The purpose of this lab is to explore basic properties of the Jovian.docx

The purpose of this lab is to explore basic properties of the
Jovian planets and to examine geologic processes on some of
the larger moons of the outer solar system.
Part 1: A Comparison of Planetary Sizes
Background
As we saw last week, a basic property of planets is their size.
To compare sizes, we can compare the diameter (distance from
one side to the other) of one planet to another, or we can
compare the radius (half the diameter) of one planet to another.
Graphing All the Major Planets
Table 1. The average diameters* of the planets in our solar
system in kilometers (km)
MercuryVenusEarthMarsJupiterSaturnUranusNeptune487912,10
412,7426779139,822116,46450,72449,244
*Data source:
AstronomyNotes.com
Size comparison is better shown graphically than with numbers.
You have already done this for the terrestrial planets in last
week's lab.
The image above shows an example of what you will be doing.
Remember scientific notation. The numbers on the axes are 0;
20,000; 40,000; and 60,000; and refer to kilometers. In order to
plot a circle representing a planet with a 70,000 km diameter, I

first took the radius (35,000 which is half the diameter), moved
along the x-axis to 35,000, and drew a line up from zero that
was 70,000 units long. Then I repeated this for the y-axis and
sketched in the circle around the “+” that I’d drawn. Detail
about drawing the circles were shown in the video last week.
Table 1 gives the average diameters for the planets in our solar
system in kilometers. Use this data to plot circles representing
the different planets to their correct sizes on the graph paper
provided (
.png version
;
.docx version
; and
.pdf version
). Use a different color for each circle. Clearly identify which
circle corresponds to which planet (labels or keys to colors).
When you have finished, upload your completed graph to the
correct assignment box.
Figure 1. Example of graph paper used for plotting planet sizes.
Links to downloadable
.png
,
.docx
, and
.pdf
versions.
UPLOAD TO
ASSIGNMENT BOX
FOR LAB 5 - Solar-System-Planet-Sizes

Upload your diagram to the Assignment Box—name your files:
[Yourlastname]_Solar_System_Planet_Sizes
In addition to looking at a graphical representation, we
sometimes compare objects by saying how many times larger or
smaller one is relative to the other. For example: If one
student is 5.5 feet tall, and another is 6 feet tall, then we can
say that the taller student is 1.1 times taller than the shorter
student or that the shorter student is 0.92 times shorter than the
taller student. This is done by simply dividing one number into
another.
Lab 5: Question 1
Jupiter and Saturn are similar in size, but Jupiter is the largest
planet in the solar system. Jupiter is _________ times larger
than Saturn. Enter a number only. Use two significant figure
[example, 2.2 or 22]
Lab 5: Question 2
SHORT ESSAY: Spend a bit of time looking at the graph you've
created. Describe the variation that you see for the sizes of
these planets. This should be at least a paragraph, not just a
sentence or two, and should be more detailed than "some are
bigger and some are smaller". This is worth 5 points (regular
questions are worth 1 point).
Part 2: A Comparison of Planetary Masses
Mass of Jupiter

Background
We determine the mass of a planet by seeing its gravitational
pull on another object. As mentioned in
Lecture 2.4
, Galileo was the first to observe the four largest moons of
Jupiter orbiting the planet; these moons (Io, Europa, Ganymede,
and Callisto) are called the Galilean satellites after their
discoverer. These moons orbit because of Jupiter's gravitational
pull on them. Kepler noticed that planets orbiting the Sun
obeyed a relationship (his third law):
a3 =p2{"version":"1.1","math":"a3 =p2"} EQUATION 1
where
a
is the semi-major axis of the planet's orbit in astronomical
units, and
p
is the orbital period in years. For the Earth, both numbers are 1
(we're 1 A.U. from the Sun and we orbit the Sun in one year).
Newton added gravity to Kepler's third law to create an
expression that can be used for any object orbiting any other
object:
a3 =
p2×(G×M4×π2){"version":"1.1","math":"a3 = p2×G×M4×π2"}
EQUATION 2
where
a
and
p
are the same as in Equation 1,

G
is a gravitation constant (a constant number), and
M
is the mass of the central object (the Sun's mass for planets;
Jupiter for the Galilean satellites). For the Earth's orbit around
the Sun,
a
is 1 AU,
p
is 1 year,
M
is the mass of the Sun, and the value for
G
was chosen to make the term in the parentheses reduce to 1, so
that Equation 2 becomes Kepler's third law.
We can rearrange terms to solve for mass:
M =
a3p2×(4×π2G){"version":"1.1","math":"M = a3p2×4×π2G"}
EQUATION 3
We can use Equation 3 to calculate the mass of Jupiter by
watching one of its moon's orbit around it. However,
astronomical units and years are not useful for satellites that are
closer to Jupiter than Earth's Moon is to us, and that orbit
Jupiter in days, not years. So we can do conversions to adjust G
to units of Jupiter diameters (a length) and days. Doing so and
multiplying by 4 and PI squared gives us
M =
(2.27×1026)×(D3T2){"version":"1.1","math":"M = 2.27×1026×
D3T2"} EQUATION 4
where
D

is the distance between Jupiter and one of its moons in units of
Jupiter diameters, and
T
is time in days.
Measurements and Calculations
Figure 2 shows a sequence of 5 images of Jupiter and its four
largest satellites, taken on different nights at different times.
We are going to use the motion of Callisto (the
outermost
moon) around Jupiter to determine the mass of Jupiter, using
Equation 4.
You will be making your measurements on a much larger
version of this image. [
Link to larger version of Figure 2
]. You should be able to magnify this; you can also download
and open with a photo viewer or paint program and magnify.
Figure 2. Small version of screen shots showing the 4 Galilean
satellites orbiting Jupiter. Original source (
Penn State
) has replaced simulator with a very different one since these
screen captures were made.
In order to use Equation 4, you need to determine
D
(the distance between Callisto and Jupiter in Jupiter Diameters-
JD), and
T
(the time in days). The figure below is an enlargement of the
first (September 3) image in Figure 2. I've measured the
distance between the surface of Jupiter and the surface of
Callisto as 13.8 JD, using a screen shot and small circles that

are approximately the same size as Jupiter. I measured this
with a millimeter ruler and got 13.6 JD. Another instructor
measured this distance and got 13.1 JD. So this number will
vary depending on the accuracy of your measurement.
Figure 3. Enlargement of the left hand side of the September
3rd image from Figure 2. We measure JD (Jupiter Diameters)
from the surface of Jupiter to the surface of Callisto. There are
13 full JD and an additional partial JD between the two objects.
Determine the distance
[
] For each of the five observations (use the large version of
Figure 2), determine Callisto's orbital distance in JD.
Write down your individual measurements for Callisto's orbital
distance. You will use the average of these values in
subsequent calculations
September 3: ____________ JD (Jupiter Diameters)
September 12: ___________ JD (Jupiter Diameters)
October 7: ______________ JD (Jupiter Diameters)
Lab 5: Question 3

Average the 5 measurements you made and enter that average in
the box provided. Important: Use only 3 significant digits (so
13.8 rather than 13.833333). [Hint: your average should be
between 13.0 and 14.0).
• Average of 5 values: ___________ JD (Jupiter Diameters)
Determine the Time
The date and time for each image is given on the left hand side.
Times are U.T. or universal time (so 21:00 UT is 9 pm in
Greenwich England). The date is also given in Julian Days,
which is used mainly by astronomers, assuming that the zero
point is at noon U.T. on January 1, 4713 BC (or BCE). You can
subtract the two numbers to get the difference in time (in UT).
This has been done for you.
Time from September 3 to September 12 observations: 8.5 days
Time from September 12 to September 20 observations: 8.1
days
Time from September 20 to September 28 observations: 8.2days
Time from September 28 to October 7 observations: 8.4 days
Lab 5: Question 4
What is the average length of time between the images? Enter a
number in the box provided. Use only 2 significant digits (such

as 8.1).
But, for Equation 4, we want the time for a complete orbit by
Callisto. Each image was taken at approximately half the
orbital period, so Callisto is on the left, then the right, then the
left, and so on. You need to double the answer to Question 4 to
get the orbital period in days.
Lab 5: Question 5
What is the orbital period for Callisto in days. You need to
double your answer to Question 4. Enter an answer with three
significant figures (put only one digit after the decimal point).
Now use Equation 4 and your answers to Question 3 (use the
average) and Question 5 to calculate the mass of Jupiter. Your
answer will not exactly match the true value. I came out
slightly high and another instructor came out slightly low.
Lab 5: Question 6
This is a short answer essay question, and is worth 5 points. In
the box provided, include
• your calculated mass of Jupiter (answer is in kilograms)
• your calculations (how you used Equation 4 to get your
answer)
• a short discussion comparing your answer to the published
value (given in Table 2 below).
Planets and Solar System

What exactly is mass? Chemists will often define mass as the
amount of matter in an object (matter is something that will
have weight in a gravitational field), while physicists often talk
about something with more mass having more inertia than
something will less mass. Geologists and planetary scientists
tend to think more about density than mass (as we learned in
module 3, density is the amount of mass in a given volume).
ρ=MV{"version":"1.1","math":"ρ=MV"} EQUATION 5
where
ρ
is density,
M
is mass, and
V
is volume. Planets and stars are spherical (more or less), which
means their volumes can be approximated by
Vsphere=43×π×r3{"version":"1.1","math":"Vsphere=43×π×r3"}
EQUATION 6
where
r
is the radius of the sphere.
So, comparing sizes and masses can give us some information
about the density (and therefore composition) of an object. For
example, the Earth and the Moon are both terrestrial worlds
containing rock and metal. The Earth's diameter (twice the
radius is 12,742 km, as shown in Table 1 above. The Moon's
diameter is 3,476 km (
NASA
). We can say that the Earth is 3.67 times larger than the Moon
(12,742 divided by 3,476), or between 3 and 4 times larger.

The masses for the Earth and Moon are given in Table 2. If the
Earth and Moon were made of exactly the same material, we'd
expect the Earth to be about 50 times more massive than the
Moon (
all the terms in equations 5 and 6 drop out except for the two
masses and the two radii cubed, so 3.67 cubed, i.e., relative
sizes cubed
). If we look at the masses of the Earth and Moon (Table 2), we
can see that the Earth is actually almost 82 times more massive
than the Moon, which clearly indicates that the material making
up the Earth has an average density greater than the material
making up the Moon.
So let's compare the two largest Jovian planets. Jupiter and
Saturn are fairly similar in size (you calculated this is Question
1).
Lab 5: Question 7
Assuming that Jupiter and Saturn are the same density, then
how many times more massive do you expect Jupiter to be
relative to Saturn (use your answer to Question 1 for the
relative sizes)? Enter only a number.
Lab 5: Question 8
Using the values in Table 2, how many times more massive is
Jupiter than Saturn in reality? Enter only a number.
Despite being composed of roughly the same materials, Jupiter
and Saturn are not the same density. This is because gas will
compress more in a stronger gravitational field.
Table 2. Masses for solar system objects

Planet/
Object
Mass
(times 1024 kg)
Object
Mass
(times 1024 kg)
Mercury
0.330
Sun
1,988,500
Venus
4.87
Earth's Moon
0.073
Earth
5.97

All Asteroids
0.00239
Mars
0.642
All Jupiter's Moons
0.39312
Jupiter
1898
All Saturn's Moons
0.1406
Saturn
568
All Uranus' Moons
0.008876
Uranus
86.8
All Neptune's Moons
0.021492

Neptune
102
Charon
0.001586
Pluto
0.0146
Kuiper Belt
0.13552
References for Table 2:
Planets, Earth's Moon
, Pluto
;
Sun
;
Asteroids
;
Jupiter's Moons
;
Saturn's Moons
;
Uranus' Moons
;
Neptune's Moons
;
Charon
;
Kuiper Belt
. (All are NASA fact sheets, except for Asteroid Belt and

Kuiper Belt which are based on recent research papers.)
Jupiter has often been called a "failed star" because it is very
similar in composition to the Sun, but much less massive. Table
2 gives the masses for everything in the solar system (at least
for everything that currently has measured or estimated masses).
Lab 5: Question 9
How many times more massive is the Sun than Jupiter?
We can also think about the mass of the Sun (or Jupiter) as a
percentage of the total mass. For example, if I have 5 marbles
that are all identical, one marble will have 1/5th of the mass of
the entire group of marbles, which is 20% of the total mass.
You calculate this by taking 1 marble, dividing it by all of the
marbles (1/5 = 0.2) and then multiplying by 100 to get percent.
The Sun makes up approximately 99.86% of the total mass of
the solar system. So the rest of the solar system is insignificant
in terms of mass. The Jovian planets make up most of that
remaining mass.
Lab 5: Question 10
Jupiter's mass makes up what percentage of the mass of the
solar system that is NOT in the Sun (exclude the Sun)? Enter
only a number.
Part 2: Satellites of the Jovian Planets
Background
The larger moons of the outer planets are large enough to be
considered planets if they orbited the Sun directly, instead of

orbiting a planet. Both Ganymede and Titan are actually larger
than Mercury (the innermost planet in our solar system).
Callisto is only slightly smaller than Mercury. Io, Europa, and
Triton are similar in size to Earth's Moon.
Figure 4. Selected moons of the outer solar system, with the
Earth and Earth's moon for scale. Credit: OpenStax Astronomy.
Jupiter's Moon: Io
Io, the innermost of the four large moons of Jupiter is the only
large satellite in the outer solar system that does not have an icy
surface. This is because it is the most volcanically active moon
in the solar system, and the surface is constantly being covered
with newly erupted material (rock and sulfur deposits).
The figure below shows lava flows associated with the Amirani
hotspot volcano and associated plume (this image has been
color-enhanced.) Image data are shown for two flybys of Io by
the Galileo spacecraft, from orbit I24 (Oct. 11, 1999; Day of
Year = 284) and from orbit I27 (Feb. 22, 2000; Day of Year =
53). The left color panel shows lava flows (black & dark
brown), SO2-condensate deposits (white-pink) from the Amirani
plume, and S-rich deposits (yellow, red-brown). The rightmost
panel shows areas of new lava in two inset regions (region 1
top, region 2 bottom row). This new lava (which is colored in
red on the rightmost set of images) was erupted sometime
between the two observation dates.
Figure 5. Original caption (parts omitted): "These images from
NASA's Galileo spacecraft show changes in the largest active
field lava flows in the solar system, the Amirani lava flow on
Jupiter's moon Io. Scientists have identified 23 distinct new
flows by comparing the two images taken 134 days apart, on

Oct. 11, 1999, and Feb. 22, 2000. The color image on the left is
a composite of black-and-white images collected on Feb. 22,
2000 and June 30, 1999. The white boxes and arrows show the
locations of the areas analyzed in detail on the right. The left-
hand pair of black-and-white images, labeled I24, are parts of a
mosaic collected on Oct. 11, 1999. The center pair of images,
labeled I27, shows what the same areas looked like on Feb. 22,
2000. These later images are about twice as sharp as the earlier
images, making some features that did not change appear
crisper. In order to demonstrate the real changes, the I27 images
were divided by the I24 images, producing the pair of ratio
images on the right. The new dark lava that erupted between
October 1999 and February 2000 has been highlighted in red."
Image and caption from
NASA
(PIA02585).
If we assume that this rate of eruption is typical, we can
calculate how long it would take to resurface Io (cover the
entire moon with a new surface of recent lava flows).
The first step is to determine the rate of resurfacing. We can
use the information for the Amirani region by looking at the
amount of surface area covered between the two observations
divided by the time between the two observations.
The area of new lava in Regions 1 and 2 of Amirani has been
estimated from the red-colored images as:
Area of new flows in Region 1 - 285 km2.
Area of new flows in Region 2 - 340 km2.

Lab 5: Question 11
What is the average amount of new lava produced between the
two observations (the average area)? Enter a number in the box
provided.
The two images were taken 135 days apart (October 11, 1999 to
February 22, 2000). We're going to want to use years rather
than days for our units, so we divide 135 by 365.25 to get 0.37
years between the two images.
In order to calculate the time needed to resurface Io, you need
to know the resurfacing rate for the Amirani region. In order to
ensure that you know this, enter your answer for the resurfacing
rate into Mini Quiz 1, and check the feedback for the correct
answer before continuing with the main lab quiz.
Mini Quiz 1
Calculate the rate of resurfacing by lava in km2/year for the
Amirani region using your answer to Question 11 and the time
between the two image. Average resurfacing rate near Amirani
hotspot is ________ km2/year.
Enter your answer (a single number) in the box provided.
When you are done, please check the Mini Quiz 1 feedback.
Subsequent questions
depend on using the number given in the feedback,
regardless of whether your answer was marked correct or not.

Use this number, and not your answer
for the calculations that follow.
Please make sure you have the correct answer (given under
"View Feedback"
after you submit your quiz--click on the link to show the
feedback). Use the correct value in order to answer Question 12
below.
Assuming that the resurfacing rate for the Amirani region is
representative for Io as a whole, we can use the answer to Mini
Quiz 1 to calculate the time needed to resurface all of Io.
However, we first need to know how much area needs to be
covered. Io's surface area can be approximated by the surface
area of a sphere:
surface area of a sphere =
4×π×r2{"version":"1.1","math":"surface area of a sphere = 4×π×
r2"} EQUATION 7
where
r
is the radius of the sphere. Io's radius is 1821 km.
Mini Quiz 2
Calculate the surface area of Io in km2. The surface area of Io
is ________ km2.
Enter your answer (a single number) in the box provided. Do
not use scientific notation, and do not include any commas.

When you are done, please check the Mini Quiz 2 feedback.
Subsequent questions
depend on using the number given in the feedback,
regardless of whether your answer was marked correct or not.
Use this number, and not your answer
Please make sure you have the correct answer (given under
"View Feedback" after you submit your quiz). Use the correct
value in order to answer Question 12 below.
The time to resurface Io is equal to Io's surface area divided by
the average resurfacing rate.
Lab 5: Question 12
The time needed to resurface Io by volcanic flows is _______
years. Enter a number in the box provided.
Jupiter's Moon: Europa
"Scientists have good reason to believe that Jupiter’s moon
Europa has a liquid ocean wedged between its ice shell and a
rocky sea floor. Though it has a known radius of 1,561
kilometers -- slightly smaller than Earth’s moon --
uncertainty exists about the exact thickness of Europa’s ice
shell and the depth of its ocean."
NASA/JPL
. Estimates for Europa's ice shell range from 2 to 30 kilometers
thick, and estimates of the water layer beneath the surface range
from 3.5 to 100 kilometers thick.

Figure 6. Model showing layers inside Europa. A metallic core
(colored black) is in the center, surrounded by a thick rocky
layer (brown), with an ocean of liquid water on top of the rock
(blue), all capped by a layer of ice (white surface layer). Image
source:
NASA/JPL
.
How much water is on Europa? With the uncertainties on the
thicknesses of the icy crust and the water layer, all we can do is
estimate a maximum and minimum possible value for the
volume of the ocean. How do we do this? We determine the
volume of a spherical layer by subtracting the volume of a
smaller sphere (the bottom of the ocean) from the volume of a
larger sphere (the top of the ocean), using Equation 6 (given
earlier on this page).
Figure 7. Model for Europa's interior showing metallic core
(black), rocky mantle (brown), water layer (blue) and ice layer
(white). Lines indicate the radii for the top and bottom of the
water layer. Illustration by M. Hutson/PCC.
We need to determine the radius for the top and bottom of the
ocean layer. We know the radius of Io (1,561 km). The top of
the ocean layer will be the bottom of the outermost ice layer.
The ice layer has an estimate thickness of between 2 and 30
km.
STEP 1: Find the minimum and maximum radius of the top of
the water layer, which is Europa minus its ice shell.

Minimum rtop: 1,561 km - 30 km = 1,531 km
Maximum rtop: 1,561 km - 2 km = 1,559 km
STEP 2: Find the minimum and maximum radius of the bottom
of the water layer (which is also the top of Europa’s rocky
interior)
by subtracting the ice thickness and ocean depth from the radius
Minimum rbottom: 1,561 km - (30 km + 3.5 km) = 1,527.5 km
Maximum rbottom: 1,561 km - (2 km + 100 km) = 1,459 km
STEP 3: Use the formula for the volume of a sphere (Equation
6) to find the minimum and maximum volume for Europa’s
ocean layer.
Minimum volume of Europa's ocean: 4 x PI x(1,5313 -
1,527.53) = 102,857,290 km3
Maximum volume of Europa's ocean: 4 x PI x(1,5593 - 1,4593)
= 2,862,511,574 km3
So the range of possible values for the volume of Europa's
ocean is approximately 100 million cubic kilometers to almost
2.9 billion cubic kilometers. How much water is that? Let's
compare to some bodies of water on Earth.
Table 3: Volumes of water contained in different bodies on
Earth.

Lake Superior
Volume of water: 12,100 cubic kilometers
Data Source:
Cook County
Image Source:
Wikimedia
Mediterranean Sea
Volume of water: 3,750,000 cubic kilometers
Data Source:
Wikipedia
Image Source:
NASA
Earth's Oceans
Volume of water: approximately
1.35 billion cubic kilometers
Data Source:
Wikipedia
Image Source:
NASA

Lab 5: Question13
The minimum estimated volume of water on Europa is
__________.
• similar in size to Lake Superior
• approximately 1/3 the volume of the Mediterranean Sea
• approximately 3 times the volume of the Mediterranean Sea
• approximately 1/2 the volume of the Earth's oceans
• approximately 2 times the volume of the Earth's oceans
Lab 5: Question 14
The maximum estimated volume of water on Europa is
__________.
• approximately 1/3 the volume of the Mediterranean Sea
• approximately 1/2 the volume of the Earth's oceans

• approximately 2 times the volume of the Earth's oceans
Jupiter's Moons Compared
Figure 8. Original caption (some text removed): "This mosaic
includes images taken by NASA's Galileo spacecraft during nine
orbits around Jupiter and its four largest satellites. From left to
right, the moons shown are Io, Europa, Ganymede, and Callisto.
Most of the images were acquired between June 1996 and June
1997 by Galileo, but three images- Callisto in the top row,
Ganymede in the middle row and Io in the bottom row-are from
Voyager's mission to Jupiter in 1979. The top row displays the
relative sizes of the moons in global views at relatively low
resolution. The images, scaled to about 10 kilometers (3.9
miles) per picture element (pixel), feature the smallest visible
features of about 20 kilometers (12.4 miles). Middle row images
show regional views of up to 10 times higher resolution, each
covering an area about 1,000 by 750 kilometers (621 by 466
miles) and scaled to about 1.8 kilometer (1.1 mile) per pixel.
Bottom row views represent the highest resolutions, covering
areas about 100 by 75 kilometers (62 by 47 miles) and scaled to
about 180 meters (197 yards) per pixel. Spectral regions not
visible to the eye are shown, indicating differences in surface
chemical composition or changes in the way the surface reflects
sunlight. For example, in the left middle image, bright red
depicts newly-ejected volcanic material on Io, and the
surrounding yellow materials are older sulphur deposits. The
picture to its right shows enormous cracks in Europa's icy shell.
Blue represents ice and reddish areas probably represent a thin
coating of darker material ejected by ice volcanoes along the
cracks." Source:
NASA Photojournal
(PIA00743).

Lab 5: Question15
Put the four Galilean moons in order of distance from Jupiter
(from closest to Jupiter to farthest from Jupiter).
• Callisto
• Europa
• Io
• Ganymede
Lab 5: Question16
Examine Figure 8. Old icy surfaces are dark (from space
weathering), but young craters will excavate fresh clean ice and
will appear white. Put the four Galilean moons in order of age
of surface (from youngest surface to oldest surface).
• Callisto
• Europa
• Io
• Ganymede
Lab 5: Question 17

TRUE/FALSE: The age of the surface of a moon indicates the
level of geologic activity on that moon. For the Galilean
satellites, geologic activity is caused by a heating mechanism
related to Jupiter's gravitational pull.
Saturn's Moon: Titan
Background
Saturn's largest moon Titan is slightly larger than the planet
Mercury (about 6%, or 1.06 times larger), and is the only moon
in the solar system with a thick atmosphere (air pressure on the
surface of Titan is about 1.5 times that at the surface of the
Earth). As with Venus, thick clouds in Titan's atmosphere
prevent orbiting spacecraft from viewing the surface in visible
light. The Cassini spacecraft imaged Titan's surface in
ultraviolet and infrared light, and used radar to map features on
the surface. The Huygen's lander sent back images in visible
light from a small area on the surface after it got beneath Titan's
cloud layer.
As discussed in
Lab 4
, a
topographic map
uses color coding to indicate the relative elevation (highs and
lows) of landforms, such as plains, volcanoes, impact craters,
etc. Generally, violet and blue are used for low elevations,
shades of green for average elevations, and
yellow/brown/orange/red/white for high elevations.
A
geologic map
uses different colors to represent different types of rocks
and/or deposits on the surface of a planet (such as sand dune,
lakes, etc.), as well as locations of tectonic structures such as

faults, rift valley, volcanoes, etc.
Exploring Titan
Below is a topographic map for Titan.
Figure 9. Topographic map of Titan's surface. Source:
NASA
.
Lab 5: Question 18
Looking at the elevation scale on Figure 9, what is the total
change in elevation (in meters) on the surface of Titan (from
lowest to highest elevation)? Enter a single number only. [Hint:
you should look at the elevation scale for this information -
what you can actually see depends on how large or small you
make the image.]
Lab 5: Question 19
Compare your answer to Question 18 with the elevation changes
for the terrestrial planets which you determined in last week's
lab. Titan's elevation change is more similar to _____________
than to the other terrestrial worlds.
• Mercury
• Venus
• Earth

• Earth's Moon
• Mars
Lab 5: Question 20
For the terrestrial world you chose in Question 19, compare that
world's elevation change to Titan's elevation change. The
elevation change on the terrestrial world from Question 19 is
_______ times that of Titan.
Lab 5: Question 21
Examine the distribution of high and low areas on Titan (Figure
9) and compare to the distributions of high/low areas on the
terrestrial worlds in last week's lab. The distribution of high
and low areas on Titan most closely resembles the distribution
of high and low areas on _____________ .
• Mercury
• Venus
• Earth
• Earth's Moon
• Mars
Below is a geologic map of Titan's surface. A color coded key

of features is included. An explanation of the key is given in
the figure caption.
Figure 10. Original caption: "The first global geologic map of
Saturn's largest moon, Titan, is based on radar and visible and
infrared images from NASA's Cassini mission, which orbited
Saturn from 2004 to 2017. Black lines mark 30 degrees of
latitude and longitude. Map is in Mollweide projection, a global
view that attempts to minimize the size or area distortion,
especially at the poles (although shapes are increasingly
distorted away from the center of the map). It is centered on 0
degrees latitude, 180 degrees longitude. Map scale is
1:20,000,000. In the annotated figure, the map is labeled with
several of the named surface features. Also located is the
landing site of the European Space Agency's (ESA) Huygens
Probe, part of NASA's Cassini mission. The map legend colors
represent the broad types of geologic units found on Titan:
plains (broad, relatively flat regions), labyrinth (tectonically
disrupted regions often containing fluvial channels), hummocky
(hilly, with some mountains), dunes (mostly linear dunes,
produced by winds in Titan's atmosphere), craters (formed by
impacts) and lakes (regions now or previously filled with liquid
methane or ethane). Titan is the only planetary body in our solar
system other than Earth known to have stable liquid on its
surface — methane and ethane." Source:
NASA/JPL
.
Lab 5: Question 22
Examine the geologic map of Titan. Most of the sand dunes
(the sand grains are composed of hydrocarbons) are located
______.

• near the equator
• in mid-latitudes, between the equator and poles
• near the poles
Lab 5: Question 23
Examine the geologic map of Titan. Most of the bodies of
liquid ethane-methane are located ______.
• near the poles
Lab 5: Question 24
Examine the geologic map of Titan. Most of the tectonically
disrupted regions are located ______.
• near the poles
Below is a colorized radar image of Kraken Mare, which is the
largest body of liquid ethane and methane on the surface of
Titan. Located near Titan's north pole, the "sea covers 154,000

square miles (400,000 square km), making it about five times
bigger than North America's Lake Superior. (
Space.com
) The Cassini spacecraft mapped the surface of Titan using
radar and "included a segment designed to collect altimetry (or
height) data, using the spacecraft's radar instrument along a
120-mile (200-kilometer) shore-to-shore track of Kraken Mare.
For a 25-mile (40-kilometer) segment of this data along the
sea's eastern shoreline, Cassini's radar beam bounced off the sea
bottom and back to the spacecraft, revealing the sea's depth in
that area. This region, which is near the mouth of a large,
flooded river valley, showed depths of 66 to 115 feet (20 to 35
meters). Scientists think that, for the areas in which Cassini did
not observe a radar echo from the seafloor, Kraken Mare might
be too deep for the radar beam to penetrate. Alternatively, the
signal over this region might simply have been absorbed by the
liquid, which is mostly methane and ethane. The altimetry data
for the area in and around Kraken Mare also showed relatively
steep slopes leading down to the sea, which also suggests the
Kraken Mare might indeed be quite deep."
NASA
Figure 11. Original caption: "This is a segment of a colorized
mosaic from NASA's Cassini mission that shows the most
complete view yet of Titan's northern land of lakes and seas.
Saturn's moon Titan is the only world in our solar system other
than Earth that has stable liquid on its surface. The liquid in
Titan's lakes and seas is mostly methane and ethane. Seas and
major lakes are labeled in the annotated version. The data were
obtained by Cassini's radar instrument from 2004 to 2013. In
this color scheme, liquids appear blue and black depending on
the way the radar bounced off the surface. Land areas appear
yellow to white. Kraken Mare, Titan's largest sea, is the body in
black and blue that sprawls from just below and to the right of

the north pole down to the bottom. Most of the bodies of liquid
on Titan occur in the northern hemisphere. In fact nearly all the
lakes and seas on Titan fall into a box covering about 600 by
1,100 miles (900 by 1,800 kilometers). Only 3 percent of the
liquid at Titan falls outside of this area." Source (image and
caption):
Wikipedia
Lab 5: Question 25
Short answer. The Cassini spacecraft was able to determine the
surface area covered by Kraken Mare, and it is about 5 times
larger than the surface area covered by Lake Superior. Why
can't we determine the volume of liquid in Kraken Mare?
Saturn's Moon: Enceladus
Enceladus is dissimilar from the moons examined above, as it is
not comparable in size to any of the terrestrial worlds, but is
much smaller. The image below compares Enceladus to the
British Isles. To put this into a more local context, the state of
Oregon is about 400 miles east-west and about 300 miles north-
south (
netstate
). Despite this, the Cassini spacecraft observed water erupting
from fissures on Enceladus, indicating that the moon has a
liquid water layer beneath its icy surface.
Figure 12. Original caption: Enceladus is only 314 miles (505
km) across, small enough to fit within the length of the United
Kingdom. Source:
NASA

Gravity measurements of Enceladus and the wobble in its
orbital motion suggest a 10 km deep ocean beneath a layer of
ice estimated to be between 30 km and 40 km thick. (
NASA
) With this information we can estimate a possible minimum
and maximum volume of liquid water beneath the icy surface on
Enceladus, using the same method that is shown for Europa
(section on Europa above).
Figure 13. Model for the interior of Enceladus (thickness of
layers is not to scale). The radius of the entire moon is 252.1
km; the radius of the ice layer (given in pale gray/blue) is
estimated to be 30 to 40 km thick, and the liquid water layer (in
dark blue) is estimated to be 10 km thick on average. The water
and ice layers cover a rocky interior (dark gray). Source:
NASA
.
In order to calculate the volume of water on Enceladus, you
need to know the radii to the top and bottom of the liquid water
layer. In order to ensure that you know this, enter your answers
for the possible radii into Mini Quiz 3, and check the feedback
for the correct answers before continuing with the main lab
quiz.
Mini Quiz 3
Find the minimum and maximum radius of the top of the water
layer, which is the radius for Enceladus minus its ice shell. For
the minimum radius, use the thicker ice shell; for the maximum,
use the thinner ice shell. Enter numbers in the boxes provided.

Question 1: Minimum rtop: _______________ km
Question 2: Maximum rtop: _______________ km
Find the minimum and maximum radius of the bottom of the
water layer (which is also the top of Enceladus’ rocky interior)
by subtracting the ice thickness and ocean depth from the radius
Question 3: Minimum rbottom: ________________ km
Question 4: Maximum rbottom: ________________ km
Enter your answers (a single number) in the boxes provided.
When you are done, please check the Mini Quiz 3 feedback. The
next question
depends on using the numbers given in the feedback,
regardless of whether your answers were marked correct or not.
Use these numbers, and not your answers
Please make sure you have the correct answers (given under
"View Feedback" after you submit your quiz). Use the correct
values in order to answer Questions 26 and 27 below.
Lab 5: Question 26

Use the formula for the volume of a sphere (Equation 6) to find
the minimum volume for Enceladus' ocean layer. The
minimum volume for Enceladus' ocean layer is __________
km3. Enter only a number. Do not use scientific notation and
do not include commas in the number.
Lab 5: Question 27
Use the formula for the volume of a sphere (Equation 6) to find
the maximum volume for Enceladus' ocean layer. The
maximum volume for Enceladus' ocean layer is __________
km3. Enter only a number. Do not use scientific notation and
do not include commas in the number.
Lab 5: Question 28
The estimated volume of water on Enceladus is __________.
• similar to, but slightly more than the volume of the
Mediterranean Sea
• similar to, but slightly less than the volume of the
Mediterranean Sea
• similar to, but slightly more than the volume of the Earth's
oceans
• similar to, but slightly less than the volume of the Earth's
oceans

Neptune's Moon: Triton
Of all the moons in our solar system, only Titan and Triton have
atmospheres; both composed mainly of molecular nitrogen (N2).
However, Titan's atmosphere is thicker than that of the Earth,
while Triton's atmosphere is extremely thin, with a surface
pressure only about 1/7000th that of the Earth. Unlike Titan,
Triton's surface is easily imaged from space.
The only spacecraft to visit Triton was Voyager 2, which flew
by the moon in 1989 and imaged the southern hemisphere of the
moon. Below is a simplified geologic map of Triton based on
the Voyager 2 images. You will want to examine a much larger
version of this image to answer the questions below. [
]. You should be able to magnify this; you can also download
and open with a photo viewer or paint program and magnify.
Figure 14. Simplified geologic map of Triton's southern
hemisphere. North is up, West is left, and East is right. Source:
Wikipedia
.
Lab 5: Question 29
Match the following descriptions to the correct terms.
• fractures or tectonic faults
• cryovolcanic lake

• oldest lands composed of dirty water ice plus nitrogen ice
• icy layer composed of nitrogen and methane with traces of
ammonia
• Cantaloupe Terrain
• Subpolar land
• South Polar Ice Cap
• Patera
• Planitia
• Cryolava Plateau
• Sulci
• Cavus
• Maculae
• Geyser
Lab 5: Question 30
Enlarge the image and look for impact craters. Which of the
following best describes crater on Triton?
• there are no impact craters on the surface of Triton, so it must
be constantly resurfaced (similar in age to Io)

• there are only a few impact craters on the surface of Triton,
so it must have a young surface (similar in age to Europa)
• there are a fair number of impact craters on the surface of
Triton, so it must have a moderately old surface (similar in age
to Ganymede)
• there are a lot of impact craters on the surface of Triton, so is
must have a very old surface (similar in age to Callisto)
Lab 5: Question 31
One of the areas is described as "dark spots of tholin (?)".
Tholins are organic molecules that can form when radiation
interacts with molecules containing nitrogen, carbon, and
hydrogen. These molecules can be in an atmosphere, or as ices
on a surface. These areas of possible tholins are located
_________.
• randomly over the entire moon
• randomly on the south polar cap
• only on a few areas of south polar cap ice that are at or near
the edge south polar cap
• randomly on the cantaloupe terrain
• only on a few areas of the cantaloupe terrain that are very far
away from the south polar cap
Lab 5: Question 32

There are red arrows that are listed as "direction of geyser
plumes" in the legend. Geysers of liquid nitrogen erupt straight
upward from the surface of the south polar cap. Then, the winds
in the thin atmosphere of Triton blow the liquid sideways.
Based on the arrows that you can see in the image, which way is
the wind blowing across the south polar cap?
• mainly from the south to the north
• mainly from the east to the west
• mainly from the north to the south
• mainly from the west to the east

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