1. When astronomers look at distant galaxies, what sort of motion do they see?
A) The Galaxies are all spinning rapidly.
B) The galaxies are all moving rapidly toward us.
C The galaxies are all moving rapidly away from us.
D) Galaxies are falling toward three centers in opposite parts of the sky.
E) Galaxies to our north are moving away from us. Those to our south are approaching.

2. How do astronomers detect this motion?
A) The shift in spectrum lines of the galaxies.
B) The steady dimming of the galaxy's light.
C) The rapid brightening of the galaxy's light.
D) The disappearance of the most distant galaxies, one by one..
E) The sudden appearance of new galaxies where none was previous seen..

3. What is meant by the redshift?
A) The galaxies are growing redder as we watch.
B) The galaxies are cooling off.
C) The spectrum lines of the galaxies are shifted to redder wavelengths.
D) None of the above
E) Only A and B

4. What do astronomers infer from the motion of the distant galaxies?
A) The Universe is contracting.
B) The Universe is expanding.
C) The Universe is imploding.
D) The Universe is spinning..
E) None of the above.

5. Astronomers have found the cosmic microwave background (CMB) radiation. What is the nature of this radiation?
A) It is a bright, uniform, x-ray glow.
B) It is a a faint, uniform, radio signal.
C) It is a a faint, uniform, x-ray glow.
D) It is a weak and very patchy glow at visible wavelengths.
E) It is a weak background of cosmic neutrinos.

6. About what temperature does the CMB have at this time?
A) 30 million K.
B) 3 trillion K
C) 2 billion K
D) 3000K
E) 3 K.

7. How was the CMB created?
A) The fusion of H into He by the first stars.
B) The radioactive decay of uranium.
C) The formation of quarks in the big bang.
D) The burst of radiation from the big bang as it cooled toward 10,000 K..
E) The combined effect of billions of distant quasars..

8. Why is the CMB so cool now?
A) The expansion of the Universe has cooled the radiation and stretched its wavelengths.
B) Dense clouds of dust have blocked most of it.
C) The cosmological constant has "squashed" its wavelengths and cooled it.
D) Hydrogen atoms have condensed on it and chilled it.
E) None of the above

9. The sketch above shows the velocity and distance of a few galaxies. The curve turns down on the right. This shows that
A) The Universe is contracting.
B) The Universe is expanding faster now than in the past.
C) ) The Universe is expanding slower now than in the past..
D) The Universe is younger than we think..
E) None of the above.

10. What effect do astronomers think causes this turn-down?
A) The cosmological constant is forcing space to expand faster now than in the past.
B) Large amounts of dark matter are slowing the expansion of space.
C) The CMB is exerting a radiation pressure on space and speeding its expansion up.
D) Gravity is pulling galaxies toward the Universe's edge.
E) The gas pressure of dark matter is pushinh space outward ever faster.

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