15.Planetary Interiors

7/23/2019 15.Planetary Interiors

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Interiors of Worlds and

Heat loss



Differentiation -materials

separate into layers by gravity



How do we learn about

planetary interiors?•Measure moment of inertia & average density

• Observe seismic events

• Study planetary magnetic fields



ves travel in straight lines unless diverted by the

material they travel through.

1. refract due to densitychanges.

1. refract due tocomposition changes

1. reflect dues to

boundary changes



What does a Planetary Magnetic

Field look like?



Interiors and Magnetic FieldsWe can deduce that any world with a global

magnetic field has 2 things:

• It has an electricallyconducting materialwithin it.

• The material is amoving, circulatingliquid.

(movement usuallycaused by the rapidrotation of a planet)



Interiors and Magnetic Fields

• It has an electricallyconducting materialwithin it.

• The material is a moving,circulating liquid.

• It has two internal layerscomposed of a solid layerinside a liquid one.

Terrestrial Worlds like Earth have a 3rd



Interior of our planetgaseous atmosphere

(lowest density)



Interior of Terrestrial Worlds



Interiors: Gas Giant v.s Terrestrial



The magnetic

fields of gasgiants indicate

that there are

large amounts

of circulating,electrically-

conducting

materials.

Metallic hydrogen

or water

Interior of Gas Giant Worlds



© 2014 Pearson Education, Inc.

Which of the following layers of a

planet is not characterized by its

density?

A.core

B.mantleC.lithosphere

D.crust

E.none of the above




Which of the following layers of a

planet is not characterized by its

density?

A.core

B.mantleC.lithosphere

D.crust

E.none of the above



Heat loss



Planets gaintheir initial

internal heat

energy whenthey first form

Pl t d th t f th i li



Planet spend the rest of their lives

losing internal energy to space

3 T f H t l



3 Types of Heat loss• Conduction -atoms vibrate strongly causing

atoms next them to pick up energy

• Convection- heat causes fluids to move, the

hot fluid rises, the cold fluid sinks.

• Radiation- photons of electromagnetic light

carry energy away from the object



Which Forms of Heat Loss

Work Where?• All worlds conduct inside.

• All worlds radiate out to space (the only heattransfer that works in a vacuum!).

• Larger worlds convect inside.

• Largest worlds convect and radiate inside.

(wavelength of radiation depends on world mass)





Solid Convection Causing Volcanism

S lid ti i



Solid convection causing

movement, but no crustal break-up

S lid ti i



Solid convection causing

crustal break-up (Earth only)




How does an object's rate of cooling

vary with size?

A. A larger object cools more slowly than asmaller object.

B. A smaller object cools more slowly than alarger object.

C. Size has no effect on an object's rate ofcooling.

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15.Planetary Interiors