1) Astronomers can use the light from stars to determine many of a star's intrinsic properties, including the star's surface temperature.

a) (7 pts) Name two changes that happen to a star's spectrum as the star's temperature increases. Briefly explain why each of these changes occurs ... what do these changes accomplish?

b) (7 pts) Explain why this kind of continuous radiation from stars is also called "blackbody radiation".

2) In "Cargo Cult Science", Richard Feynman referred to Mr. Young's experiment with rats as an ideal example of the scientific method in action.

a) (7 pts) Explain how Mr. Young's experiment was different from other similar experiments and why these differences made his work more valid in Feynman's opinion.

b) (7 pts) An example of the scientific method in action involved the solar neutrino problem. Briefly explain what this "problem" was and why (even before new evidence came out about different neutrino types) scientists didn't abandon the theory of nuclear fusion as a result of this problem.

3) We can use the principles of atomic emission and absorption to remotely determine the composition of an object just by looking at its spectrum.

a) (7 pts) Describe how an absorption line spectrum is generated, then briefly explain why this spectrum can be used to determine the composition of a cool gas cloud.

b) (7 pts) We understand spectral lines more clearly thanks to the pioneering work of Ernest Rutherford. Briefly describe how Rutherford discoverd the nature of the atom (that it is a dense nucleus surrounded by a cloud of relatively light electrons).

4) In "Philosophy and the Scientific Method", Pine talks about scientific and non-scientific ideas along with how we systematically advance our knowledge about the world via the scientific method.

a) (7 pts) According to Pine, what is the major weakness of a system of knowledge that relies on irrefutable beliefs (note well here that I am not asking for the definition of "irrefutable")?

b) (7 pts) An example of this systematic study in action is our study of the Sun's energy source. Explain why scientists discarded the idea that the Sun is powered by gravitational energy in favor of the nuclear fusion theory.

5) The constellation Aquila the Eagle is prominent in our Summer skies in the evening.

a) (7 pts) Briefly explain the mythology behind this constellation. Also, give a rough altitude and azimuth of where Aquila can be found at 10pm tonight.

b) (7 pts) Suppose two stars in Aquila (call them "A" and "B") are located at distances of 500 (A) and 1000 (B) light years from Earth. Star A is moving toward us along our line of sight with a speed of 100 meters/sec while star B is moving across our line of sight (all of its motion is transverse) with a speed of 200 meters/sec. State how and briefly explain why the light from each of these stars will be shifted (or not shifted) as seen from Earth.

6) Two applications of laser technology have been explored in this first part of the course, one related to Astronomy, the other related to highway safety.

a) (7 pts) Briefly explain how lidar works to measure the speeds of cars.

b) (7 pts) Briefly explain how adaptive optics works to improve the quality of images we see with our telescopes.

7) Because of our problems with energy generation, scientists are placing a lot of hope on the idea that we may be able to design a working fusion reactor in the future.

a) (8 pts) Two kinds of fusion reactions we've tried on Earth are inertial and magnetically confined. Describe how each reaction works.

b) (6 pts) The solar corona has temperatures approaching and exceeding the 10-15 million degree temperatures in the core of the Sun, yet no fusion occurs in the corona. Why not?

8) This question deals with interesting surface phenomena seen in the photosphere.

a) (4 pts) In a single sentence, explain why sunspots appear dark, despite having temperatures of 4000K and higher.

b) (4 pts) In a single sentence, explain how we know that sunspots are associated with intense magnetic fields.

c) (6 pts) Briefly explain the phenomenon of limb darkening.