Exam 3.

NAME:________________________












































I. In the space next to each statement, write either "T" for TRUE, or "F" for FALSE. (1 pt. ea.)

_____ 1. At noon on the northern hemisphere's longest day of the year, the Sun does not stand directly overhead in the continental U.S.

_____ 2. Elements with more protons than iron were formed in supernovae.

_____ 3. Just before a lunar eclipse, the moon is new.

_____ 4. A closed universe will expand forever.

_____ 5. Kepler believed planets' orbits were circular, since he thought circles to be perfect forms.

_____ 6. As you move away from the equator, the size of the circumpolar region you see increases.

_____ 7. The Sun's energy comes from fusing 4He into 1H.

_____ 8. In the northern hemisphere, the Sun rises south of east in the winter.

_____ 9. A K-type star excites higher energy spectral transitions than an A-type star.

_____ 10. The cosmic microwave background is hotter now than it was in the past.

_____ 11. Red light scatters more easily than blue light.

_____ 12. The wavelength of a spectral line depends on temperature.

_____ 13. The Sun lies directly over the Tropic of Capricorn on the northern hemisphere's winter soltsice.

_____ 14. Shorter wavelength spectral lines are excited in higher temperature stars.

_____ 15. Comets' ion tails point away from the Sun, while their dust tails trail behind them along their orbital path.















II. For each question below, provide a brief (1-5 words) answer. (3 pt. ea.)

1. When the Moon rises at noon, what is its phase?



2. At which two phases of the Moon should you expect higher tides than usual?



3. To determine that the Milky Way's core houses a supermassive black hole, astronomers tracked stars near the core as they moved across our sky. What do we call these stars' apparent changes in position?



4. a) Theoretically, what is the largest mass a white dwarf can have before it collapses into a neutron star? (This mass is known as Chandrasekhar's limit.)

b) Once a white dwarf has collapsed into a neutron star, what keeps it from collapsing further?


5.b) How many years does it take the Sun's field to both reverse itself and return to its original configuration?


b) How many years does it take the Sun's field to both reverse itself and return to its original configuration?



III. Matching: Next to each distance indicator below, write the letter corresponding to the GREATEST distance at which it is useful. Obviously, you can use each maximum range more than once. (5 pt.)

Distance Indicator
variable stars ______
radar ______
parallax ______
Hubble shifts ______
main seq. fitting ______
useful range
a) within solar system
b) within/near Milky Way
c) other spiral galaxies










IV. Multiple choice - circle the correct answer from the choices provided.

1. In the figure above, a lamp is at the point labelled zero, and Jack is 4 units away. To see the lamp two times larger than Jack does, how far from the lamp should one be? (2 pt.)

2. Refer to the same figure as in the previous question. To see the lamp four times dimmer than Jack does, how far from the lamp should one be? (2 pt.)

3. Pairs of stars that can be seen to orbit each other on are called (2 pt.)

4. Binary systems in which one member of the pair of orbiting stars blocks light from the other are called





5. A solar-mass main sequence star in a binary system can eventually be observed as (2 pt.)

6. By studying blackbody curves from one hot and one cold object, one knows (2 pt.)

7. Which of the following astronomers believed the heliocentric hypothesis? (Circle all that apply. 4 pt.)

8. What can be said of stars of spectral class B? (Circle all that apply. 4 pt.)

9. Conservation of angular momentum predicts (Circle all that apply. 4 pt.)

10. What properties would enhance an extrasolar planet's chances of being discovered from radial velocity fluctuations? (Circle all that apply. 4 pt.)


V. Problems.

1. The galaxy at left below rotates clockwise from your perspective. The observer at right analyzes light from four different parts of the galaxy, each shown with a box. Answer the questions below the figure by writing in the appropriate number(s) in the blanks. (10 pt.)


a) List the redshifted part(s) of the galaxy, compared to other parts. _____

b) List the part(s) exhibiting neither red nor blue shifts compared to other parts. _____

c) Of the parts approaching the viewer, which would Kepler predict to be orbiting more slowly, based upon the amount of visible matter? _____

d) Would the observer actually measure this part orbiting more slowly? Circle one: YES or NO.

e) Provide a short (1-5 word) answer: What do astronomers believe causes the difference between Kepler's prediction and what the observer measures?




2. Absolute magnitude is a star's brightness at a distance of 10 pc from the star. In the table's third column, state whether the star is closer or farther than 10 pc. (2 pt.)
Apparent Mag.
+ 5.0
+ 3.4
0.0
+11.1
Absolute Mag.
+ 7.0
- 1.4
+ 2.1
- 5.6
closer/farther






3. Mindless Regurgitation of Facts:
a) List the planets, in order of increasing distance from Sun. (5 pt.)



















b) Name four types of EM radiation. Write the four you choose to list in order from highest to lowest energies. (4 pt.)








4. Give two arguments (2-10 words each) for believing the Earth is spherical, as opposed to flat. (4 pt.)
a)






b)









5. Three observers see spectra (using prisms) along three different lines of sight, as pictured schematically below. (4 pt.)

Which observer sees which spectrum?

A) _____; B) _____; C) _____

Spectrum #1 is an ____________ spectrum.

Spectrum #2 is an ____________ spectrum.









6. Hertzprung-Russell (H-R) Diagram:

a) On the balnk plot below, choose appropriate labels for the axes as they could appear on an H-R diagram, and indicate the direction of increase for each, if appropriate. (2 pt.)

b) Name another label you could use for each axis: (2 pt.)

c) On the plot, sketch in where white dwarfs, the giants, and the main sequence fall. (3 pt.)

d) Label the approximate current location of the Sun on the diagram. (1 pt.)




BONUS: What is the moon's phase now? (3 pt.)