Geology 110: Earth and Space Science
Chapter 3 (Near-Earth Objects)
Homework
SELF-REFLECTION AND COMPREHENSION SURVEYS
Checkpoint 3.1, p. 56
#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 3.3, p. 57
#2: 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.
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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. 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.
Checkpoint 3.5, p. 60
#3: 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 3.9, p. 62
#4: Meteor Crater (see Figure 3.1) was formed by an NEO about the size of ______. a) a Car b) a Two-story house c) a 15-floor office building d) Mt. Everest
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Checkpoint 3.10, p. 62
#5: 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 (1,640 to 4,265 feet) deep and is approximately 90 km (56 miles) across. What type of crater is it? a) Simple b) Complex
Checkpoint 3.11, p. 63
#6: 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 (37 miles) across and rises about 3 km (2 miles) 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. Non-impact-related craters often form during volcanic activity. How can you tell if a crater on Mars is formed by impacts or volcanism?
Checkpoint 3.13, p. 65
#7: Imagine that two identical asteroids are approaching Earth’s orbit. One impacts
Earth, the other the moon. Both impacts produce craters in the same type of rocks. How will the craters compare? 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.
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Checkpoint 3.14, p. 65
#8: Two 1-kilometer-wide asteroids collide with Earth. The first asteroid strikes a desert area 1,000 km (620 miles) 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.
Checkpoint 3.17, p. 69
#9: A relatively small NEO with a diameter of 50 meters (164 feet) could generate a 500- to 1,000-meter (1640-3280 feet) wide crater; a 1-kilometer-diameter (.62 miles) NEO would form a 10- to 20-kilometer-wide (6 to 12 miles) crater; and the impact of a 10kilometer-wide (6 mile) 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 crater sizes.
Checkpoint 3.18, p. 69
#10: 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 .
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(Optional extra credit question)
#11: 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.) a) A, b) B or c) C (circle one) b)
Note : you must show or describe how you arrived at your answer for extra credit on
#11…
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