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| Asteroids and Meteors |
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1. | On Venus we find little evidence for meteor craters less than 1 km in diameter. Why? |
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2. | One of your classmates notes that astronomers believe a K-T extinction level asteroid strikes the Earth on average once every 100 million years. He then says that since we know the last time it happened was 65 million years ago, we have 35 million years to go before we have to worry. What fallacy has he committed? |
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3. | Another of your classmates notes that since in a certain country statistics show that every third child born is a Catholic, Buddhist families there should plan to have only two children. What fallacy has she committed? |
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4. | Use the cratering rate curve (see the discussion of meteors in the history of the Moon) to make the following estimate. If the K-T extinction collision that may have killed the dinosaurs 65 million years ago is an event that happens to the Earth now every 10-100 million years, how often did such catastropic collisions occur at the very beginning of the Solar System 4.5 billion years ago? |
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5. | Suppose that K-T extinction level events occur for the Earth every 100 million years. Estimate the statistical chance that such an event will occur in your lifetime. |
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6. | What is the difference in the kinetic energy of an asteroid striking the Moon's surface with a velocity of 10 km/s and the same asteroid striking at 1 km/s? |
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7. | What definite statement can we make about the orbital period of an aten asteroid? |
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8. | Data from the Hipparcos satellite have allowed more precise motion for nearby stars to be determined than was possible before. By projecting the current observed motion forward in time, such data can tell us if any stars are likely to pass near Earth in the future. But by projecting such data backward in time, we can also investigate whether any stars have passed close to Earth in the past. Why might scientists interested in past mass extinctions of life on Earth be particularly interested in such data? |
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9. | The asteroid Ceres is observed to have a synodic period of 466.6 days as viewed from Earth. What is its sidereal period? How large is its semimajor axis? |