Chapter 3 Checkpoint 3.1 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 Venn Diagram: Planets versus Asteroids 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. 1. Radius greater than 500 kilometers 2. Essentially spherical in shape 3. Orbit the sun 4. Have a gravitational field 5. Can rotate 6. 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 Checkpoint 3.3 Asteroid Crashes the Moon? Read the following article and then answer the questions concerning the differences 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 fl ash 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 fl ash as the only known record of an asteroid crashing into the moon. Over the years since its publication, Stuart s interpretation has been challenged. 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 simply have been present in the background behind the burning meteor. Those who support this interpretation point out that the fl ash 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 a crater that would have been formed by the Stuart event on the basis of the size and brightness of the fl ash. They discovered a small, fresh-looking 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-in 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. Questions 1. Which of the following represents a key hypothesis presented in this article? a. Meteorites don t 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. 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 key prediction 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 3.4 Concept Maps of Asteroids Review the following four 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. Rank order: 1. 2. 3. 4. Comprehension Survey: Section 3.2, Part 1 the material in this section. Answer the corresponding questions. I can identify some basic features of an asteroid. (Answer Checkpoint 3.1.) I can compare and contrast the characteristics of planets and asteroids. (Answer Checkpoint 3.2.) I can apply the scientific method to a news story about an NEO. (Answer Checkpoint 3.3.) I can evaluate features and concepts related to asteroids. (Answer Checkpoint 3.4.) Checkpoint 3.5 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 the Asteroid belt are located in the same region of the solar system. Checkpoint 3.6 Examine the following three figures 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 likely to pass most closely to Earth? (Hint: Comets travel at speeds of approximately 10 million km/day; Mars is nearly 80 million kilometers farther from the sun than Earth. Diagram not drawn to scale.) Checkpoint 3.7 Venn Diagram: Planets versus Comets 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. 1. Diameter greater than 1,000 kilometers 2. Orbit the sun 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Checkpoint 3.8 Create a concept map that shows the main characteristics of NEOs, including both asteroids and comets. Use at least 10 terms. Comprehension Survey: Section 3.2, Part 2 the material in this section. Answer the corresponding questions. I can compare the sources of asteroids and comets. (Answer Checkpoint 3.5.) I can predict the potential for a comet to pass by Earth. (Answer Checkpoint 3.6.) I can compare and contrast the characteristics of planets and comets. (Answer Checkpoint 3.7.) I can combine concepts from this section of the chapter to create a concept map that illustrates the main characteristics of NEOs. (Answer Checkpoint 3.8.) Checkpoint 3.9 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 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 approximately 90 kilometers across. What type of crater is it? a) Simple b) Complex Checkpoint 3.11 Examine the accompanying image of the Uranius Tholus volcano from Mars (taken from NASA s Viking 1 orbiter in 1977). The volcano is 60 kilometers across and rises about 3 kilometers 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 3.12 Imagine that you are a member of a team of scientists who are drilling into a large crater approximately 200 kilometers 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 m below the surface. How will the drilling team know when the drill reaches the crater? What features will they observe? Comprehension Survey: Section 3.3 the material in this section. Answer the corresponding questions. I can infer the relationship between the size of an impact crater and an NEO. (Answer Checkpoint 3.9.) I can predict the type of crater based on its size. (Answer Checkpoint 3.10.) I can compare and contrast craters formed by volcanism and NEO impacts. (Answer Checkpoint 3.11.) I can describe the features that would be observed during drilling a crater formed by an NEO impact (Answer Checkpoint 3.12.) Checkpoint 3.13 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? 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 Two 1-kilometer-wide asteroids collide with Earth. The first asteroid strikes a desert area 1,000 kilometers from the city of Bang with a population of 1 million people. The other lands in the open ocean 1,000 kilometers 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 3.15 Concept Map of NEO Impacts 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 well organized, and almost all linking phrases are appropriate. 4 The concept map contains all of the relevant terms in a well-organized display that has appropriate linking phrases for each pair of terms. Checkpoint 3.16 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?
Comprehension Survey: Section 3.4 the material in this section. Answer the corresponding checkpoint questions. I can contrast the size of impact craters on Earth and the moon. (Answer Checkpoint 3.13.) I can infer how the location of an impact site influences the potential for damages. (Answer Checkpoint 3.14.) I can analyze a concept map that illustrates the characteristics of impact events. (Answer Checkpoint 3.15.) I can evaluate the potential consequences of a present-day impact event on a U.S. site. (Answer Checkpoint 3.16.) Checkpoint 3.17 A relatively small NEO with a diameter of 50 meters could generate a 500- to 1,000- meter-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 kilometers across. Identify features around your campus or city that have similar dimensions to these three crater sizes. (1 kilometer = 0.62 miles) Checkpoint 3.18 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 three closest approaches and evaluate which one would be most threatening if it were to actually impact Earth. Support your choice. Checkpoint 3.19 Discuss how the characteristics of the scientific method are apparent in the use of the Torino scale and the search for NEOs.
Checkpoint 3.20 Asteroid Impact Risk Evaluation Rubric It is 20 years in the future. Scientists have cataloged all the largest NEOs (diameter 1 kilometer or greater) and have found that none of that size pose a threat to Earth. Ten years ago, they began trying to identify all NEOs with a diameter of 50 meters or greater and 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 are supporting 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. Your assignment is 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 the 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. The larger the asteroid, the greater the risk. 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: Relevant factors that would contribute to the potential for damaging impacts. Identification of what constitutes high/moderate/low-risk situations for each factor. Your justification for choosing one factor in particular as the most significant. Factors Low risk (1 point) Moderate risk (2 points) Size (diameter) of asteroid Small (diameter approximately 50 meters) Intermediate (diameter 50 500 meters) High risk (3 points) Large (diameter more than 500 meters)
Comprehension Survey: Section 3.5 the material in this section. Answer the corresponding Checkpoint questions. I can identify the relationship between the size of an NEO and the impact crater it would produce. (Answer Checkpoint 3.17.) I can identify the relative threat posed by NEOs approaching Earth. (Answer Checkpoint 3.18.) I can explain how elements of the scientific method are evident in the search for threatening NEOs. (Answer Checkpoint 3.19.) I can evaluate the features to consider in weighing the potential risks for asteroids colliding with Earth. (Answer Checkpoint 3.20.)