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ESCI 110: Planetary Surfaces
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Exercise 3
Surfaces of the Planets and Moons
Introduction
Our knowledge of the solar system has exploded with the space exploration programs of the
last 40 years. This new knowledge has led to two major conclusions: 1) impacts of objects crashing
into planetary and lunar surfaces was very important in modifying these surfaces, especially early in
the history of the solar system, and 2) the earth is unique within the solar system compared to the other
planets and moons.
In this exercise we will look at planetary surfaces and introduce the general categories of
materials they are made of and the processes that modify them.
Objectives
Upon completion of this exercise, you should be able to:
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
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
List the types of materials that make up planetary surfaces
Provide examples of planets or moons with surfaces dominated by gasses, ice, rocks or liquid
water
List the basic types of processes that modify planetary surfaces
Identify the effects of different processes in modifying planetary surfaces
Determine the relative age of different surfaces on the same moon or planet
Background Information
In a very general way, the composition of the surfaces of the moons and planets can be divided
into four major categories:

Gas giants. The Jovian planets apparently have no solid surface as we would be familiar with
it. Instead, they are composed of giant balls of gas, with the gasses becoming denser with
depth until they gradually turn into liquid. The outer surfaces of these planets are therefore in
constant motion.

Ice surfaces. These surfaces are dominated by frozen liquids that have relatively low melting
points. Any process that generates enough heat will therefore melt the surface, smoothing it
out.

Rocky surfaces. These surfaces are dominated by solid materials that have relatively high
melting points, and are capable of maintaining substantial relief over time.
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Liquid surfaces. Significant portions of the planet are covered with liquid.
The processes which modify planetary surfaces can be divided into the following categories:
ESCI 110: Planetary Surfaces
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 Impacts. Objects that strike the surface of a moon or planet are typically traveling at tens of
thousands of kilometers an hour relative to the target. On a solid surface the collision will
leave an impact crater. A relatively fresh impact crater may send rays of ejecta across the
land, and large craters will generally have a raised area in the center caused by the rebound
of rocks compressed directly under the impact site.
 Volcanoes. Volcanoes are mountainous landforms that build up where liquid rock material
escapes from the surface of the planet or moon. In many cases lava flows may be found
extending from the central vent of the volcano.
 Tectonics. Forces within the moon or planet may put stress on the surface, and modify it in
the form of faults or folds.
 Surface processes. If the moon or planet has an ocean or atmosphere, the surface may be
significantly modified by the influence of wind, running water, ice, waves or gravity.
One very important consideration in studying the history of a planetary surface is to determine
the age of the surface under study. Impacts occurred at the greatest rate early in the history of the solar
system, and impact craters also accumulate over time. Therefore older surfaces will have a higher
density of impact craters than younger surfaces.
We can also use the principle of crosscutting relationships to determine the relative age of
adjacent surfaces. If a fault cuts through an impact crater, for example, we know that the crater had to
be there before the fault began to move.
Pre lab Exercise
Use the words below correctly in a sentence
Lunar Highlands ____________________________________________________________________
______________________________________________________________________
Maria __________________________________________________________________
______________________________________________________________________
Meteorite _______________________________________________________________
______________________________________________________________________
Answer question 5, from 650. __________________________________________________
______________________________________________________________________
ESCI 110: Planetary Surfaces
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Lab Exercises
Questions (If any of the images are unclear ask your instructor to display them up on the screen so you
may observe a clear photograph)
1. The image to the right shows part of the
surface of the moon. The lighter area on the left is
part of the lunar highlands, while the dark region on
the right is part of one of the maria. Which process
from the list above dominates the surface of the
highlands?
__________________________
Which surface is older, the highlands or the
maria, and how can you tell from this photo?
__________________________________________
__________________________________________
__________________________________________
2. The image to the right shows part of the
surface of Mercury. Is this surface
gaseous, icy, rocky or liquid?
___________________
From what you see in the image, is
the surface of Mercury closer in age to the
highlands of the Moon or the lunar maria?
Explain the reason for your answer.
__________________________________
__________________________________
__________________________________
3. This image shows part of the surface of Jupiter.
What type of material is Jupiter made of, and what is your
evidence?
_____________________________________________
Jupiter was recently struck by several pieces of a large
comet. Circle the evidence of impact you see on this image,
and describe what has happened to these impact structures
since they formed:
ESCI 110: Planetary Surfaces
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____________________________________________________________________________
_____________________________________________________________________________
4. The image to the right is a radar image that
shows the solid surface of part of Venus beneath the
clouds. The surface of Venus is clearly composed of rocky
material and volcanoes that are at least somewhat similar to
that found on parts of the earth. What process is
responsible for this part of the landscape on Venus?
_____________________________________________
How old is the surface of this part of Venus
compared to the surface of the Moon?
__________________________________________
ESCI 110: Planetary Surfaces
Jupiter’s moon Io
Close up of Surface of Ganymede
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Surface of Ganymede
Surface of Europa
5. These four images show surfaces of three of the moons of Jupiter. What type of material is
the surface of Europa composed of? _______________________________________
What process dominates the surface of Io? ___________________________________________
What evidence do you see for tectonic activity on Ganymede? ___________________________
Which part of which moon appears to be the oldest in age, and what evidence supports that conclusion
from the images provided? _____________________________________________
____________________________________________________________________________
ESCI 110: Planetary Surfaces
Olympus Mons
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Dune Field
Ophir Chasma
6. The three images above show different parts of the surface of Mars at three completely
different scales (Olympus Mons is the size of Ohio, Ophir Chasma is as deep as the Grand Canyon,
and the dune field is show at a high magnification).
Overall, is the surface of Mars relatively young or very old? ____________
Which two processes dominated the surfaces in these regions? ____________________
7. Earth. This photo has
converted to a grayscale image
a color photo taken by the Apollo
astronauts. Saudi Arabia is in the
middle of the picture.
What two types of
materials dominate the visible
surface of the earth?
________________________________
What evidence do you see for tectonic activity in this image? ______________________
Is the surface of the earth relatively young or relatively old compared to other planetary
surfaces, and how can you tell?
_____________________________________________________
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