Astronomy 150 - Midterm Name: April 30, 2009 TA?s Name & Section (2 pts): Answer all questions in the space provided. If you have any questions, raise your hand. 100 points possible. NO CALCULATORS OR ANY ELECTRONIC DEVICES. Four planets are orbiting a star that is identical to our Sun. We have observed these planets and collected the following data. Use these data for the entire exam! Planet Mass Diameter Density Moment of Distance from [Earth = 1] [Earth = 1] [g/cm3] Inertia factor [K] star [AU] Ardbeg 0.5 0.7 5.8 0.34 0.3 Bowmore 0.8 0.9 4.4 0.36 0.7 CaolIla 8.0 2.0 4.0 0.30 1.0 Dalmore 0.1 0.5 3.1 0.40 1.5 1 (3 pts) If we assume that these planets are made of the same materials as our solar system (ice, rock and iron) what is the most likely compositions of the planet Dalmore? 2 (6 pts) Which of the planets is least differentiated? Make sure to explain your answer. 3 (8 pts) How does the gravity on CaolIla compare to the gravity on the Earth? Make sure to show your work. 4 (6 pts) Explain why the planet CaolIla would be the most likely of the four planets to still be geologically active today. 5 (2 pts) What type of rock would be most common on a geologically active surface of CaolIla? 6 (8 pts) You already determined how the gravity on CaolIla compares to the Earth. Based on this, would expect the mountains on CaolIla to be shorter or taller than the ones on Earth? [Explain your reasoning] 7 (8 pts) What is the type and age of the youngest rock you would expect to find on the surface of Dalmore? Be as specific in the age and type as you can. 8 (8 pts) Explain why you would not use a radioactive element like Carbon-14 (half-life = 5,730 years) to determine the age of the surface of Dalmore. To explore the planets, you send an orbiter/lander sample-return mis- sion to the planetary system. The orbiter collects the following data about the planetary atmospheres: Planet Surface Pressure Surface Temperature Composition [atm] Range [?C] Ardbeg . . . ?100 ? 300 No Atmosphere Bowmore 1.0 0 ? 75 96% CO2 CaolIla 5.0 90 ? 95 95% CO2 Dalmore . . . ?300 ? ?100 No Atmosphere 9 (4 pts) Hydrogen is the most common gas in the universe, yet none of these planets has hydrogen in its atmosphere. Explain why this is. 10 (4 pts) Planets Bowmore and CaolIla have atmospheres that are rich in CO2. Where did this CO2 come from? 11 (8 pts) Explain why the variation in surface temperature is much larger on Bowmore than on CaolIla. Your lander on CaolIla discovers the sub- stance called Oobleck on the surface. The phase diagram for Oobleck is shown at the right. 12 (3 pts) What is the phase of Oobleck on the surface of CaolIla? Solid Liquid Gas 1 2 4 5 3 Temperature (C) Pressure (atm) 0 25 50 75 100 Liquid Solid Gas 13 (3 pts) What is the phase of Oobleck high in the atmosphere of CaolIla? Solid Liquid Gas 14 (3 pts) What would the phase of Oobleck be in this room? Solid Liquid Gas 15 (8 pts) Based on the data given on the previous pages, explain why you would not expect to find life (like it occurs on Earth) on any of these worlds. 16 (8 pts) In the space below sketch and label the crater density diagram for CaolIla and Dalmore. 17 (8 pts) Explain why the impact of a 5 km asteroid would have a far larger global effect on Bowmore than on Ardbeg.
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