Final Exam Answers
ASTRONOMY 123
Final Exam
Answers
1. The Urey-Miller experiment simulated
e. the evolution of complex molecules on the primitive Earth
2. Extrasolar planets have been detected by
a. the wobble of the associated star
3. The part of the radio spectrum considered best for searching for extraterrestrial
intelligence is called
a. the "water hole"
4. A closed universe is
d. finite and unbounded
5. A rare form of galaxy is
a. an active galaxy
6. The globular clusters of the galaxy are located primarily in the
b. halo of the galaxy
7. When the globular clusters were formed, the Milky Way was
b. a large sphere of at least 100,000 light years diameter
8. What radiation travels faster than visible light?
a. radio waves
b. gamma rays
c. neutrino rays
d. X-rays
---> e. none of the above
9. Collisions between galaxies:
c. may cause bursts of star formation
10. What is a supercluster?
b. A cluster of clusters of galaxies
11. The cosmic microwave background radiation was discovered
a. with a low-noise radio antenna
12. The present temperature of the cosmic microwave background radiation is
a. 2.7 K
13. Which of the following futures is not possible for a Big Bang universe?
d. Steady state
14. When Penzias and Wilson examined their signal of static, they
discovered all of the following, except.
d. Found the signal matched the pattern of active galaxies
15. The cosmic microwave background radiation we observe on Earth now
b. has traveled for more than ten billion years.
16. What was Einstein’s “fudge factor?”
d. cosmological constant
17. What theory explains the curvature of space due to mass/energy?
e. Einstein's General Theory of Relativity
18. Which of the following is visible by the naked eye from the earth?
b. The Andromeda galaxy
19. The fossil record shows existence of life on Earth dating back
b. billions of years
20. Two-way communication with a civilization 100 light years away will require at least
d. 200 years.
21. Regions of the universe now separated by very large distances appeared
with the same temperature in the early universe. This is known as
d. the horizon problem.
22. The variations in a Seyfert galaxy's luminosity over a year or so shows
its region of emission is
a. not very large.
23. Variable stars are useful as standard candles because of the close
relationship between
a. period of pulsation and luminosity.
24. What was the subject of the famous Shapley-Curtis debate?
d. The nature and distance of spiral nebulae
25. What is the approximate fraction of the critical density represented by
normal matter?
a. 0.05
26. What might arise from vacuum energy?
b. A cosmological constant
27. What fraction of the universe’s composition today is dark energy?
d. about 70 percent
28. What do we learn from analysis of Planck data?
a. Age of the universe
b. Total energy-mass density (Ω0)
c. Fractions of ordinary matter, dark matter, and dark energy
---> d. All of the above
29. The first evidence of dark energy came from
a. measurements of distant supernovae.
30. Dark energy is responsible for
b. an accelerating expansion of the universe.
31. Geometry of the universe if the density of matter/energy is less than the critical density:
b. open universe
32. The bullet cluster is an example of
c. the collision of two galaxy clusters.
33. The Very Large Array in New Mexico
d. detects radio emissions.
34. The mass of the Milky Way Galaxy, in units of solar mass, is nearest to
d. 1012
35. A general rule of stars is
d. the lower the metal abundance, the farther objects appear
from the galactic disk.
36. Assumed property of the universe which says the number of galaxies in a
volume of space is the same no matter where that volume is
d. homogeneous.
37. Mass in galaxies and clusters inferred from rotation curves and other techniques
b. dark matter
38. Geometry of the universe if the density of matter/energy is greater than the critical density:
a. closed universe
39. The 1974 message sent from Arecibo consisted of 1679 bits of information.
Why was this number of bits chosen?
b. 1679 = 23 x 73, two prime numbers.
40. Two sources of energy for chemical reactions available on the young Earth
were
a. lightning and volcanism.
41. The flatness problem is solved by
a. inflation.
42. What is a gravitational lens?
b. light is bent by matter and energy
43. The number of stars in the Milky Way Galaxy is thought to be nearest
d. 1011
44. The main difference between an Sa galaxy and an Sc galaxy is
d. the Sa galaxy has a larger central bulge.
45. What does the Hubble Law measure?
a. The rate of expansion of the universe.
46. Hot dark matter consists of
a. light particles such as neutrinos.
47. If the early universe differed slightly from the critical density it
would now differ greatly. This is known as
c. the flatness problem.
48. When the energy of photons was converted to matter and anti-matter in
the very early universe
a. matter and anti-matter were initially created equally.
49. The radiation era ended and the matter era began about ________ after
the Big Bang started.
c. 50,000 years
50. The largest objects seen in the universe are
a. radio galaxies.
51. Seyfert galaxies are characterized by
b. bright nuclei.
52. The rotation curve of our galaxy supports the thesis that
d. more than 80% of the mass of our galaxy is dark matter.
53. The nucleus of Helium-4 (the most common form of helium) is composed of
c. 2 protons and 2 neutrons.
54. Most of the fusion of the nuclear epoch occurred during the first
____________ of the Big Bang.
b. 20 minutes
55. The spurt of growth in the size of the universe occurred during
c. inflation.
56. Inflation occurred within __________ of the Big Bang.
a. 10-35 seconds
57. The Magellanic Clouds are
d. irregular galaxies.
58. Which of the following is NOT an active galaxy
d. M31
59. Spiral arms appear prominently in the images of spiral galaxies because
d. hot stars in the disk are distributed in a spiral pattern while
the cool stars are spread more uniformly.
60. Cold dark matter consists of
c. heavy particles.
61. The horizon problem is solved by
a. inflation.
62. Astrophysicists have tried to explain spiral arm formation with
a. the density wave theory.
c. the supernova chain reaction theory.
---> d. both a and c
63. What is the definition of redshift?
d. (observed wavelength - true wavelength ) / true wavelength
64. In a lobe radio galaxy, the radio emission primarily comes from
c. enormous extensions of the galaxy that dwarf the optical galaxy.
65. Galaxies which appear like normal spirals, but with a very bright
galactic center are
a. Seyfert galaxies.
66. The temperature fluctuations on the microwave background are found to be
c. a few parts per 100,000.
67. The first density fluctuations in the universe probably occurred in
a. the dark matter.
68. The best wavelength of the electromagnetic spectrum for searching for
extraterrestrial intelligence is thought to be
c. near the 21-cm line of hydrogen.
69. Which of the following is not part of the Drake equation?
b. Rate of molecular evaporation
70. Pair production can create which of the following pairs?
d. an electron and a positron
71. What leads us to conclude quasars are relatively small?
a. rapid variability of radiation output
72. Identify M31 from the following list:
d. The Andromeda Galaxy
73. The look-back times for quasars are
c. very large.
74. Which of the following is NOT a part of the central engine of an active
galaxy?
a. globular cluster
75. The fluctuations in the microwave background were discovered by
a. COBE.
76. Studies of distant supernovae suggest
b. the expansion of the universe is accelerating.
77. Images of young, background galaxies, warped by the gravitational field
of a foreground galaxy cluster are
c. blue arcs.
78. What causes the small asymmetry in the cosmic microwave background?
d. Earth's motion through space
79. Assumed property of the universe which says it is the same in all directions:
c. isotropic
80. A galaxy left alone will evolve slowly, in a predictable way.
b. Spirals will remain bluish as long as there is new star formation
81. The concept that galaxies grew through repeated merging of smaller objects is
d. hierarchical merging.
82. The distance from Earth to the Great Wall is
d. about 100,000,000 pc.
83. The search for extrasolar planets is biased toward
d. large planets orbiting close to a star..
84. The present-day universe is composed of
b. much more matter than anti-matter.
85. A technological civilization would probably "announce" itself to the
universe through
a. radio & television signals.
86. The Cosmological Assumptions include all of the following except
c. The universe is infinite
87. Which of the following is an observed property of the cosmic microwave
background radiation?
e. Its spectrum matches a blackbody spectrum
88. We know the "center" of the universe from
e. the concept of "center" of the universe does not exist
in our modern view.
89. The present day universe is now thought to be
e. dark energy dominated.
90. Star formation in the Milky Way occurs primarily today
d. in the disk.
91. What era was the universe in during galaxy formation?
a. Matter era
92. All of the hydrogen of the universe and most of the helium observed today
were created by
b. primordial nucleosynthesis.
93. Which of the following is favored as the dominant form of matter in the universe?
e. Cold dark matter
94. Which of the following is not an active galaxy?
d. Milky Way
95. A quasar with a red shift of 2 would be at which of the following look-back times?
e. 10,000,000,000 years
96. The spectrum of light coming from normal galaxies is characterized by
c. the sum of many blackbody spectra.
97. The observations of the universe led to the following conclusion:
a. the universe will expand forever.
98. Which of the follow galaxies has the least intergalactic matter (dust and gas)?
b. elliptical galaxies
99. Which of the following is a true statement?
e. The Andromeda Galaxy is approaching the Milky Way, and is
expected to eventually collide with the Milky Way.
100. What is an effective way to map out the spiral structure of the Milky Way?
d. measure the distribution of HI through the 21 cm line.