
What's simplified
"Ice" doesn't mean what you think.
02
No sharp boundaries
Real planetary interiors transition gradually between layers — these diagrams draw clean rings for clarity, not because there's a hard edge.
Misconception check
Quick check.
Quick check
Go deeper
Keep exploring.
Next in this series →
Planet sizes ↗
Compare any two planets side-by-side.
Size
Compare any two planets
See exactly how much bigger a gas giant is than a rocky one.
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