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hw3solution - ASTRO 101 HOMEWORK 3 1. What evidence do we...

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ASTRO 101 HOMEWORK 3 1. What evidence do we have to support the theory that climate on Mars has changed? (4 points) Riverbeds, river channels, river deltas, and evidence that islands or lakes once existed imply that Mars once had an abundance of running water. In addition, gullies cut by moving water (water erosion) can be seen in the walls of many impact craters and on the sides of the giant Martian fault canyon. Along the floor of the canyon you can see sedimentary deposits that have been exposed by wind and water erosion. These observations imply that Mars once had both greater atmospheric pressure and greater surface temperature. Since today Mars has very low atmospheric pressure (<1% atm) and lower surface temperature (greenhouse gases are in atmosphere or frozen in polar caps or permafrost), the climate must have been very different in the past. In addition we see currently inactive volcanoes (like Olympus Mons) and uplifted highlands (Tharsis bulge). In the past, volcanic eruptions introduced carbon dioxide and water vapor into the atmosphere, which would have contributed to more of a greenhouse effect than exists on Mars today. 2. The atmospheres of Venus and Mars are dominated by carbon dioxide. Earth has a very different atmosphere. Describe the Earth’s atmosphere and explain why it is so different. (4 points) Earth’s atmosphere is about 78% N
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This note was uploaded on 05/18/2008 for the course ASTR 300 taught by Professor Cramton during the Spring '08 term at Maryland.

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hw3solution - ASTRO 101 HOMEWORK 3 1. What evidence do we...

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