Use these questions to test your understanding of the material for the third
exam. If you get them wrong, you will be linked back to the relevant part of the notes. Use these questions to test your understanding of the material for the third
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 final.
1. We know about the black hole in the Galactic Center because
a. It glows brightly
b. Shapley found it
c. from Newton's and Kepler's laws
d. because we see a dark spot where it bends the light away
e. because we have seen things get sucked into it
2. When matter falls into a black hole
a. it quickly disappears from sight
b. great amounts of energy can be released
c. it passes out into another Universe
d. it takes an unfamiliar form
e. its light shifts to the blue
3. Superluminal - faster than light - motions result when
a. the geometry of motions sets up an optical illusion
b. matter falls into a black hole
c. there is such a violent explosion that pieces are expelled faster than light
d. Einstein's laws are broken
e. neutrinos are accelerated to a very high speed
4. The nature of quasars was initially confusing because
a. their emission lines were at peculiar wavelengths
b. they were radio sources
c. they varied rapidly
d. they were very luminous
e. they looked like stars
5. An active nucleus can be identified by
a. bright and broad emission lines
b. radio jets emerging from the nucleus
c. a bright source that varies rapidly
d. strong X-ray emission
e. all of the above
6. Active galaxy nuclei are powered by
a. matter falling into a very massive black hole
b. lots of star formation
c. energy left over from when the galaxy formed
d. radio jets extending out into space
e. galaxy mergers
7. Jets emerging from an active nucleus contain particles moving nearly at the speed of light because
a. that is the only way to account for their apparent superluminal motions
b. that is how they can get so far from the galaxy
c. we measure extreme Doppler shifts in their emission lines
d. it accounts for their prominence in the radio region
e. both a. and d.
8. A good way to look for a massive black hole in the nucleus of a galaxy is to look for
a. a dark spot projected against the starlight of the galaxy
b. a tight knot of stars being sucked into the gravitational field of the black hole
c. lensing of background galaxies behind the nucleus
d. distortions in the shape of the galaxy due to the large gravitational field
e. very large Doppler shifts in the spectra of stars close to the center of the galaxy
9. The rapid variability in the outputs of quasars and other active nuclei shows that
c. the nuclear sources are very small
d. stars are blowing up in these regions
e. the apparent variability is an effect of gravitational lensing
10. The clearest evidence that quasars are at great distance is
b. that they lie in the centers of galaxies that are at large distances
c. that their emission lines are shifted to the red
e. the faintness of the Cepheid variables in them
11. We know about dark matter
a. because it blocks our view in certain directions
b. because it can be seen in other galaxies but not in the Milky Way
c. because black holes left by massive stars are sometimes visible in the X-ray
d. from the rotation curves of galaxies that show mass outside the region of stars
e. because the planets seem to orbit the sun faster than the mass of the sun alone would require
12. Why does the rotation curve of a galaxy increase with increasing distance near the galaxy's center?
a. the encircled mass increases so fast that gravity increases with radius
b. the stars are exploding outwards from the center, thus showing the high speeds
c. most of a galaxy's mass is in the center
d. because the center rotates like a rigid wheel or Merry-Go-Round
e. because of the effects of active galaxy nuclei
13. What is the evidence there is dark matter beyond the disks of spiral galaxies?
a. inner disk stars orbit faster than the mass due to stars and gas can explain
b. infrared telescopes detect mass beyond the galaxy disks
c. the stellar mass distribution does not account for the rotation curve of the galaxies
d. disk stars orbit faster than stars in the galactic centers
e. regions outside the disks obscure the light of galaxies behind them
14. The outer part of the rotation curve of a galaxy is flat; this fact indicates that
a. practically all the mass of the galaxy is within the radius where the curve flattens out
b. where the curve is flat, the encircled mass increases with increasing distance from the center
c. Newton's law of gravity is wrong
d. there is a supermassive black hole at the center of the galaxy
e. the galaxy is still in the process of forming
15. We think that either dark matter is in the form of low mass brown dwarfs and wandering planets, or, more likely
a. Newton's Law of gravitation is wrong
b. the Universe is filled with an undetected type of nuclear particle
c. the galaxy rotation curves are distorted
d. we are overestimating the accuracy of the velocity measurements in galaxies
e. the spectral lines suffer gravitational redshift due to Einstein's law of relativity
16. Spiral arms are prominent in some galaxies because
a. they mark where the dust is thin and we can see the stars better
b. they show where young and bright stars have formed
c. they represent bright blobs that have been wound into the spiral shape by the galaxy rotation
d. Population III stars make them bright
e. they mark where material has been ejected by the nucleus
17. The various types of galaxy
a. show a sequence that evolves with age from one to the other
b. include spirals, ellipticals, and irregulars
c. are a result of different distances to them and the resulting limits to the amount of detail we can see
d. are only apparent in the visible spectral range
e. show they are made of different types of matter
18. The Milky Way is a
a. barred spiral galaxy
b. elliptical galaxy
c. irregular galaxy
d. Sa galaxy
e. we do not have much idea of what type it is
19. What do we call the bright, roughly spherical, collection of old stars around the center of the Milky Way?
a. disk
b. halo
c. bulge
d. spiral arms
e. dark matter
20. Stars with high concentrations of elements heavier than hydrogen and helium
a. are likely to be very old
b. are found in globular clusters
c. are likely to have formed relatively recently
d. are members of population II
e. have very low mass
21. We see where the young stars are in a galaxy most easily when we look in
a. the visible and near infrared
b. the ultraviolet and far infrared
c. the X-ray and ultraviolet
d. the radio and gamma ray
e. the visible and X-ray
22. What do we call the faint, roughly spherical, collection of old stars around the entire Milky Way?
23. Galaxies are distributed
a. uniformly through space
b. in vast sheets and filaments that make a structure a little like soap bubbles
c. in clusters and groups
d. in rings around the Milky Way
e. both b. and c.
24. The mass of a cluster of galaxies
a. is entirely from its galaxy members
b. includes a significant part from very hot gas and even more from dark matter
c. results in broadening the spectral lines from active nuclei in the cluster
d. causes the cluster to glow all over as things fall into it
e. makes the emission lines of the galaxies in the cluster shift wavelength significantly due to relativity
25. Gravitational lensing
a. is being built in to the next generation of digital cameras
b. produces peculiar arc-like images of galaxies at high redshift behind massive galaxy clusters
c. is useful for studying planets that pass in front of the sun
d. was a surprise discovery not predicted by Einstein's theories of relativity
e. changes the color of the objects lensed
26. The large-scale distribution of the galaxies in space is a result of
a. the structure of the early Universe
b. galaxies of similar types tending to clump together
c. the gravitational attraction of great black holes that attract galaxies to their vicinity
27. Gravitational lenses in galaxy clusters are used
a. to search for distant planets
b. to study the theory of relativity
c. to improve our determination of Hubble's Law
d. to confirm that the clusters have huge amounts of dark matter
e. to get a better view of the Big Bang
28. The gas in an HI region is comprised of
a. hydrogen gas with electrons in the ground state b. ionized hydrogen gas
c. hydrogen iodide molecules d. x-ray emitting material
e. gas consisting of protons only
29. A molecular cloud is
a. a large, cold, dense collection of interstellar gas and dust
b. interstellar dust that is lit up by a nearby star and scatters some of the light toward us
c. an interstellar cloud made purely of complex molecules, mostly containing carbon
d. a region where a very hot star is ionizing the nearby gas
30. A newly formed massive, hot star changes the surrounding interstellar gas into
b. a glowing cloud of excited gas called an HII region
c. a dark globule seen as a shadow against the background light
31. Interstellar dust makes the things behind it look
d. it blots them out completely
32. A "reflection nebula" is
a. a cloud of interstellar grains aligned to reflect light similarly to a mirror
c. a cloud of interstellar material that lets look into regions we cannot see directly
d. an interstellar cloud that absorbs energy from nearby stars and emits it in the infrared
e. an interstellar cloud that is lit up by scattering light toward us from a star near the cloud
33. Why did astronomers in the 19th century believe that the solar system was close to the center of the Milky Way?
a. we are close to the center
b. they did not have photographic plates to detect very faint stars
c. their telescopes were too small to see the whole system
d. they needed infrared detectors
e. they did not realize how interstellar dust cut off their view
34. The Shapley-Curtis debate
a. was important philosophically because the topics touched on our place in the Universe
b. was decisively won by Shapley
c. was decisively won by Curtis
d. was an argument about the role of star formation in affecting our view of the cosmos
e. had to do with the superiority of Harvard College Observatory
35. That "spiral nebulae" were other galaxies like the Milky Way was first established when
a. we sent a spaceship to them
b. the new 100-inch telescope was used to resolve some of them into stars
c. from spectra that showed they had emission lines like the ones from the Milky Way
d. because they avoid the plane of the Milky Way
e. maps of the Milky Way in the HI line showed it to have spiral arms too
36. A "standard candle" for an astronomer is
a. a special candle of constant brightness maintained at the Bureau of Standards
b. an astronomical object whose luminosity can be determined independent of knowing its distance
c. a barred spiral galaxy
d. a votive candle of the usual size and wax content
e. a variable red supergiant star
37. Galaxy distances are important because
a. they let us calibrate parallax measurements
b. they help address the philosophical questions about our place in the Universe and how it is built
c. they show us which galaxies are coming toward us
d. they identify which galaxies are associated with each other in space
e. they tell us where to look to find stars with planetary systems
38. Henrietta Leavitt's period luminosity relation for RR Lyrae stars proved important because:
b. it was the first significant astronomical discovery by a woman
c. it explained why some star fields looked different in pictures taken at different times
e. it showed that they moved on the HR diagram
39. Galaxy distances are determined
a. just by using Cepheid variables
e. by a large variety of techniques that have to be used together, depending on the circumstances
40. Distance measurements to the galaxies around us show that
a. the Milky Way is isolated in space
b. the Milky Way belongs to a group of only three galaxies, including M31 and M33
c. the Milky Way is part of a galaxy group in which it and M31 are surrounded by many small galaxies
d. we are moving rapidly toward a certain point in space, leaving the nearby galaxies behind
41. The sun is located
a. in the outer part of the Milky Way's disk
b. in the halo of the Milky Way
c. near the center of the Milky Way
d. at an unknown location within the Milky Way
42. When galaxies collide
a. they explode
b. they pass right through each other with no other consequences
c. they tend to merge into a single galaxy
d. there is a loud noise
e. this happens so seldom we do not have a good idea of what happens
43. Galaxies undergoing starbursts
a. are full of bursting stars
b. are usually ellipticals
c. were identified through clusters of stars bursting out from them
d. are forming massive stars rapidly and in exceptionally large numbers
e. have less dark matter than other galaxies
44. Our own galaxy
a. is "safe" from colliding with other galaxies for the foreseeable future
b. is pulling apart some nearby galaxies and will eventually consume them
c. is being pulled apart by the Andromeda Galaxy
d. is highly distorted due to a very recent collision with a large galaxy
45. Spiral arms are
a. where the dust in a galaxy is thin enough that we can see the stars better
b. where stars from galaxies that have recently collided are spiraling into the center
d. the result of ejections from spinning black holes in galaxy nuclei
46. Galaxies can merge when
a. They fall into a black hole
b. They collide with each other and their stars combine into binaries
d. Their interstellar clouds join together to make a new galaxy
e. One of them accretes another.
47. Ring-shaped galaxies and galaxies with tails of stars are evidence for
a. galaxies forming from intergalactic matter
b. nuclear activity in galaxies
c. explosions across the face of previously normal galaxies
d. galaxies taking part in the expansion of the Universe
48. Star formation
a. occurs equally at all places in the disks of spiral galaxies
b. tends to be enhanced where peaks in the local density compress the molecular clouds
c. occurs wherever there is atomic hydrogen
d. occurs where halo stars collide with the disk
49. The best place to look for stars just beginning to form is
a. in empty space b. in a molecular cloud
50. Which physical force dominates the process of star formation?
a. strong nuclear b. weak nuclear c. electrical d. gravitational e. reactional
51. Disks form around young stars
a. if the cloud from which the star forms is too massive for all of it to fall into the star
b. when the new star passes through a dense cloud and it is attracted to the star
c. from material that was spinning around the protostellar core too fast to fall into the star
d. when a second star that formed in orbit breaks up
e. disks are something that only form around older stars
52. To form a real star, an object must be massive enough to
a. have enough gravity to hold planets in orbit
d. create enough pressure and heat in its core for hydrogen fusion
e. burn hydrogen and helium into heavier elements
53. Star formation is often aided by
a. planet passing through a molecular cloud and upsetting its equilibrium
b. a gravitational vibration caused by thermal instability in interstellar gas
c. a supernova explosion near a molecular cloud that compresses it and starts fragments collapsing
d. heating of an interstellar cloud by a nearby young star
e. centrifugal forces caused by spinning cloud fragments
54. A very large clump of interstellar matter
b. can make a star up to nearly any mass range
c. takes an extra-strong initial event to start it collapsing
d. collapses into a star particularly slowly because it is so big
e. can explode as a supernova rather than becoming a star
55. The planets in our solar system are thought to have come from
a. clumps of rocky material that exist between the stars
b. the same cloud of gas and dust in which the Sun formed
c. a cloud of gas in the Orion nebula
d. the Sun (they were flung out of the fast-spinning young sun)
56. As the solar nebula collapsed, it became a disk because
b. the initial cloud was disk shaped
c. the Sun's gravity pulled the nebula material into the ecliptic plane
d. the self-gravity of the nebula pulled the material into the ecliptic plane
57. The outer planets are mostly large and gaseous because
a. beyond the frost line, hydrogen froze to form the jovian planets
d. the disk's spin flung lighter materials farther from the Sun
58. Because of the temperatures in the protoplanetary disk,
a. rocks, metals, and ices (hydrogen compounds) froze in the inner region only
c. rocks and metals froze in the inner region only, and ices froze in the outer region only
59. As the solar nebula collapsed under its own gravity,
a. it heated and spun up b. it cooled and spun up
c. it cooled and spun down d. it heated and spun down
60. You are sent to find dense and rocky planets. Where in the Solar System should you look?
a. very far from the sun b. only in the middle
c. close to the sun d. in circular orbits
e. in regions with lots of moons
61. What kind of experiment has proven most useful for finding planets around other stars?
a. using a very large telescope to take pictures sensitive enough to capture their light
b. listening for radio emissions from civilizations on them
e. using spectrographs to measure absorption features associated with planetary atmospheres
62. A key characteristic of the cloud from which the Solar System formed was its
e. ability to have chemical reactions
63. In comparison with the black holes in some other galaxies, the one in the Galactic Center is curious because
b. it is harder to study in any detail
c. it seems to be making very little energy
d. it occasionally has a huge outburst
64. The Galactic Center was hidden from astronomers for many years because
a. it only emits in the radio and infrared
b. it is a very diffuse region that is hard to pinpoint
c. there were looking in the wrong places
d. the Milky Way has a peculiar, atypical structure that made it hard to find
e. it is hidden in the visible by clouds of interstellar dust
65. A black hole can glow in an active nucleus when
a. light escapes from within the event horizon
b. it lenses the light from objects behind it
c. friction heats matter falling into it to very high temperature
d. a pulsation in its gravitational field lets light out
e. it draws many stars into a tight knot around it
66. Most of the mass of the Milky Way is
b. in the supermassive black hole in its center
67. The discovery of large amounts of dark matter outside the visible diameter of galaxies is consistent with
a. the active nuclei arising from nuclear black holes
c. the presence of globular clusters in the halo of the Milky Way
d. ongoing star formation we see at the fringes of the Milky Way
e. the dimming of background galaxies near large, nearby galaxies like Andromeda
68. Galaxies come
a. in a chaotic, bewildering variety of shapes
b. always in the same shape - but they look different to us because we view them at different angles
c. in a limited number of shapes that we can describe in systematic ways
d. in different shapes depending on what kind of material makes them up
e. in different shapes depending on whether they have an active nucleus
69. In the Milky Way, most of the young stars are found in the
a. halo b. bulge c. bar d. disk e. tidal tails
70. We study galaxies at very high redshift to
a. see how far away we can see
b. determine how galaxies form and evolve to ones like ours
d. to see them smash into each other
e. to probe the earliest stages in the evolution of the Universe
71. The central galaxies of dense clusters are
a. similar to the other cluster members
b. massive spirals that attracted the rest of the cluster galaxies around them
c. virtually always with active nuclei because gas from the cluster is falling in
d. massive ellipticals that result from many mergers with smaller cluster members
e. galaxies with immense tidal tails and other indications of interactions
72. In very deep images that let us detect very distant and hence young galaxies, we find them to be
a. very similar to nearby ones
b. generally to be smaller and with less regular structure compared with nearby ones
c. mostly to be ellipticals since bulges formed first
d. all very obscured by the dust in their interstellar matter
e. we cannot get a good enough sense of their nature to describe them well
73. An HII region can be identified from
c. from the reddening it imposes on objects behind it
74. Molecular clouds are found mostly in the ________ of the Milky Way and other galaxies
a. bulge b. halo c. center d. globular clusters e. spiral arms
75. The biggest change in our view of our place in the Universe compared with the view 100 years ago is
a. then, we thought that the "Universe" was just the Milky Way
b. then, we believed the earth was at center of the solar system
c. then, we believed we were off at one edge of the Milky Way
e. then, we thought stars made their energy by chemical burning
76. What technical breakthough was revolutionizing astronomy 100 years ago?
b. the first mechanical calculators
c. photography began to be used in astronomy
d. accurate micrometers were introduced to measure double stars
e. radio astronomy became widely applied
77. The period-luminosity relationships for RR Lyrae and Cephid stars were easier to establish for stars in the Magellanic Clouds (nearby external galaxies) because
a. there are more of these stars in the Magellanic Clouds than in the Milky Way
b. they were easier to see in the Magellanic Clouds than in the Milky Way
c. the ones in the Magellanic Clouds are all at about the same distance
e. their proper motions are smaller, making comparisons over time with other stars more accurate
78. In the early 1900's it became possible to measure large numbers of RR Lyrae and Cepheid variables in the nearest galaxies because
a. telescopes were built larger than ever before
b. telescopes were put at high mountain sites for the first time
c. the first observatories were built in the southern hemisphere
e. the first electronic detectors were introduced
79. Galaxy collisions can
a. trigger high rates of star formation
b. perturb the planets orbiting stars in the colliding galaxies
c. drag most of the interstellar gas of the galaxies out of them
d. destroy the bulges of the galaxies
e. tear the galaxies apart so there is nothing left
80. Planetary systems form
a. within the dense disks of material surrounding very young stars
b. when young stars capture smaller bodies that foumed near them
c. in near-collisions of young stars that pull matter our of them
d. in eruptions of material from stars settling onto the main sequence
e. from convection cells in jets from young stars
81. Clumps of matter with too little mass to form stars
a. seldom collapse - they just stay part of the interstellar medium
b. usually join together to form stars
82. When clumps first collapse into young stars,
a. they cannot burn hydrogen because it has not settled into their cores yet
b. they cannot burn hydrogen until a spark ignites it
c. their activity level needs to rise before they can burn hydrogen
d. their cores must shrink and heat up to burn hydrogen
e. the hydrogen must be converted from molecular to atomis form to burn
83. An innovation that allowed Harvard College Observatory to make great advances in the early 1900s was
a. building a powerful new telescope
b. putting telescopes on high mountains where the seeing was improved
c. introducing the use of electronic detectors
d. hiring more astronomers interested in advanced theoretical calculations
84. The question of whether the spiral nebulae were galaxies like the Milky Way was settled
a. when Heber Curtis decisively defeated Harlow Shapley in this part of their debate
b. when Shapley showed how big the Milky Way is, using globular clusters
c. when Edwin Hubble used the new 100-Inch Telescope to photograph stars in nearby galaxies
d. by Herschel when he cataloged other galaxies in the process of mapping the sky
e. when Henrietta Leavitt discovered the period-luminosity relation
85. The primary way Shapley figured out where we are in the Milky Way was he
a. found the cluster of massive stars at the Galactic Center
c. counted stars in various directions to judge where the galaxy extended
d. argued that the Milky Way was similar to the spiral nebulae
86. It is important to study the center of the Milky Way because
a. it gives infrared and radio astronomers something to do
b. it helps us locate the position of the solar system within the galaxy
c. there is a unique type of star there
d. it gives a unique perspective on how a galaxy nucleus works
e. actually, there is nothing of much interest there
88. Molecular clouds are mostly composed of
89. The distance to nearby galaxies like the one in Andromeda was determined from
a. observing its main sequence stars
c. using Cepheid variables as standard candles
d. comparing its apparent size with that of the Milky Way
e. observing HII regions in it
90. The most common galaxy type found in dense galaxy clusters is
91. The order of formation of the parts of spiral galaxies is (from old to young):
a. spiral arms, disk, bulge, halo
b. disk, bulge, spiral arms, halo
c. halo, disk, bulge, spiral arms
d. halo, bulge, disk, spiral arms
e. bulge, halo, spiral arms, disk
92. If we wait a long time, the Local Group of galaxies will look
b. different because the large galaxies will have "eaten" some of the smaller ones
c. different because all the galaxies will have turned to spirals
d. like it has vanished because it will have dissipated into intergalactic space
e. full of small galaxies because collisions will break up the large ones
93. Planetary systems around other stars are
b. a topic we know very little about