Astronomy 150 – Midterm Name:February 5, 2004 – Winter 2004 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.0 (3 pts) Iron has a density of about g/cm3, water has a density of g/cm3, and rocks have adensity of aboutg/cm3.I have said a number of times in class that “geological activity scales with size”.1 (4 pts) Explain what this means.2 (6 pts) Explain why this is.The table below shows the properties of three planets orbiting a star that is identical to our Sun. Use thesedata to answer the questions on this page.Planet Mass Radius Uncompressed Moment-of-Inertia[Earth = 1] [Earth = 1] Density [g/cm3] Factor [K]Frodo 1/6 1/2 6.0 0.40Sam 1/2 3/4 4.5 0.34Pippin 6 2 3.5 0.30For each of the three worlds, explain what the composition of the world is (2 pts), how the gravity comparesto Earth’s gravity [show your work] (3 pts), and how the mass is distributed in the interior (2 pts).3 (7 pts) FrodoComposition:Gravity:Interior Mass Distribution:4 (7 pts) SamComposition:Gravity:Interior Mass Distribution:5 (7 pts) PippinComposition:Gravity:Interior Mass Distribution:In class I showed this table of the history of the surface of Venus:Time [Byr] Event Evidence4.6 Origin All Evidence Erased4.4 - 4.0 Differentiation All Evidence Erased3.8 Late Heavy Bombardment All Evidence Erased3.8 - 0.5 Geological Activity All Evidence Erased0.5 - Now Geological Activity Measured Crater Density6 (8 pts) Explain why we think we know what happened on the surface of Venus from 4.5 - 0.5 billion yearsago even though there is no direct evidence.7 (10 pts) Sketch a plot of the crater density of the surface of Venus (5 pts) and explain why it looks differentfrom the crater density plot of the Mare surfaces on the Moon (5 pts). Make sure to label your axis, but donot worry about the numbers.The graph above is the phase diagram for carbon dioxide (CO2).8 (4 pts) Plot and label the position on the phase diagram that shows what the phase of CO2would be inthis room.9 (4 pts) How cold would you have to make this room so that CO2would be a solid?10 (8 pts) How would you change the conditions of this room so that CO2could exist as a liquid?11 (8 pts) I said that the Earth-Moon system lacks volatiles compared to the average composition of thesolar system. Explain what this means.12 (8 pts) Explain why the Giant-Impact and Fission theory do a good job of explaining the lack of volatilesin the Earth-Moon system (The answer for both theories is the same).13 (6 pts) The element Iridium (Ir) is very rare in the Earth’s crust but more abundant in the core. Explainwhy this is.14 (8 pts) Would you expect Ir to be abundant or rare on the surface of the Moon? Explain your answer.(Hint: there are good arguments on both sides; I am more interested in your
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