The Outer Planets: A Comparison

Uranus and Neptune are not simply smaller versions of Jupiter and Saturn. This table summarizes the key differences among the four Jovian planets.

	Interior	Surface	Rings	Atmosphere	Magnetic Field
Jupiter	Terrestrial core, thick liquid metallic hydrogen layer, molecular hydrogen	No solid surface, atmosphere gradually thickens to liquid state, belt and zone structure, hurricanelike features	Yes	Primarily H, He	19,000 × Earth’s total field; at its cloud layer, 14 × stronger than Earth’s surface field
Saturn	Similar to Jupiter, with bigger terrestrial core and less metallic hydrogen	No solid surface, less distinct belt and zone structure than Jupiter	Yes	Primarily H, He	570 × Earth’s total field; at its cloud layer, ⅔ × Earth’s surface field
Uranus	Terrestrial core, liquid water shell, liquid hydrogen and helium mantle	No solid surface, weak belt and zone system, hurricanelike features, color from methane absorption of red, orange, yellow	Yes	Primarily H, He, some CH₄	50 × Earth’s total field, at its cloud layer, 0.7 × Earth’s surface field
Neptune	Similar to Uranus	Similar to Uranus	Yes	Primarily H, He, some CH₄	35 × Earth’s total field, at its cloud layer, 0.4 × Earth’s surface field

For detailed comparisons between planets, see Appendices 1 and 2.

*To see the orientations of these magnetic fields relative to the rotation axes of the planets, see Figure 14-8.