1) The properties of blackbody radiation help explain why stars have the colors that they appear to have, based on their temperatures.

a) (6 pts) Explain in a couple of sentences why the peak wavelength of emission for an object is inversely proportional to the objectıs temperature.

b) (8 pts) Why does energy travel outward in the form of light from the surface of a star? Also, why does it *not* travel in the form of light in the convection zone of a star?

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2) Below is an energy level diagram for an atom of element X:

Suppose an atom of element X has an electron in the level E=2. State below (yes or no) which of these energies can be absorbed by this atom. No explanations are required for this problem:

E = 2 ________________

E = 7 ______________

E = 3 ________________

E = 9 ______________

E = 5 ________________

E = 10 ______________

3) The temperature of the photosphere gets hotter as one looks deeper beneath the surface, and the temperature of the corona gets hotter as one looks further above the surface.

a) (7 pts) Explain the evidence that tells us about this temperature trend in the photosphere. How do we know it is hotter deeper inside?

b) (7 pts) Explain how observations of ionization species tell us the corona gets hotter as one looks further from the Sun (as part of your answer, explain what ionization species are and why different species are present at different temperatures).

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4) Although temperatures in the corona are comparable to temperatures in the core of the Sun, nuclear fusion doesnıt occur in the corona because the density is so much lower than the density in the core of the Sun.

a) (7 pts) Explain why a gas needs to be dense in order for nuclear fusion to occur.

b) (7 pts) Explain how the low density in the corona contributes to the high temperatures in the corona.

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5) The reading "Philosophy and the Scientific Method" covers several topics that are vital to understanding scientific thinking.

a) (8 pts) The author explains that irrefutable beliefs are very compelling since they offer a secure finality to our views, helping us to face life's contingencies and uncertainties. Explain the major weakness of irrefutable beliefs (donıt just say "theyıre irrefutable" or words to that effect...go into why thatıs a problem for science).

b) (6 pts) The author explains that both scientific and nonscientific ideas lead to seemingly unbelieveable conclusions, such as apocalyptic predictions, "quantum tunneling" or "black holes", but scientific ideas are more useful because of an important distinction. What is the major difference between these two kinds of ideas?

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6) Explain why spectral line widths are related to the temperature of a gas.

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7) The solar neutrino problem was recently resolved by a complex neutrino detection experiement.

a) (8 pts) Explain two possible resolutions to the solar neutrino problem (one dealing with neutrinos themselves, the other with the Sunıs core conditions).

b) (6 pts) For a long time, despite the fact that the neutrino problem was unresolved and an apparent contradiction to the standard model of the Sunıs interior, scientists still refused to abandon the theory of nuclear fusion to explain the Sun. Explain why.

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8) Astronomers have always used big telescopes to collect the most useful data on objects in our night sky. Knowing a lot about these instruments helps one understand how to be a more effective researcher.

a) (6 pts) Why do radio telescopes have poorer resolution than optical telescopes? Explain.

b) (8 pts) Briefly explain how interferometry is used to help overcome this problem. Why canıt interferometry be used with optical telescopes for similar enhancement? Explain.