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| The Inner Planets |
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1. | Calculate the speed of a point on the equator of Mercury as Mercury rotates. How much of a Doppler shift would this motion cause? |
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2. | The rotational periods of Mercury and Venus were measured by bouncing radar signals off their surface to determine the Doppler shift caused by their rotational motion. For both Mercury and Venus, determine how long the wait is for the return signal when the planet is at closest possible approach to Earth. |
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3. | How much more energy from the Sun (per square meter) does Venus receive compared to Earth? |
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4. | The average surface temperature on Venus is 750 K and the average for Earth is 300 K. Use the Stefan-Boltzmann law to calculate how much more energy per square meter Venus' surface radiates compared to Earth. |
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5. | Compare the mass of the atmosphere of Venus to that of the planet Venus. What is the value of this comparison in the case of Earth? Approximate Venus' atmosphere as a layer of gas 50 km thick with uniform density of 21 kg/m3. |
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6. | Compare the day and night temperature differences for Venus, Earth, and the Moon. What are the differences, and why? |
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7. | Dissociation of water by UV radiation into hydrogen and oxygen in the upper atmosphere with the hydrogen then escaping to space is expected to increase the deuterium to mass-1 hydrogen ratio. Why? |
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8. | Craters on Venus have much less extensive ejecta blankets than for the Moon. Why? |
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9. | Exaggerated vertical relief like that commonly displayed in radar maps of Venus is also common in Earth maps. Find a globe with vertical relief shown for high mountains like the Andes or Himalayas. Use the known dimensions of some objects to estimate the height of the mountains on the globe if the relief shown were really correct. Compare with their known heights. (One source of information about actual heights of mountain ranges, etc. is a Web search engine.) |
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10. | The rotational period of Venus is 243 days, but the Sun returns to the celestial meridian every 117 days as observed (if you could) from the surface of Venus. Explain. |
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11. | On Earth the solar day is longer than the sidereal day but on Venus it is shorter. Why? |
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12. | Volcanoes on Venus appear to have been mostly of the fluid lava flow type. There is little evidence for explosive eruptions (like that of Mount St. Helens on Earth). Can you think of at least two reasons why explosive eruptions would be less likely on Venus? Hint: what powers explosive eruptions on Earth? |
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13. | On Earth the "lowlands" (sea floor) are much younger on average than the "highlands" (continents), but on Venus the opposite is true: lowlands are older and highlands are younger. Explain. |
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14. | Use the planetary solar day calculator to calculate the length of the solar days on Venus and Mercury. |
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15. | Compare geologically the areas of highest elevation ("highlands") on the Moon, Venus, and the Earth; repeat for the areas of lowest elevation. Each differ fundamentally on the three bodies. List some of these differences; speculate (as far as possible; we still don't understand the differences fully) on possible reasons for these differences. |
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16. | Repeat Exercise 15, but add Mercury to the list. |
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17. | Neither the Moon nor Mercury have atmospheres so sunlight falls directly on their surfaces with little attenuation. Use inverse square intensity law to determine the ratio of sunlight intensity falling on each square centimeter of Mercury and the Moon. |
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18. | Most people find a comfortable room temperature with average humidity to be about 70-75 degrees on the Farenheit scale. Researchers find, however, that this is because we normally wear clothes. For people with no clothes on, it is found that a room temperature of 84 degrees F is most comfortable. Explain this difference in terms of the same principles that govern the temperatures of planetary atmospheres. |
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19. | Contrast the heavy metal abundances of Mercury and the Moon. |
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20. | Calculate the synodic period of Mercury from its sidereal period. |
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21. | Show that the solar day is equal to twice the length of the sidereal year on Mercury. |