21. Giant Planets - Institute for Astronomybarnes/ast241_f15/gp/gp1.pdf · -100 cold enough for ammonia 10 condense to form clouds _100 cold enough for ammonium hydrosulfide to condense

Astronomy 241: Foundations of Astrophysics I

21. Giant Planets

“Gas Giants” “Ice Worlds”

Two Types of Jovian Planets

12 hours on Jupiter

Surface Appearance

Surface Appearance: Cloud Colors

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ops NH3

NH4SH

H2O

Surface Appearance: Belts

Convection and rapid rotation organize atmospheric motion.

Belts: sinking gas exposes red NH4SH clouds; circulates faster.

Zones: rising gas forms white NH3 clouds;

circulates slower.

Jupiter Unpeeled

Surface Appearance: Circulation Patterns

Approaching Jupiter

Surface Appearance: Great Red Spot

Outward AppearanceSurface Appearance: Great Red Spot

Jupiter's Great Red Spot Region

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Surface Appearance: Saturn

Saturn … Four Years On

Bands like Jupiter’s, but less dramatic since atmosphere is deeper due to weaker gravity.

Surface Appearance: Uranus & Neptune

Their atmospheres are deep, methane-rich, and very cold.

• Cloud layers are too deep to be easily seen.

• Methane (CH4) absorbs red light, transmits blue.

— blue planets with subtle cloud features.

Surface Appearance: Uranus & Neptune

Great Dark Spot