interiors of worlds and heat loss. differentiation -materials separate into layers by gravity
TRANSCRIPT
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
Interior of our planetgaseous atmosphere
(lowest density)
Interior of Terrestrial Worlds
Interiors: Gas Giant v.s Terrestrial
The magnetic fields of gas giants indicate that there are large amounts of circulating, electrically-conducting materials.
Metallic hydrogen or water
Interior of Gas Giant Worlds
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Which of the following layers of a planet is not characterized by its
density?
A.core
B.mantle
C.lithosphere
D.crust
E.none of the above
Heat loss
Planets gain their initial internal heat energy when they first form
Planet spend the rest of their lives losing internal energy to space
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 heat transfer 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
Solid convection causing movement, but no crustal break-up
Solid convection causing crustal break-up (Earth only)
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How does an object's rate of cooling vary with size?
A. A larger object cools more slowly than a smaller object.
B. A smaller object cools more slowly than a larger object.
C. Size has no effect on an object's rate of cooling.
Geologic Processes
Geological Processes• Tectonics
– Rocks bend and break (folding and faulting).
• Volcanism– Materials melt, explode and freeze.
• Erosion and surface processes– Surfaces flatten out: mountains crumble and holes
are filled in. Mass wasting (gravity action) Wind action Water action
• Impact Cratering (external)– Bodies from space hit the ground, making a hole.
Tectonics -Folding• When rocks are squashed they will compress
and bend away from the direction of maximum pressure
Tectonics -Faulting1. Extension Faults -crust moves apart, makes a larger area.
1. Compression Faults -crust moves together, makes smaller area.
1. Strike-slip Faults
-crust moves sideways,
no gain or loss of area
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What is true of convection that stresses a planet's crust?
A. Mountains may form where the crust is pushed together.
B. Cracks and valleys may form where the crust is pulled apart.
C. Convection has no effect on a planet's crust.
D. A and B
Volcanism
• Materials melt, erupt and explode, then freeze and coat the surface
Generic Volcano Structure
Volcanic Processes• Rocks melt and explode.• 2 components: lava, gasses• Lavas - variable viscosity,depending on chemistry
• Low viscosity range of viscosity High viscosity (runny lava) (gooey, sticky lava)
Low gas content High gas Result: Result: Low broad shapes range of volcanoes Tall cone
shapes Volcanic Shield Cinder Stratovolcanoes
Floods Volcanoes cones
Volcanic Floods -VERY low Viscosity
Hawaiian Effusive eruption
Olympus Mons Martian Shield Volcano
• Note the broad shield shape and the central cauldera
Volcanic Processes• Rocks melt and explode.• 2 components: lava, gasses• Lavas - variable viscosity,depending on chemistry
• Low viscosity range of viscosity High viscosity (runny lava) (gooey, sticky lava)
Low gas content High gas Result: Result: Low broad shapes range of volcanoes Tall cone
shapes Volcanic Shield Cinder Stratovolcanoes
Floods Volcanoes cones
Explosive Stratovolcanos
• Occur only on Eartha product of plate tectonics
Alternative Materials
sulfur volcanoes, Io
carbonatites, East Africa, Earth
Water eruption plume, Enceladus
Erosion and Surface Processes Gravity pulls everything into a smooth sphere. Thus,
surfaces flatten out: mountains crumble and holes are filled in.
The processes that carry out erosion each show characteristic patterns that we can see on Earth and on different worlds:
Mass wasting (gravity action)- land slides
Wind action- sand dunes, wind streaks
Water action- river channels, ocean shores, glacial erosion
Sand Dunes in the Sahara (imaged by the Space Shuttle)
Ice/tar dunes on Titan
Water Channels on Mars
Ethane Channels on Titan
Impact Cratering• Bodies from space hit the ground, making a hole.
(the only external process -it comes to the planet from the outside)
• The size of the hole depends on the energy of the impact. – A small, slow-moving, ice-ball makes a small hole.– A massive, fast moving, rock makes a large hole.
Imbrium BasinMoon
Crater Dating• Solar System debris falls onto planets at a regular
rate, making craters.
• The number of holes on a surface is a measure of how long it has been exposed to impacts.
• Impact craters can be destroyed by the three internal processes (tectonics, volcanism, erosion)
• Surfaces with few craters have active processes destroying the craters. (called YOUNG surfaces)
• Surfaces with lots of craters have no active processes & are undisturbed. (OLD surfaces)
Which Surface is Older?
A
B
Which World is More Active?(Be able to explain your choice)
Earth Moon
Planetary Atmospheres
Atmospheric Basics
• Our goals for learning• What is an atmosphere?
• How do you obtain an atmosphere?
What is an atmosphere?
An atmosphere is a layer of gas that surrounds a world
How do you obtain an atmosphere?
– Gain volatiles by comet impacts
– outgassing during differentiation
– Ongoing outgassing by volcanoes
Keeping an Atmosphere
• Atmosphere is kept by the world’s gravity and temperatures– Low mass (small) worlds = low gravity = little atm.
– High mass(large) worlds = high gravity = thick atm.
– Low temperatures = slow gases = more atm.
– High temperatures =excited gases = atm.loss
• Gravity and pressure– Air pressure depends on how much weight of
gas is there ie. The atmospheric thickness.
What have we learned?
• What is an atmosphere?– A layer of gas that surrounds a world
• How do you obtain an atmosphere?– comet impacts plus outgassing by differentiation,
or volcanoes.– How much atmosphere is retained depends on
the world’s gravity and temperatures
Atmospheric Processes 1
• Our goals for learning
• What are the key processes?
• What creates wind and weather?
• How does the greenhouse effect warm a planet?
Atmospheric Processes
• Atmospheric circulation (convection)– Convection cells move gas from equator to pole and
back.
• Coriolis Effect– Gas dragged sideways by the rotation rate of the
world.
• Greenhouse Effect– Infrared energy is re-reflected back to the ground by
CO2
Air MovementGas molecules move from high density to lower density
Atmospheric Pressure
Gas pressure depends on both density and temperature.
Adding air molecules increases the pressure in a balloon.
Heating the air also increases the pressure.(molecules more energetic)
Atmospheric Circulation (convection)
• Heated air rises at equator
• Cooler air descends at poles
Maximum Sun warming
Coriolis Effect
Coriolis Effect breaks upGlobal Circulation
• On Earth the large circulation cell breaks up into 3 smaller ones, moving diagonally
• Other worlds have more or fewer circulation cells depending on their rotation rate
Coriolis Effect
Winds blow N or S Winds blow W or EWinds are diagonal
Venus EarthMars
Jupiter, Saturn Neptune, Uranus(?)
Greenhouse Effect
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If there was no greenhouse effect, Earth...
A. would be warmer than it is today.
B. would have a thicker atmosphere.
C. would be colder than freezing.
D. would have no protection from ultraviolet radiation.
What have we learned?
• What creates wind and weather?– Atmospheric heating and Coriolis effect.
– Solar warming creates convection cells.– The coriolis effect drags winds sideways and breaks up
the cells– The faster a planet spins, the more E-W gas movement
there is
• How does the greenhouse effect warm a planet?– Atmospheric molecules allow visible sunlight to warm a
planet’s surface but absorb infrared photons, trapping the heat.