Use these questions to test your understanding of the material for the second
exam. If you get them wrong, you will be linked back to the relevant part of the notes. Be
sure you study them thoroughly (don't just get a quick fix for your mistake) so your
overall understanding is improved.
Review the questions for the other hourly exams and for the final.
1. These days, astronomers depend on ____________ for obtaining new observations of photons from the stars
a. their eyes b. refracting telescopes c. electronic detectors d. discovering notebooks of previous astronomers
2. Astronomers like big telescopes because
a. big telescopes make them feel important
b. big telescopes can see smaller details (have higher resolution)
c. they actually prefer small ones because they are easier to move around
d. big telescopes can carry heavier instruments than small ones
3. Observatories are put in in space
a. to get them closer to the stars
b. so they can observe night and day
c. because they can be pointed more accurately there
d. to get above bad weather so observations are not interrupted by clouds
e. to get above the atmosphere and its absorption of photons
4. Gravity is an important force in shaping the Universe because
a. it is the strongest force we know
b. it works well over long distances and there is no antigravity
c. actually, it does not play much of a role off the surface of the earth
d. it holds the protons and neutrons in the nucleus of an atom
e. it is the only inverse r squared force
5. The "strong nuclear force"
a. affects the motions of the planets because it is the strongest force
b. is actually the second strongest force
c. has little direct effect on the motions of the planets because it is so short range
d. holds the electrons in orbit around the atom nucleus
e. holds atoms together to make large objects like planets
6. "anti matter"
a. is repelled by the gravitational field of the earth
b. is a prediction of physics that has not been found yet
c. is the material some of the other planets might be made of
e. is an invention in science fiction stories
7. The most basic building blocks of matter that we know about are
a. protons, neutrons, and electrons b. photons c. quarks d. antiprotons and antineutrons e. neutrinos
8. The electromagnetic force does not dominate interactions between celestial bodies because
a. it is too weak b. it acts only over short distances c. it needs magnetic materials to be effective
d. positive charges largely cancel the effects of negative ones e. actually, it does dominate such interactions
9. An "open" universe is
a. one that will expand forever
b. one that galaxies can escape from, to enter other universes
c. one with a hole in it
d. one we can see out of to glimpse other worlds
e. one with critical mass
10. The Universe is
a. open
b. closed
c. at the critical density between open and closed
d. oscillating
e. articulating
11. What came before the Big Bang is
a. described by subnuclear physics
b. a vexing philosophical question for science, as for religion and other disciplines of thought
c. another Universe
d. revealed in our understanding of the Planck era
e. a sea of quarks that formed the raw material for the Universe
12. We will eventually be able to locate where the Big Bang occurred
a. by accurate measurements of galaxy velocities and distances
b. by measuring the redshifts of very distant quasars
c. using gravitational lenses
d. by measuring anisotropies on the cosmic background radiation
e. none of the above
13. How does the average density of the Universe affect its predicted fate?
a. it makes no difference
b. if the Universe has a high density, its expansion is expected to reverse and it will collapse
c. if the Universe has a high density, it will eventually form many more galaxies than now
d. a high density Universe will have many more stellar collisions
e. if the density is too high, the Universe will form too many heavy elements
14. The cosmic background was discovered
a. as a faint noise component in the microwave spectral region
b. with the 100-inch telescope
c. by infrared space missions
d. as noise that interfered with TV broadcasts
e. in early efforts to detect other civilizations
15. One of the reasons the sky is dark at night is
a. we are in a dark part of the Milky Way
b. there is a lot of dark matter out there
c. the Universe is expanding
d. dust blocks our view in almost every direction
e. we look up, out of the Milky Way when the earth turns us away from the sun
16. If new measurements showed that the currently adopted value if Hubble's constant is two times too small, then we could conclude that the age of the Universe
a. was twice what we had believed before
b. was the same as we had believed before
c. was half what we had believed before
d. was four times what we had believed before
e. had changed but by an amount we could not estimate
17. The assumption that the Universe is homogeneous on very large scales is
d. the theory of equipartition
18. Hubble's Law implies that
d. the other galaxies were shot from the Milky Way
e. the Universe is not uniform
19. To a physicist studying the early Universe, unification is
a. a political movement to discredit unpopular theories
b. the concept that the fundamental forces of physics unified under extreme conditions
c. a theory combining aspects of biology and physics
d. a merger of observational and theoretical results to get a consistent picture of the early Universe
e. a process for combining different theories in a computer code
20. The period of very rapid inflation in the early Universe solves the mystery of
a. why the Universe is so uniform
b. why the Universe is expanding
c. why balloons are sometimes used to illustrate the expansion
d. why there is so much empty space
e. how the ratio of hydrogen to helium is what it is
21. Understanding how subatomic particles like quarks behave is critical to understanding
a. why the cosmic background radiation is so uniform
b. the fate of Earth in the cosmos
c. conditions in the early Universe
d. why the cosmic background is in the microwave wave spectral region
e. the structure on the cosmic background
22. The "flatness problem" refers to
a. why space-time is not curved
b. how the Universe came out just at the density that balances its gravity
c. how spiral galaxies can maintain such flat disks
d. the extreme uniformity of the cosmic background radiation
e. why we do not see peaks in mass due to matter coming from other Universes
23. You are made of
a. antimatter
b. nonbaryonic matter
c. baryonic matter
d. neutrinos
e. neutral matter
24. We know that the Universe is only about 6% protons and neutrons - baryons - because
a. if there were more, the Universe would be closed
b. fusion reactions would have produced more lithium and maybe heavier elements if there had been more baryons
c. we don't really know this
d. because the things around us are made of 6% baryons
e. from measuring the properties of dark matter
25. The 3 degree cosmic background radiation originated when
a. the Universe got started in the Big Bang
b. the first stars began radiating
c. active galactic nuclei heated up interstellar dust
d. electrons were captured by protons to make the Universe transparent
e. inflation occurred
26. The contrast in the structure on the 3K cosmic background tells us about
a. what kind of matter formed (fraction of baryonic or nonbaryonic)
b. where the first galaxies are
c. irregularities in the Big Bang
d. how the fundamental forces decoupled
e. where the cold spots are in the Universe
27. Dark matter a. does not really exist
c. played a critical role in the merger of galaxies in the early Universe
d. no longer exists in significant quantities
e. glows faintly, allowing it to be observed with modern space telescopes
28. The early stages of development of the Universe a. are surprisingly well understood through a combination of physics and astronomy
b. are really hard to study because conditions were so extreme
d. may have been either steady state or big bang in nature
e. were a time when a totally different physics operated
29. The cosmic background radiation provides strong evidence that
a. the early Universe was very cold, only 3 degrees above absolute zero
b. stars formed almost immediately in the early Universe
c. the Universe has been expanding steadily forever
d. the Universe evolved from a hot, dense state
e. a lot of energy was produced through hydrogen fusion early in the life of the Universe
30. The cosmic background radiation is visible equally in every direction because
a. we are at the center of the Universe
b. we are not moving fast enough to Doppler shift the background by a large amount
c. we are looking back to when the Universe was young and opaque in every direction
d. the background has been scattered many times and now looks uniform
e. our telescopes are just not powerful enough to see far enough away to detect the nonuniformities
31. Astronomers cannot look back further than when the Universe was 300,000 to 500,000 years
old because
a. before that, the Universe was too crowded with stars
b. photons were not produced until the Universe was 300,000 years old
c. dust in the early Universe absorbed the light
d. the Universe was made of dense, ionized gas that was opaque to light
e. our telescopes are not yet big enough to see that far
32. The granules visible on the Sun's surface are evidence of
a. large amounts of iron b. magnetic storms c. convection d. gas escaping into space
e. electromagnetic radiation from the Sun
33. The Sun's corona has a temperature of more than a million degrees. What wavelength regime would be most useful for studying the corona?
a. visible light b. radio waves c. infrared light d. x-rays e. long wavelengths
34. The term "solar cycle" refers to
a. periodic changes in the Sun's brightness b. the 22 year pattern in sunspots and magnetic field direction
c. a solar-powered bicycle d. the length of time it takes the Sun to orbit the center of the Milky Way
35. The major constituents of the Sun are
a. iron and nickel b. hydrogen and helium c. oxygen and carbon d. water and salt e. neon and krypton gas
36. The danger to astronauts from solar flares and coronal mass ejections is greatest when
a. Sun is at a sunspot maximum b. the magnetic field is least tangled
c. more granules are formed d. Sun rotates faster
e. danger is the same all the time
37. The underlying cause of the solar cycle is
a. winding up of the sun's magnetic field due to differential rotation
b. oscillations in the center of the sun
c. changes in the temperature of the sun
d. the sunspots appear at different latitudes on the sun
e. changes in the rate of coronal mass ejections
38. Sunspots are
a. regions where strong absorption lines reduce the output of the sun
b. regions where a strong magnetic dipole interferes with the outward transport of energy
c. bodies above the surface of the sun that block some of its light
d. where cool bodies have recently fallen into the sun
e. where solar storms bring cooling flows
39. The Sun has been able to produce energy for billions of years by
a. a chemical process similar to burning coal b. gravitational contraction c. absorbing light from distant stars
d. nuclear fusion e. none of the above
40. The Sun's output is so stable because
a. pressure of Sun's gas just balances gravitational contraction
c. the Sun doesn't produce much energy
e. the Sun has only small sunspots
41. Although deep inside the sun, energy is carried by photon streaming, energy is carried to the surface of the sun
c. by convection, like boiling
42. If we have a container of hydrogen gas sitting in a laboratory on Earth, why doesn't it turn into helium?
a. because trace elements are required b. because the temperature and pressure are too low
c. because the hydrogen needs other isotopes d. because an electric spark is needed
e. it will become helium if you wait long enough
43. Hydrogen fusion can produce energy because
b. the atoms join together into bigger molecules, and the molecular binding energy is released
d. the helium that is produced has been heated to very high temperature
e. the high pressure where the fusion takes place yields some of its energy
44. If the earth were further from the Sun than it actually is, the parallax angle for stars would be
a. larger b. smaller c. the same
45. Which two things are needed to determine an object's distance from the Earth if it is too distant to use trigonometric parallaxes?
a. velocity and luminosity b. velocity and apparent brightness
c. apparent brightness and luminosity d. apparent brightness and size
46. Two stars, X and Y, have the same luminosity but star X is a very blue star while Y is a red star. Which star has the larger radius?
a. Star X b. Star Y c. Not enough information has been provided to choose.
47. You are living 200 years ago and want to discover parallax. Your best bet is to choose
a. bright stars b. dim stars c. stars with large proper motions d. stars with small proper motions
48. The sequence of spectral types that Miss Cannon discovered is actually a sequence
a. of percentage of hydrogen in a star b. of velocity through space c. of apparent magnitudes
d. of temperatures e. of numbers of sunspots
49. If you want to measure the mass of a star, you must
a. look for a pair of stars orbiting each other b. use Kepler's 3rd Law c. measure the star's temperature
d. measure the star's radius e. do both a and b
50 To measure the luminosity of the sun from the earth, we need to measure
a. Earth's distance from the sum
b. the flux Earth receives from the sun (the apparent brightness of the sun at the earth)
51. In the figure above, which star has the largest surface area?
52. Which one has the smallest surface area?
53. The basic properties that control the current status of a star are
a. age, mass, initial composition b. temperature, distance, color
c. spectral type, composition, temperature d. distance, magnitude, color
54. A star will become a red giant when
a. it begins to convert H to He b. when its composition changes
c. when it can no longer convert H to He in its core d. when it gains mass
55. A star may be a variable star because
a. it alternately expands and contracts b. planets fall into it and block the light
c. it makes more or less dust d. its mass changes
56. The oldest stars are most likely to be
a. the brightest stars b. the most massive stars c. the hottest stars
d. the least massive stars e. the stars with largest percentage of hydrogen
57. The lower limit on the size of a star is set by
a. the size of cloud fragment that can form b. the gravitational field of a cloud
c. the amount of H that can coalesce d. the mass require to get the core hot enough for conversion of H to He
58. Two stars both have spectral type A. One has a luminosity that is 1000 times larger than the other. What parameter differs the most between these two stars?
a. temperature b. color c. radius d. composition e. distance
59. The upper limit on the size of a star is set by
a. the size of cloud fragment that can form b. the gravitational field of a cloud
c. the stability against photon pressure d. the mass require to get the core hot enough for conversion of Si to Fe
Here are the properties of three main sequence stars: 1.)Barnard's Star T= 3370° K L=0.005 LSun ; 2.) Sun T= 5800° K L = 1 LSun
3.) Spica T=26,000° K L = 23,000 LSun
60. List these stars in order of increasing mass.
a. Spica, Sun, Barnard's Star b. Spica, Barnard's Star, Sun c. Barnard's Star, Sun, Spica
d. Barnard Star's, Spica, Sun e. Sun, Barnard's Star, Spica
61. Under what circumstances can a star convert oxygen to silicon?
a. when it makes dust in its outer layers
b. when it reaches the main sequence
c. when it becomes a white dwarf
d. when it becomes a black hole
e. when the core of a massive star gets hot enough
62. A white dwarf does not collapse further because
a. it is converting H to He b. it is converting He to C
c. its electrons can't be squeezed together any more d. it is made of dark matter
63. Pulsars vary their light output by
a. alternately expanding and contracting b. alternately heating up and cooling off
c. sweeping a light beam across our line of sight d. converting H to He
64. Planetary nebulae are
a. in the process of forming planets b. molecular clouds
c. the ejected outer layers of a dying star d. the precursors to black holes
e. the result of protostars having disks
65. A neutron star is mostly neutrons because
a. the protons it used to contain have collected into a proton star
b. it has a proton core, but neutrons cover the surface
c. the huge pressure has caused its electrons to merge with its protons to make neutrons
d. antiprotons have annihilated all the protons it used to contain
e. the protons have collapsed into a black hole in its core
66. If you add mass to a white dwarf to "bulk it up" above 1.4 solar masses,
a. it will get smaller and smaller and finally collapse into a neutron star
b. it will develop strong coronal lines because of its high surface temperature
c. it will increase in radius in proportion to the cube root of the additional mass
d. the new matter will cause it to cool on the surface and get fainter
e. the matter will disappear beyond its event horizon and we will not know what happens
67. The most important aspect (to us) of the material ejected by dying stars is
a. it makes beautiful nebulae that inspire our interest in astronomy
b. it shields us from dangerous radiation emitted by the dying star itself
c. it reduces the mass of the star so its end is less violent
d. we are made of material ejected by dying stars a long time ago
e. it causes interstellar extinction
The next five questions refer to the following graph.
68. Which letter indicates where giant stars would be found in the HR diagram?
69. Which indicates the location of white dwarfs?
70. Which indicates where spectral type would be found?
71. Which indicates the location of the main sequence?
72. Which indicates where luminosity would be found?
73. What is the closest location for finding material formed in a supernova explosion?
a. the Milky Way b. the Orion nebula c. the Crab Nebula d. the Sun e. your own body
74. A remarkable observation from the 1987A supernova was
a. the detection of gravity waves b. the detection of neutrinos
c. the detection of a pulsar d. the detection of a black hole
75. We know that the Crab nebula is a supernova remnant because
a. it contains a pulsar b. Chinese astronomers witnessed the explosion c. it emits lots of x-rays
d. its gas is moving very rapidly e. all of the above
76. The Crab Nebula pulsar is spinning
e. at a rate determined by its mass
77. The cooling rate in SN 1987A showed that
a. it was full of very hot gas that could not lose energy efficiently
b. it contained huge amounts of cobalt
c. a massive star was still powering things in its core
d. it was really a type 1 supernova
e. not all the neutrinos escaped quickly
78. If you took spectra of a supernova remnant, you would see
a. only H and He b. many elements such as O, C, Si c. only cool gas
d. only dust e. both c. and d.
79. The elements like oxygen and iron in the earth got there because
a. they were swept up as the early sun went through a region with lots of these elements
c. they were created in the early stages of the Big Bang
e. they were pulled from a passing star by the sun's gravitational field
80. Radio telescopes are very large compared to telescopes for visible light because
a. sources emitting radio waves are very dim
b. because radio waves are much longer than visible light ones
c. because eyepieces work poorly at radio wavelengths
d. because radio astronomers are better at getting funding for their telescopes
81. Star A has a parallax of 0.5" while Star B has a parallax of 0.15".
a. Star A is closer than Star B. b. Star A is 2 parsecs away.
c. Star B is closer than Star A. d. Both a. and b. are correct.
e. More information is needed to know anything about these stars.
82. The "Big Bang" model of the Universe was confirmed when we
b. detected the 3K light left over and redshifted to its very low temperature
c. discovered the expansion of the Universe
d. saw a blinding light toward where the explosion occurred
e. detected X-rays from the hot gas in the explosion
83. Most of the helium was made
a. in the first generation of massive stars
b. in thermonuclear reactions in supernova explosions
c. in thermonuclear reactions in the first few minutes of the Universe
d. the helium was there from the beginning
e. we do not understand where all the helium came from
84. Grand unified theories suggest that, at extremely high temperature and pressure,
a. all the forces of physics can be explained in a single physical law
b. all the elements are unified into a single type of matter
c. fundamental particles like quarks unify into protons and neutrons
e. matter falls into a black hole
85. The low luminosity stars on the main sequence
a. are the hottest b. have the shortest lifetimes
c. are the coolest d. have the most helium
86. The Sun will end its life as
a. a neutron star b. a pulsarc. a black hole d. a brown dwarf
87. Observational proof that neutron stars exist is provided by
a. black holes b. hot stars c. pulsars d. cool stars e. planetary nebulae
88. The escape velocity at a black hole's event horizon is
a. the same as from the earth b. the speed of light
c. the same as from the Sun d. different for different elementary particles
e. highly dependent on the black hole's characteristics
89. Proof of Einstein's theory of how gravity can affect light is given by
a. the size of the Earth b. the rate at which stars produce energy
c. the bending of star light near the limb of the Sun d. the speed of light
e. the existence of white dwarfs
90. Heavy elements like silver and gold are formed
a. on planetary surfaces b. in planetary nebulae
c. in main sequence stars d. in supernova explosions
91. Stars on the main sequence all
a. are in hydrostatic equilibrium b. have the same mass
c. have the same temperature d. have the same diameter
e. there is no property in common among main sequence stars
92. The diagram above shows the evolutionary track of a star
like the Sun after it leaves the main sequence. At Point A, the star is
a. burning hydrogen in its core and helium in a shell
b. burning hydrogen in a shell around a collapsing core
d. burning hydrogen in its core
93. At Point C, the star is
a. burning hydrogen in its core and helium in a shell
b. burning hydrogen in a shell around a collapsing core
d. burning hydrogen in its core
94. At Point B the star is
a. burning hydrogen in its core and helium in a shell
b. burning hydrogen in a shell around a collapsing core