Astronomy 120: Fall 2008

Homework 8: Due in October 31/November 3 recitation

Name ___________________________ Section _______

1. (from the book, Chapter 11) Suppose the jovian planet atmospheres were composed only of hydrogen and helium, with no hydrogen compounds at all. How would the atmospheres be different in terms of clouds, color, and weather? Explain in about 10 - 15 lines of clear handwriting (or typing).

    

    

    

    

2. Saturn's ring system is about 300,000 km wide, and only about 30 meters thick. Assuming the rings could be shrunk down so that their diameter is the same as a DVD (12 cm), how thick would the rings be? Compare your answer to the actual thickness of a DVD (0.12 cm) - how many times thicker (or thinner) is a DVD compared to the shrunk-down Saturnian ring system?.

    

    

    

    

3. When we discussed the formation of the moon via the "Giant Impact Theory" we found that the model requires a collision between the early Earth and a Mars-sized protoplanet. The collision splashed off the material from the outer parts of the Earth which gathered together at a distance from the Earth to make up our moon.

   Now, having learned a bit about ring systems and tidal effects in the Jovian planets, you can explore this model a bit further.

   1. How far away from the surface of the Earth did the material have to get so that it could collect together under its own gravity?
   2. Why could it have not formed any closer?
   3. What do you think happened to the material that was inside this distance after the initial collision?