Planetary Geology

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Planetary Geology
Mercury Venus Earth Moon Mars

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Planet layers

• There are _____ ways to classify a planets
  layers
• By ____________________
• By ____________________
• _______________________
• Whats a _____________?
• Heres what we find for Earth
• _____________________________________

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Chemical layers in Terrestrial Planets
Which layer is densest?
Least dense?
The separation into different density layers is
called _____________
What had to happen in order for the planet to
____________________? (Demo!) (pp __________)
Which cools off faster meatball or baked
potatoes? Which cools faster Earth or Mercury?
Which is the hottest layer? Why?
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Solids vs. fluids
________________
___________________________ ______________________
_____) comes from the bottom of the ___________,
where _________.
__________________________ _______________________
__ _________________________
_________________ ______________
_________________________ ________________________
_ _________________________ Which _______ is
hotter? Which is solid? Why?
Why is most of the mantle still a fluid? Why
________________?
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Determining compositions
Which of the 4 different regions of the planet is
easiest to determine its composition?
Why? __________ determine composition of
________, which comes from the _________________.
Core __________ studying ______________ to map
_____________________. We assume _______________
_____________________. See pp ____________
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Comparing the layers

• Look at figure 9.2
• What trend do you see about core size? Which
  worlds are exceptions? How do we explain that?
• What do you see about lithosphere thickness?
• Recall lithosphere boundary where rocks melt.
• Whats the temperature at the boundary?
• Which planets will cool off first?
• Which planets should have the thickest
  lithosphere?
• Should smaller worlds have active volcanoes?

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Interior Planet Heating (pp. ________)

• _________________ (local heating only)
• _____________________ energy
• __________________
• __________________
• ______________________
• See also figure 9.4
• Clicker questions

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Can the Terrestrial planets harvest gravitational
energy by contracting, today?

1. Yes
2. No

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Can the Terrestrial planets harvest gravitational
energy by differentiating, today?

1. Yes
2. No

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Radioactive decay releases more energy

1. In the early solar system
2. Currently

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Planetary Cooling (p. _____)

• Primary method of surface cooling is
• ___________________________
• Which kind __________________?
• Interiors also cool by
• _____________________________
• ______________________________
• _________________________ towards surface
• ______________________________________
• ________________________________
• See also figure 9.5
• Show the Tectonic Activity Heat Transfer
  animation

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Making Magnetic Fields
See pages _________
Magnets produce magnetic fields
So do _______________.

• Planets can too, if ____________ meets 3
  conditions

How many of these does Venus have? Should it have
a strong magnetic field? How about Mars? The Moon?
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Based on what you know, should Mercury have a
magnetic field?

1. Yes
2. No

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Based on what you know, should Jovian planets
have a magnetic field?

1. Yes
2. No

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Earths Magnetic Field
See pages _________
Protects us from ____________ such as ___________
We dont understand Earths mag. field well. It
flips every ________________ yrs or so. Nobody
knows why. Numbers arent even known precisely!
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______!
________ are caused when ____________
_________________ trapped in our
_________________ hit the ___________
________________, _________________! Green comes
from _________________!
Why are they called Northern lights
(_______________) or Southern lights
(__________________?) Why mostly at the
____________?
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Surface Processes
Four processes that alter the appearance of
planetary surfaces

1. __________________ (figure 9.1, 9.8, 9.9)
2. __________________
3. __________________________
4. ____________________________

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Surface features

• Study figure 9.15
• It puts all of the pieces together from the
  previous several mini-units.
• It also covers atmospheres well do more of that
  later.

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Review Simplified History
_________________________________
Recall 1 Gyr ___________________
This history was determined by ___________________
__ ________________________!
How old are the planets in the solar
system? Note the Sun is ________ years old. Its
______ burned out. How much longer will it last?
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Crater Formation
Before
______________! Why is 11 km/sec minimum?
Rocky or icy objects (also called ___ ___ )
This is going to leave a mark
Impact sites ground gets vaporized. So does the
impactor!
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Craters
An object this size
Will make a crater this big!
Diameter of crater is about ______diameter of
rock. Depth of crater is about _________the
diameter of rock. See also p. ____
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Crater _____
These streaks of ejecta are called _____.
________________________________ over about
_____________ years because _____________________
chemically alters them.
Most prominent under _______________ (at what
time, locally?).
rays
So, how can you find the youngest craters on the
Moon?
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Crater Sizes
Small lt 25 km
Big - up to 200 km
Note the central peaks
This puppy is the size of the L.A. basin!
And
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REALLY HUGE!!
Also known as multi-ring impact basins
Similar, but a bit larger crater formed on
Mercury, and on the opposite side, we see weird
terrain see page ____.
That just had to hurt.
Big crater on the Moon
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How do we measure ages?

• Relative dating Principle of Superposition
  Ordering of events based on appearance.
• Crater counts surfaces with _______________ are
  new or old? Why? (see p. ____________)
• Radiometric dating of rocks. (see also section
  8.5) Called Carbon dating when used on recent
  fossils.

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Relative Surface Dating Can you order the
events?
A. Volcanic Eruption
B. Fault
C. Crater
D. Hills

• Cratered Terrain
• (Hint old or new?
• Created when?)

G. Crater
F. Crater
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A Real Example - Iapetus
What can you say about the age of the small
crater? Landslide?
Smaller Crater
Crater Rim
Iapetus is one of Saturns moons. Picture taken
by Cassini
Scarp (Shrinkage quake) subsequent landslide
There is cratering on ground. Do you see many or
few craters in this big crater? What does that
tell you about the circled crater? Is old or new?
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Iapetus entire moon

• Diameter 1460 km
• Heres the big crater we just looked at.
• Approx 500 km across
• Landslide is here.
• Ridge all along equator. Mystery!

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Summary review material

• Where is the densest part of a planet located?
• What are the four layers of a terrestrial planet
  called? What are they made of?
• Where is the hottest part of a planet, and why?
• What size and depth a crater will a 1 km asteroid
  make if it hits a planet?
• What do the youngest craters look like?
• How do you determine the history of a planet?
• What causes magnetic fields around planets.