Geology 110: Earth and Space Science
Chapter 3 (Near-Earth Objects)
Homework
SELF-REFLECTION AND COMPREHENSION SURVEYS
Checkpoint 3.1, p. 62
#1: Which characteristics are true of both planets and asteroids?
a) They are approximately spherical in shape.
b) There are thousands of examples.
c) They formed 1 to 2 billion years ago.
d) They are present in the solar system.
Checkpoint 3.2, p. 62 (FOR NOTEBOOK ONLY…message for online classes)
#2: Compare and contrast the characteristics of the planets (see Chapter 2) in our solar
system with those of asteroids by placing the numbers from the list of characteristics in
the most suitable locations on the diagram. Characteristics 4, 7, and 10 have been plotted
for you.
10
7
4
1. Radius greater than 500 km
2. Essentially spherical in shape
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3.
4.
5.
6.
Orbit the Sun
Have a gravitational field
Can rotate
May be made of materials similar to
those found on Earth
7. Possess moons
8. Thousands of examples
9. Have atmospheres
10. Have less predictable orbits
11. Have a variety of shapes
12. Formed after the Big Bang over 4
billion years ago
13. Have craters
14. Some will collide with Earth
15. Example: Mars
16. Example: Eros
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Checkpoint 3.3, p. 63
#3: Read the article below and answer the questions that follow. Consider the difference
among observations, hypotheses, and predictions.
Asteroid Crashes the Moon?
Early in the morning of November 15, 1953, amateur astronomer Leon Stuart was
looking at the surface of the Moon through his homemade telescope. As he watched, he
saw a bright flash that seemed to come from the lunar surface. He was able to snap a
photograph of the event on a camera connected to the telescope. Stuart published the
image in a journal for amateur astronomers and wrote a short article that interpreted the
flash to represent the only known record of an asteroid crashing into the Moon. Stuart’s
interpretation has been challenged over the years since its publication. Some scientists
have suggested that what he actually observed was a “point meteor,” an asteroid
burning up in Earth’s atmosphere as it moved directly toward the observer. In this
interpretation, the Moon would just have been present in the background behind the
burning meteor. Those who support this interpretation point out that the flash was
observed for 8 seconds, much longer than would be expected for a meteorite impact.
Jump forward to 2001. Dr. Bonnie Buratti and her research assistant compared images
of the Moon’s surface taken by the Clementine spacecraft in 1994 with Stuart’s original
photograph. They estimated the size of crater that would have been formed by the Stuart
event based on the size and brightness of the flash. They discovered a small, “freshlooking” crater of the appropriate size in the center of their search area and inferred it to
represent the crater formed by the meteorite impact. Their results were published in the
astronomy journal, Icarus in January 2003. Still, many astronomers were skeptical. Soon
after publication of Buratti’s article John Westfall, an expert on the features of the lunar
surface, examined archive photographs taken by the 100-inch Mt. Wilson telescope in
1919 and found the same crater. Clearly, it could not be the product of a 1953 meteorite
impact if it was already present in 1919! The mystery continues.
Sources: New York Times, March 4, 2003, by Henry Fountain; Toronto Star, March 9,
2003; Jet Propulsion Lab, Cal Tech.
1. Which of the following represents a key hypothesis presented in this article?
a) Meteorites do not collide with the Moon very often.
b) Craters on the moon are formed by meteorite impacts.
c) A meteorite impact on the moon was photographed in 1953.
d) Most young craters on the moon have a “fresh” appearance.
2. What was the principal observation used to support the hypothesis?
a) An article appeared in an amateur astronomy journal article.
b) Leon Stuart photographed a bright flash on the moon’s surface.
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c) Dr. Buratti found a recently formed crater on images of the moon taken by the
Clementine spacecraft.
d) Meteorites hit the moon once or twice a century.
3. What was the key prediction that was tested in an attempt to prove the hypothesis?
a) A small, fresh-looking crater would be present in a specific location.
b) A bright flash would be visible on the moon’s surface.
c) Craters would be present on the moon.
d) A meteorite could be observed at the location of Stuart’s original photograph.
4. Which hypothesis was falsified in this article?
a) The bright flash represented a point meteor.
b) An asteroid collided with the moon on November 15, 1953.
c) A crater photographed by the Clementine spacecraft was formed by the impact
event.
d) The Mt. Wilson telescope observed the same crater in 1919.
e)
Checkpoint 3.4, p. 64
#4: Review the four student-generated concept maps, all of which describe some of the
basic characteristics of asteroids. Your task is to identify which diagram best represents
the most important features of asteroids. Rank the concept maps in order from best (1) to
worst (4) and justify your rankings. Your justification should include a description of the
criteria you used to decide what makes one map better than another.
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Rank Order: 1. ___ 2. ___ 3. ___ 4. ___
Checkpoint 3.5, p. 66
#5: Where is the Kuiper Belt relative to the Asteroid Belt?
a) The Kuiper Belt is closer to the sun than the Asteroid Belt.
b) The Kuiper Belt is farther from the sun than the Asteroid Belt.
c) The Kuiper Belt and Asteroid Belt are located in the same region of the solar system.
Checkpoint 3.6, p. 66
#6: Examine the three figures below showing the location of a comet as it approaches the
sun. Consider the orbits of Earth and the comet. In which scenario is the comet most
likely to pass most closely to Earth? (Hint: Comets travel at speeds of approximately 10
million km/day; Mars is nearly 80 million km farther from the Sun than Earth. Diagram
not drawn to scale.)
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a) A,
b) B
or
c) C
(circle one)
Checkpoint 3.7, p. 67 (Not Required/Not Extra Credit…all classes)
#7: Complete the following Venn diagram to compare and contrast the similarities and
differences between planets and comets (see Chapter 2). Add more characteristics to the
following list, and place the numbers corresponding to the appropriate characteristics in
the most suitable locations on the diagram. Two have been provided as examples.
2
1
1. Diameter greater than 1000 km
2. Orbit the Sun
3.
4.
5.
6.
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7.
8.
9.
10.
11.
12.
Checkpoint 3.8, p. 68 (NOT REQUIRED/NOT EXTRA CREDIT…all classes)
#8: Create a concept map that shows the main characteristics of NEOs, including both
asteroids and comets. Use at least 10 terms.
Checkpoint 3.9, p. 69
#9: Meteor Crater (see Figure 3.1) was formed by an NEO about the size of a ______.
a) Car
b) Two-story house
c) 15-floor office building
d) City block
Checkpoint 3.10, p. 69
#10: Imagine you are a scientist who recently discovered an impact crater beneath
Chesapeake Bay along the Atlantic coast. The crater is 500-1,300 meters deep and is
approximately 90 km across. What type of crater is it?
a) Simple
b) Complex
Checkpoint 3.11, p. 70 (EXTRA CREDIT..all classes)
#11: Examine the accompanying image of the Uranius Tholus volcano from Mars (taken
from NASA’s Viking I orbiter in 1977). The volcano is 60 km across and rises about 3
km from the surrounding plain. Describe the impact craters that you can identify from the
image and discuss the relative age of formation of the craters and the volcano. Nonimpact-related craters often form during volcanic activity. How can you tell if a crater on
Mars is formed by impacts or volcanism?
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Checkpoint 3.12, p. 71 (EXTRA CREDIT…All Classes)
#12: Imagine that you are a member of a team of scientists who are drilling into a large
crater approximately 200 km wide. The crater was formed by an NEO impact that wiped
out many species 251 million years ago. The drilling team will recover rock samples
during the drilling process. You have some data to suggest that the crater is located
between 500 and 1,500 meters below the surface. How will the drilling team know when
the drill reaches the crater? What features will they observe?
Checkpoint 3.13, p. 72
#13: Imagine that two identical asteroids crashed into the same type of rocks on the
surface of the moon and Earth. Both impacts produce craters. How will the craters
compare? Explain why you chose this answer.
a) The crater on the moon will be larger.
b) The crater on Earth will be larger.
c) The craters will have the same dimensions.
Checkpoint 3.14, p. 72 (NOT REQUIRED, NOT EXTRA CREDIT…all classes)
#14: Two 1-kilometer-wide asteroids collide with Earth. The first asteroid strikes a desert
area 1,000 km from the city of Bang with a population of 1 million people. The other
lands in the open ocean 1,000 km from an identical city named Crash that also has 1
million people. Both cities are located along a low-lying coast similar to the Atlantic
coast of the eastern United States. Predict which city will suffer the most damage.
Explain your choice.
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Checkpoint 3.15, p. 73 (EXTRA CREDIT…all classes)
#15: Review the following concept map developed by a student, which describes the
characteristics of NEO impacts. Score the concept map using the grading rubric, and
redraw the diagram, making whatever changes you believe are appropriate to earn a 4 on
the grading scale.
Grading Rubric
0
The concept map does not contain
any information about NEO impact
events.
1
The concept map contains some
relevant terms, but several key terms
are omitted and many linking phrases
are either absent or inaccurate.
2
The concept map contains most of
the relevant terms, but they are
poorly organized and some linking
phrases are absent or incorrect.
3
The concept map contains most of
the relevant terms, but one or two
key terms may be absent. The
diagram is reasonably wellorganized, and almost all linking
phrases are appropriate.
4
The concept map contains all
relevant terms in a well-organized
display that has appropriate linking
phrases for each pair of terms.
Checkpoint 3.16, p. 73
#16: Scientists have recently discovered the existence of a 90-kilometer-wide crater
beneath Chesapeake Bay in the eastern United States. What would happen if the same
impact event were to happen today? Examine the map that shows the location of
Chesapeake Bay relative to major cities and physical landforms. What would be the
effect on the United States and the world? How would this event compare to the
Chicxulub impact?
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Checkpoint 3.17, p. 76
#17: A relatively small NEO with a diameter of 50 meters could generate a 500- to 1,000meter wide crater; a 1-kilometer-diameter NEO would form a 10- to 20-kilometer-wide
crater; and the impact of a 10-kilometer-wide NEO would result in a crater 100 to 200 km
across. Identify features around your campus or city that have similar dimensions to these
three sizes of crater. (1 kilometer=0.62 miles)
Checkpoint 3.18, p. 77 (EXTRA CREDIT ONLY…all classes)
#18: Go to the NASA NEO site at http://neo.jpl.nasa.gov/ . Select the “Close
Approaches” icon. Review the “Upcoming Close Approaches to Earth” table. Find the 5
closest approaches and evaluate which one would be most threatening if it were to
actually impact Earth. Support your choice.
Checkpoint 3.19, p. 78 (NOT REQUIRED/NOT EXTRA CREDIT…all classes)
#19: Discuss how the characteristics of the scientific method are apparent in the use of
the Torino Scale and the search for NEOs.
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Checkpoint 3.20, p. 78 (MESSAGE FOR ONLINE CLASSES; YOU SHOULD BE
ABLE TO TYPE YOUR ANSWERS INTO THE TABLE…also, this would be a
good question to work on with other students under the discussion tool)
Asteroid Impact Risk Evaluation Rubric
It is 20 years in the future. Scientists have catalogued all the largest NEOs (diameter 1
kilometer or greater) and have found that none pose a threat to Earth. Ten years ago, they
began to work to identify all NEOs with a diameter of 50 meters or greater that have a
trajectory leading them toward Earth. Advances in tracking technologies now allow
scientists to accurately pinpoint the location where such objects will strike the surface of
the planet. So far, they have found four asteroids that will collide with Earth.
Governments from around the world have contributed to an international fund to
support a mission to destroy the most dangerous of the four asteroids. You are on a team
charged with choosing which asteroid to target for destruction first.
1. You are given the assignment to create an evaluation rubric to assess the relative
dangers from the four asteroids. You must find a method of ranking the risk of
potential harm from each impact event. Consider what factors would contribute to
the loss of lives and high damage costs associated with an impact. One factor
(size) has been done for you as an example (see accompanying table). After
identifying at least four more factors, distinguish what characteristics related to
impact hazards would make each of them a high-, moderate-, or low-risk
phenomenon. Consequently, large NEOs are given a high-risk score (3 points),
whereas smaller asteroids are viewed as low risk (1 point). Add your data to the
table. You will then use the combination of factors with the highest cumulative
score to identify which incoming asteroid will be destroyed first.
2. After completing your rubric, your team is asked to double the score of the most
important factor. Which factor would you choose? Why? Explain your choice.
Standards and criteria: You will be assessed on your choice of:
i. Relevant factors that would contribute to the potential for damaging impacts.
ii. Identification of what constitutes high/moderate/low risk situations for each factor.
iii. Your justification for choosing one factor in particular as the most significant.
Factors
Low Risk
(1 point)
Moderate Risk
(2 points)
High Risk
(3 points)
Small
Intermediate
Large
iv.
Size
(diameter) of
asteroid
(diameter approximately
50 meters)
(diameter 50-500
meters)
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(diameter more than
500 meters)
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Question 3.21, p. 79
#21: Note the interactions between Earth System Components in the following concept map
(review and understand and think of others; no answer required here).
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