200 Astronomy 2 Midterm Review Questions

1. The scientist who worked out the mathematics of the connections between electricity, magnetism, and light in the 19th century was:

 a. Albert Einstein
 b. James Clerk Maxwell
 c. Isaac Newton
 d. Wilhelm Wien
 e. Ludwig Boltzmann

2. Which of the following statements about the nucleus of a typical atom (such as the carbon in your little finger) is FALSE:

 a. the nucleus has an overall positive charge
 b. the nucleus takes up a very small amount of space compared to the entire atom
 c. the nucleus can contain both protons and neutrons
 d. the nucleus repels the electrons which move around it
 e. the nucleus contains most of the mass of the atom

3. In the 19th century, it became clear that magnetism was not a separate force, but was always produced by the action of

 a. electric charges that were in motion
 b. the gravitational pull of the Earth
 c. the strong nuclear force acting on electrons
 d. light moving through a vacuum
 e. rubbing a boy scout and a girl scout together to produce a fire

4. Which of the following statements about electromagnetic radiation is FALSE?

a. it always spreads out at the speed of light
b. it is given off by all objects that are not at a temperature of absolute zero
c. it is typically produced when charged particles oscillate
d. different waves of electromagnetic radiation differ in their wavelength or frequency
e. it consists of charged particles given off by the nuclei of atoms

5. Consider a radio wave from the transmitter of your favorite radio station, which has just reached the antenna of the radio in your room. Which of the following statements about this radio wave is CORRECT?

a. it has a frequency very close to the highest possible frequency for electromagnetic waves
b. it traveled between the transmitter and your radio's antenna at the speed of sound
c. its wavelength is much longer than the wavelength of the light you see reflected from the page of this exam
d. the wave was originally produced by electrons that were not moving (at rest) inside the transmitter
e. the reason that it could reach your radio is because all of space is filled with a medium called the aether in which electromagnetic waves can vibrate

6. Which of the following travels through space the fastest?

a. light
b. radio waves
c. infrared
d. x-rays
e. you can't fool me, all of these travel through space at the same speed

7. The fastest speed in the universe is:

a. the speed of sound
b. the speed of light
c. the speed of electron oscillations
d. the speed with which Mercury orbits the Sun
e. the speed with which weekends seem to pass

8. The light which allows you to see this very interesting exam is made up of waves. In these waves, the distance between crests is called the:

a. frequency
b. velocity
c. wavelength
d. amplitude
e. you can't fool me; in these waves, the distance between crests is zero

9. Which of the following has the longest wavelength?

a. radio
b. visible light
c. ultraviolet
d. x-rays
e. you can't fool me, all these have the same wavelength

10. Which of the following has the highest frequency?

a. visible light
b. gamma rays
c. radio waves
d. ultraviolet
e. you can't fool me, all these have the same frequency

11. A Hertz is

a. a unit of wavelength
b. a unit of frequency
c. a unit of velocity
d. a unit of loudness
e. a well-known car-rental company

12. A fashion designer decides to bring out a new line of clothing which reflects the longest wavelength of visible light. These articles of clothing will be what color to the human eye?

a. yellow-green
b. blue
c. violet
d. red
e. black

13. Which of the following statements about photons is FALSE?

a. photons always travel at the speed of light
b. photons each carry a specific amount of energy
c. a photon of light cannot pass through the atmosphere of the Earth, and thus cannot be seen at the Earth's surface
d. high energy photons have a high frequency
e. a gamma-ray photon is more energetic than a visible light photon

14. After a nice dinner around the campfire on a camping trip, you and a friend decide to get away from the fire to observe the stars. As you get farther and farther away, you see the brightness of the fire:

a. increase with distance
b. remain the same
c. decrease as the distance squared
d. change more and more in color (becoming redder)
e. this can't be answered without having more information

15. Not all wavelengths of electromagnetic radiation can penetrate the Earth's atmosphere. Of the following types of waves that come from space, which one are you likely to be able to detect most easily from our planet's surface:

a. x-rays
b. gamma rays
c. infrared waves
d. ultraviolet waves
e. radio waves of the wavelength that carry FM broadcasts

16. Most ultraviolet radiation does not penetrate to the Earth's surface. Instead it is absorbed in:

a. the ozone layer
b. the ionosphere
c. the region between the Earth and the Sun
d. stratosphere
e. tanning zone

17. Human eyes evolved to detect visible light because:

a. it is the lowest energy band of the electromagnetic spectrum and thus easiest to detect
b. it is the only kind of radiation that penetrates the Earth's atmosphere at all
c. it is the band of the spectrum which is the least Doppler shifted coming from the Sun
d. it is the band of the spectrum where the Sun puts out the most energy
e. it is the band of the spectrum where the warm Earth glows the most effectively at night

18. Which of the following statements about infrared radiation is TRUE?

a. it is the band of the electromagnetic spectrum where each wave or photon has the greatest energy
b. it was first discovered in 1800 in an experiment using sunlight and thermometers
c. unlike light, infrared can never travel as fast as the speed of light
d. while many stars give off infrared, there is nothing on Earth at the right temperature to emit it
e. it is the radiation responsible for giving sunburns (or in large doses, skin cancer)

19. Which of the following is not a type of radio wave?

a. microwaves
b. radar waves
c. the waves that carry AM or FM broadcasts
d. the sound waves coming from your transistor radio
e. the waves that carry television transmissions

20. A politician who has just said something very dumb on an AM all-talk radio station suddenly remembers the astronomy class he had in college,and starts to worry that his words are now moving outward into space at the speed of light (and will embarrass him forever). Does he have a reason to worry?

a. Yes, because all radio waves do travel at the speed of light and all of them escape from the Earth
b. No, because radio waves travel much slower than the speed of light and will take a very long time to get anywhere
c. No, because radio waves are all absorbed by the ozone layer in the Earth's atmosphere
d. No, because AM radio waves are bounced back or scattered by the ionosphere
e. Yes, because while all radio waves do not escape from the Earth, AM radio waves do

21. (In the absence of a strong magnetic field), what is the chief factor that determines what type of electromagnetic radiation objects give off:

a. their mass
b. their temperature
c. their overall motion
d. their chemical makeup
e. their size

22. The energy of random atomic and molecular motion is called

a. heat
b. the Doppler shift
c. spectroscopy
d. velocity
e. rock and roll

23. Which of the following has the greatest average energy of random atomic and molecular motion?

a. a cube of ice
b. a cube of water
c. a cube of steam
d. a cube of air (on Earth)
e. a cube of the Sun

24. An idealized object that does not reflect or scatter any radiation, but simply absorbs every bit of radiation that falls on it is called:

a. a Doppler surface
b. an electromagnetic radiator
c. a blackbody
d. a spectrum
e. a vice president

25. Two stars are giving off electromagnetic radiation. The hotter star will:

a. give off more radiation at all wavelengths
b. will have a higher average frequency of radiation
c. will radiate energy at more than one wavelength
d. will give off a continuous spectrum of waves
e. all of the above

26. An astronomer discovers a new star and wants to measure its temperature. She would do this by:

a. measuring the Doppler shift of its spectral lines
b. making a blackbody curve and finding the wavelength of the peak (maximum)
c. measuring the intensity of radio waves the star gives off
d. measuring how much light the star reflects
e. sending a graduate student with a very long (and durable) thermometer to the
star's vicinity

27. An astronomer observes two ordinary stars. The first one turns out to be twice as hot as the second. This means that the first one radiates:

a. twice as much energy as the second
b. roughly the same amount of energy as the second
c. half as much energy as the second
d. about 16 times the energy of the second
e. this problem cannot be solved with just the information we were given

29. Which of the following is NOT done best with a spectrometer?

a. measuring how bright sources of light in the universe appear
b. measuring the different colors in the spectrum
c. measuring the amount that lines are Doppler shifted
d. measuring what elements are present in a star
e. measuring what conditions are like in the cool atmosphere of a star

30. An artist who likes working with sources of light decides to make a modern sculpture out of electrified glass tubes that contain very thin(rarified) neon gas. When the sculpture is finished, and the electricity is turned on, the tubes glow with a rich red color. What we are seeing is:

a. a continuous spectrum
b. an absorption spectrum
c. an emission spectrum
d. a Doppler shift
e. all of the above

32. One of the great triumphs of spectroscopy was when astronomers identified a new element in the Sun (one that was only later found on Earth). Today, this element is called:

a. Solarium
b. Hydrogen
c. Einsteinium
d. Helium
e. Astronomium

33. If I were to scale up an atom until it were the size of a sports arena, the space filled by the positive charges inside the atom (according to the work of Ernest Rutherford early in this century) would be:

a. as big as the entire stadium (and very thinly spread out)
b. as big as the space filled by all the negative charges (that's why the atom is neutral)
c. very small (perhaps the size of a soccer ball) and in the middle
d. an extremely thin layer spread completely around the outer walls of the stadium
e. this question cannot be answered (even roughly) without knowing which kind of atom we are discussing

34. Atoms typically consist of electrons, protons, and neutrons. The most common isotope of one element, however, only has two of these three types of particles. This element is:

a. helium
b. hydrogen
c. uranium
d. carbon
e. silicon

35. Two versions of an element with different numbers of neutrons are called:

a. molecules
b. electron pairs
c. isotopes
d. ions
e. re-runs

36. As of the time our textbook went to press, 111 elements had been discovered. All of the ones over 92 have been made in physics laboratories. When element 112 is found, provided it is like the other artificially made elements, it will:

a. have only protons, no neutrons at all
b. soon be used in industry to make new kinds of plastics
c. have one of the smallest nuclei known
d. only remain stable for an extremely small fraction of a second
e. eventually be found in the Sun (with very high quality spectrometers)

37. The idea that atoms radiate energy only when their electrons move from higher to lower energy levels was first advanced by:

a. J. J. Thomson
b. Niels Bohr
c. Ernest Rutherford
d. Albert Einstein
e. Christian Doppler

38. Why do different types of atoms (elements) give off or absorb different spectral lines?

a. all elements have the same lines, but they are Doppler shifted by different amounts
b. in some elements, electrons can only move to odd numbered levels, in others only to even numbered ones
c. in heavier elements, diffraction spreads out the lines that the atom produces, making the colors different
d. because the spacing of the energy levels is different in different atoms
e. because some atoms do not have a ground state, while others have three or four

39. When an atom has lost one or more electrons, it is said to be:

a. ionized
b. excited
c. in its ground state
d. red shifted
e. over the hill

40. What happens as an electron falls from a higher level to a lower level in an atom?

a. a photon is given off
b. the color of the wave involved shifts to the red
c. a photon is absorbed
d. another electron from the lower level takes its place
e. nothing happens; electrons can only go from a lower level to a higher level

41. How do astronomers learn what elements are present in a given star?

a. look at what color light dominates its continuous spectrum
b. listen for coded signals in the radio waves it gives off in the FM band
c. look at the absorption lines in its spectrum
d. send spacecraft like Voyager to examine its make-up from close-up
e. compare visible-light photographs of the star (taken with large telescopes) to those of the Sun.

42. You are alone in a large, completely dark auditorium on Earth. What kind of telescope should I use from the other side of the auditorium to detect the electromagnetic radiation emitted by your body?

a. visible light
b. infra-red
c. ultra-violet
d. black light
e. no telescope will be effective if I am in a dark room

43. I want to examine the surface of a planet which is covered by a thick atmosphere (which includes oxygen and contains a very thick layer of water clouds that never clear). What wavelength of electromagnetic radiation would I be smartest to use:

a. visible light
b. x-rays
c. radar waves
d. ultra-violet
e. none would work

44. Planck's constant relates:

a. the energy of a wave to the number of protons in the nucleus of the atom that emitted it
b. the frequency of a wave to its energy
c. the maximum energy emitted by a blackbody to its temperature
d. the energy emitted by a star to its temperature
e. the Doppler shift of a light source to its speed

45. Which of the following consists of electro-magnetic waves with the shortest wavelength?

a. a beam of green light
b. TV transmissions bringing us Monday night football
c. the sound of the instructor's voice
d. the waves of a dental x-ray
e. the rays that tan a sunbather on the beach

46. The two regions of the electromagnetic spectrum where the Earth's atmosphere is transparent (radiation can get in) are visible light and

a. ultraviolet
b. x-rays
c. some radio waves
d. gamma-rays
e. you can't fool me, the atmosphere is transparent ONLY for visible light

47. Astronomical observatories have been available since ancient times, and many cultures set aside special sites for astronomical observations. What was missing from these observatories until about 1610 was:

a. a dark site, where lights did not get in the way
b. graduate students with the ability to climb up to higher altitudes
c. instruments for detecting radio waves
d. a way of measuring from what direction in the sky a beam of light was coming
e. telescopes

48. The most important function of an astronomical telescope is to:

a. collect as much light as possible and bring it to a focus
b. magnify (enlarge) celestial objects so we can see them clearly
c. measure the color of an object
d. bring distant objects closer by pulling on the light
e. pierce through the clouds so a cloudy night is not wasted

49. The first person (to the best of our knowledge) to turn a telescope to astronomical observations was:

a. Isaac Newton
b. Galileo Galilei
c. Adam Refractor
d. Edwin Hubble
e. Karl Jansky

50. The size of the device that gathers (collects) radiation is called a telescope's:

a. magnification
b. resolution
c. aperture
d. focal width
e. Galilean criterion

51. At the largest and most modern astronomical observatories on Earth today, which of the following regularly happens to the image formed by the telescope?

a. it is viewed by a group of graduate students who then make a sketch of it to have a permanent record
b. it is recorded on a piece of black and white film, which is then developed
c. it is reflected by a special arrangement of mirrors back into the beam and up into the sky
d. it is recorded using an electronic detector called a CCD for later analysis
e. it is recorded as a radio signal and sent by satellite to other observatories around the world

52. The earliest telescopes used by astronomers were:

a. reflectors
b. refractors
c. radio telescopes
d. about the aperture of the telescope on Mount Palomar
e. used late at night to look into the neighbors' windows

53. Your friend, a graduate student in astronomy, is giving you a special tour of the local observatory. You notice that in viewing the image from the telescope you are seeing it from underneath the primary mirror; the beam of light has come through a small hole in the main mirror to an eyepiece below. This telescope uses what focusing arrangement?

a. prime focus
b. Newtonian focus
c. Cassegrain focus
d. Galilean focus
e. out of focus

54. The largest visible-light telescopes in the world use what device to collect as much light as possible before the light is brought to a focus (to act as the light bucket)?

a. lens
b. spectroscope
c. CCD
d. mirror
e. a valley in Puerto Rico

55. Today, the largest telescope in the world that uses visible light is:

a. the Mount Palomar telescope
b. the telescope in the valley in Puerto Rico
c. the 236-inch in the Caucasus Mountains of the former Soviet Union
d. the Keck Telescope in Hawaii
e. the Hubble Space Telescope

56. Which of the following has a longer integration time (can collect light for a longer period of time) than the human eye?

a. photographic film
b. photographic plates
c. a CCD (charge coupled device)
d. all of the above
e. none of the above

57. To get away from the pressures of your astronomy class you and some friends decide to go to a football game. In the stadium, a friend gives you her binoculars to look through, and suddenly you realize that you are back to a subject covered in astronomy class. What type of telescope are you looking through when you use binoculars?

a. reflecting
b. infra-red
c. refracting
d. Newtonian
e. CCD

58. A graduate student is trying to follow the weather on Jupiter for her PhD thesis. To see individual storms in the upper atmosphere of the planet, she needs to have excellent resolution. What type of telescope would be best for her to use?

a. a refractor, with as small an aperture as possible
b. a radio telescope
c. a large reflector in an observatory located at sea level
d. a large reflector located in orbit above the Earth's atmosphere
e. you can't fool me, no telescope can show the weather on Jupiter

59. A new technique called adaptive optics allows astronomers to:

a. change the eyepieces of their telescopes much more quickly than ever before
b. compensate for changes in the Earth's atmosphere and achieve better resolution
c. increase the aperture of their telescopes by a very large factor
d. change the region of the electro-magnetic spectrum in which their telescope is able to detect radiation
e. use the observatory shop to make better eye-glasses for their graduate students

60. Why do telescopes have to have a good motorized drive system to move them quickly and smoothly?

a. because the Earth is rotating with the telescope
b. because astronomers typically have to look at many objects in the sky in a few minutes
c. because all objects in the sky vary in brightness very quickly
d. because the telescope can then be moved out from under the clouds to where it is clear
e. because shooting stars (which is what astronomers mainly follow) move so quickly across the sky during a typical night

61. When an astronomer involved in a research project says he is going to look at the observatory's plate collection, what will he be looking at?

a. a collection of souvenir plates, with painting of other observatories from around the world (astronomers collect these as a hobby)
b. a series of metal disks used for changing the aperture of reflecting telescopes
c. a series of glass plates, with light-sensitive chemicals on them, on which the appearance of the sky is recorded
d. a series of insulated plastic shields, which are used to prevent stray infrared radiation from the observatory from interfering with observations
e. what the special of the day is in the observatory cafeteria

62. Which of the following is NOT a detector of radiation from space that astronomers use or have used?

a. eyes in the head of the astronomer
b. a piece of photographic film
c. a photographic plate
d. a charge-coupled device (CCD)
e. a telescope

63. What type of telescope can be used routinely on the surface of the Earth during the DAY?

a. a visible-light telescope
b. a radio telescope
c. an x-ray telescope
d. a gamma-ray telescope
e. you can't fool me, there is no telescope that can be used during the DAY

64. You are an astronomer who wants to study a faint star in the process of being born, which gives off most of its faint radiation in the infra-red. Which of the following would NOT be a step you would want to take?

a. heat your telescope, so its delicate optics are not cold
b. try to have your telescope as high above the layers of water vapor in the Earth's atmosphere as possible
c. shield your telescope from the radiation given off by your graduate students
d. isolate your telescope in very cold surroundings
e. make sure your telescope optics are kept as free of dust as possible

65. Which of the following types of telescopes can be used ONLY above the Earth's atmosphere?

a. x-ray telescope
b. visible-light telescope
c. radio telescope
d. reflector
e. none of the above

66. To break up light into the component colors that it contains astronomers use a device called:

a. a telescope
b. a CCD
c. a spectrometer
d. Cassegrain splitter
e. interferometer array

67. The largest refracting telescope in the world, financed by a Chicago millionaire in the 1890's is at the:

a. Lick Observatory
b. Yerkes Observatory
c. Keck Observatory
d. Hale Observatory
e. Fraknoi/Morrison/Wolff Observatory

68. A very wealthy donor decides to give a large sum of money to your college or university to build the world's largest visible-light gathering telescope. From an astronomical perspective, where would be the best location to put such a telescope?

a. in a dark spot right on the campus
b. on the west coast of the U.S. very close to sea level (a location like Seattle, for example)
c. close to a large city where there are many astronomers to use it
d. on a tall, dry mountain peak
e. wherever the donor wants to put it

69. The first radio telescope was built in the 1930's by

a. Karl Jansky
b. George Ellery Hale
c. Edwin Hubble
d. a consortium of European astronomers
e. Heinrich Hertz

70. Radio telescopes of modest size can't make out as much detail (have a lower resolution) than visible light telescopes. How do astronomers overcome this limitation?

a. we have built a radio telescope in the desert that covers 1000 square miles
b. this problem can't be solved; radio telescopes will always show less detail
c. we can connect several radio telescopes some distance apart together electronically to give us the resolution of a larger telescope
d. we have launched several radio telescope satellites into orbit; each of which make out much more detail than visible light telescopes
e. the same engineers responsible for the shape of the mirror for the Hubble Space Telescope are working on this problem; stay tuned

71. In a radio telescope, the role that the mirror plays in visible-light telescopes is played by

a. a spectrometer
b. an interferometer
c. computer software
d. a special kind of lens
e. a large metal dish

72. Of the following, which has the highest resolution (ability to make out fine detail):

a. the German 100-meter radio dish
b. the 305-meter Arecibo radio dish in Puerto Rico
c. the 64-meter radio dish near Parkes, Australia
d. the Very Large Array of radio telescopes in New Mexico
e. the Very Long Baseline Array of Radio Telescopes, stretching from the Virgin Islands to Hawaii

73. Which of the following is NOT an advantage that the Hubble Space Telescope has over large telescopes on Earth?

a. the Hubble is above the Earth's atmosphere, which makes the stars twinkle and jiggle
b. the Hubble can observe at wavelengths (such as UV) which cannot be seen from the ground
c. the Hubble has a larger aperture than any visible-light telescope on Earth
d. the Hubble has a better resolution than visible-light telescopes on Earth
e. you can't fool me, all of these are advantages the Hubble has over earth-bound telescopes

74. The Kuiper Airborne Observatory was

a. a small Lear jet with an 8-inch visible-light telescope on Board used to search for lost NASA spacecraft
b. an x-ray telescope flying many kilometers up (so high that it had to be automated)
c. a balloon which was designed to fly above the ozone layer and search for ultraviolet radiation from space
d. an airplane with an infra-red telescope on board designed to fly above much of the water vapor in the Earth's atmosphere
e. an aircraft used by Hollywood movie makers when they wanted to show astronauts in free fall

75. Which of the following major telescopes is or was not located in space?

a. the Hubble Space Telescope
b. the Compton Gamma-ray Observatory
c. the International Ultraviolet Explorer
d. the Keck Telescope
e. the Roentgensatellit (ROSAT) x-ray telescope

76. What was the major problem with the Hubble Space Telescope when it was first launched into orbit?

a. its antenna wouldn't open, so the data could not be sent back to Earth
b. it was in the wrong orbit, so it dipped down into the Earth's thicker atmosphere regularly
c. its spectroscope broke during the launch
d. the mirror's shape was slightly off, so all the light did not come to a single focus
e. the mirror cover was stuck in the partly on position, making part of the mirror not usable

77. In the summer of 1996, the European Space Agency announced that it would be suspending the operations of the International Ultraviolet Explorer. Astronomers who were most unhappy about that announcement are likely to be studying what types of objects?

a. distant galaxies at the limits of the observable universe
b. cool stars just being born from cosmic raw material
c. very hot stars
d. the Moon
e. gamma-ray bursts

78. The first x-ray telescope capable of forming images of x-ray source was called:

a. Hubble
b. Einstein
c. Uhuru
d. Compton
e. Bayonne

79. When a knowledgeable amateur astronomer tells you that she has a 14-inch telescope, what does the number 14 refer to?

a. the number of times the image is magnified (how much bigger it looks)
b. the length of the main telescope tube
c. the focal length
d. the length of the eyepiece tube
e. the diameter of the primary lens or mirror

80. The most sophisticated telescope for studying cosmic gamma rays (including the mysterious gamma-ray bursts) that astronomers have today is the:

a. Keck Telescope
b. Compton Observatory
c. Hubble Space Telescope
d. the Very Large Array in New Mexico
e. Rosat

81. As astronomers learn more about the structure of the Sun, they find that it

a. has a small solid core inside
b. is made entirely of liquid and (on the outside) hot gas
c. is solid throughout, but with a large very hot atmosphere
d. is made entirely of hot gas
e. is made of billions of individual pieces of hot rock, all orbiting around each other in a whirling arrangement

82. You are out on the beach, enjoying the warm sunshine with friends. As you glance (briefly we hope) up at the Sun, the part of the Sun that you can see directly is called its:

a. corona
b. photosphere
c. chromosphere
d. core
e. heliopause

83. How do astronomers know what the outer layers of the Sun are made of?

a. we send graduate students to get samples
b. spacecraft with good shielding have approached the Sun and obtained samples
c. the surface layers of Mercury have been laid down by the Sun and are thus made of the same material as the Sun
d. the Sun's wind gives us an accurate measure of all the different elements in the Sun
e. we take an absorption line spectrum of the Sun, and the absorption lines tell us what elements are present in the outer layers

84. The most common element in the Sun is

a. helium
b. iron
c. hydrogen
d. water
e. nitrogen

85. The hotter region directly above the Sun's visible surface is called the

a. chromosphere
b. photosphere
c. corona
d. ionization region
e. convection zone

86. As you go upwards from the Sun's photosphere,

a. the temperature decreases
b. the density (number of atoms in a unit volume) decreases
c. the layers get easier to see with the unaided eye
d. the kinds of atoms present change drastically
e. only red light can emerge

87. The Sun's chromosphere and corona were discovered

a. using the first telescopes Galileo built
b. in the late 19th century through the use of a spectrograph
c. during total eclipses of the Sun
d. using spacecraft that orbited Venus, a planet with a better view of the Sun
e. by ancient shepherds, who saw reflections of the Sun in quiet pools of water

88. The Sun's chromosphere contains many jet like projections that stick up into the transition region. These spikes of gas are called:

a. coronae
b. spicules
c. plages
d. flares
e. prominences

89. Which part of the Sun's atmosphere is the hottest?

a. chromosphere
b. transition region
c. corona
d. just above the photosphere
e. you can't fool me, all these regions are at roughly the same temperature

90. Which part of the Sun's atmosphere has the lowest density (number of atoms per unit volume)?

a. corona
b. transition region
c. chromosphere
d. just above the photosphere
e. you can't fool me, all these regions are at roughly the same density

91. What mechanisms do astronomers believe is responsible for making the Sun's outer atmosphere so much hotter than its photosphere?

a. stirring by comets, meteors, and other pieces of solid material being pulled in by the Sun's strong gravity
b. light reflected back from the terrestrial planets
c. the Sun's magnetic field interacting with the charged particles that make up the atmosphere
d. the ionization of a new element called coronium
e. astronomers really don't have even a theory about what heats the Sun's outermost layers

92. Astronomers first detected the presence of a wind of particles coming from the Sun by

a. sending a spacecraft much closer to the Sun than the planet Mercury
b. by noting its effects on the atmosphere of Venus
c. by dramatic and sudden changes in the spectrum of coronium
d. using the experiments aboard Sputnik 1, the first spacecraft to go above the Earth's atmosphere
e. by noting the wind's effects on the tails of comets

93. The ten million tons of particles that escape the Sun each year in the form of the solar wind get out mainly from regions called

a. sunspots
b. spicules
c. aurorae
d. coronal holes
e. transition regions

94. Solar wind particles can be captured by the Earth's magnetosphere. When these particles spiral down along the magnetic field into the atmosphere, they are responsible for:

a. aurorae (northern and southern lights)
b. tropical storms (regions of rapidly rotating air)
c. the greenhouse effect
d. the reddish color we see during sunsets
e. the poor quality of television programming in the world's northern hemisphere

95. The granulation pattern that astronomers have observed on the surface of the Sun tells us that:

a. the Sun is a lot cooler on the inside than on the outside
b. the Sun's surface is made of a thin solid that cracks easily
c. hot material must be rising from the Sun's hotter interior
d. the solar wind must consist of very small (low-mass) particles
e. the Sun accumulates a lot of dirt and dust because of its large gravity

96. Sunspots are darker than the regions of the Sun around them because

a. they consist of different elements than the rest of the Sun
b. they are located in the corona and not on the photosphere
c. they move much faster around the Sun than other material and thus heat up
d. they are the shadows of the planets and asteroids seen on the bright surface of the Sun
e. they are cooler than the material around them (although still very hot compared to Earth temperatures)

97. Astronomers have concluded that the Sun's activity varies in an 11-year cycle. Which of the following statements about this cycle is TRUE:

a. Every 11 years sunspots completely cover the Sun, making its surface much darker
b. The number of sunspots gets larger and smaller over the course of 11 years
c. When sunspots are at a minimum, we get the largest number of flares and prominences
d. The Sun's activity cycle shows absolutely no connection to its magnetic field
e. The Sun's activity cycle is directly connected to the number of earthquakes at the continental plate boundaries on Earth

98. How do astronomers know how strong the magnetic field of the Sun is?

a. they measure the magnetic field of the Earth, which is a direct result of the magnetic field of the Sun
b. they measure the Sun's rotation using the Doppler effect
c. they count the number of days in the year that we get an aurora in the upper atmosphere
d. the measure the Zeeman effect (the splitting of spectral lines)
e. the diameter of a star is directly related to the size of its magnetic field

99. A Canadian college student who has taken an astronomy class goes home for the holidays and persuades his parents to let him borrow the family car. When he returns, he finds that his parents are very angry with him, claiming he left the garage door open. Yet he remembers that he carefully closed the garage door. After consulting with his astronomy instructor, he comes up with an alternative explanation for why the garage door is open. Which of the following is PART of that explanation?

a. The Sun was so bright and high in the sky in December in Canada that it got into his parents' eyes
b. There was an eclipse of the Sun
c. It was a time of solar maximum, and there had been a flare on the Sun
d. No aurorae had been seen in the sky for many months
e. The number of sunspots had reached an all-time minimum

100. Which of the following is not part of some active regions on the Sun?

a. sunspots
b. flares
c. plages
d. prominences
e. granulation

101. Astronomers now realize that active regions on the Sun are connected with

a. the dark regions between the bright granulation cells on the photosphere
b. loops of magnetic field emerging from the surface of the Sun
c. the absence of sunspots during a solar minimum
d. great tropical storm systems in the Earth's atmosphere
e. changes in the gravitational pull of the Sun over different parts of its photosphere

102. Astronomers have found that the level of the Sun's activity varies over the centuries. How did they come to realize that this is so:

a. historical records of the number of sunspots seen on the Sun
b. measuring the amount of radioactive carbon in tree rings
c. historical records of auroral activity
d. all of the above
e. none of the above

103. On Earth, a period of low solar activity, such as the Maunder Minimum, means:

a. less volcanic activity
b. a climate with cooler temperatures
c. a significant increase in the number of aurorae seen
d. a much larger number of cloudy days
e. very little; there is no connection between the Sun's activity and what happens on Earth

104. Recently, some engineers and scientists have proposed building spaceships with enormous "sails" that catch the solar wind and use it to move the ship. What kinds of particles would be hitting this sail (i.e. what is the solar wind mostly made of):

a. nuclei of heavier atoms such as iron and nickel
b. calcium atoms
c. electrons and protons
d. gamma-rays
e. scientists do not have any idea of the composition of the solar wind; it is very mysterious

105. When we use the light of atoms such as hydrogen and calcium to examine the Sun's outer layers, we can see bright "clouds" in the chromosphere
right around the location of sunspots. These bright clouds are given the name:

a. granules
b. spot umbras
c. active regions
d. Zeeman rings
e. plages

106. A friend (who does not have the vast new awareness which you have gained from this course) suggests that the mechanism that keeps the Sun shining as brightly as it does is the burning of coal. You brilliantly challenge his theory! Your challenge comes in several steps; which of the following is one of those steps?

a. we have found many more neutrinos than we expected in our underground experiments
b. new protostars shine by gravitational collapse (the heat of clumping)
c. the dating of radioactive rocks show that the Earth and the Sun are billions of years old
d. most of the Sun is made of antimatter (which explodes when it touches matter)
e. the C-N-O cycle can also produce helium

107. When did scientists begin to understand how the Sun produces all the energy that it does?

a. Most of the process was already understood by the ancient Greeks
b. Most of the process was understood by the end of the 18th century (the year 1800)
c. Most of the process was understood by the end of the 19th century (the year 1900)
d. The process was not well understood until the 1930's
e. You can't fool me; astronomers still don't have a clue about how the Sun produces energy

109. Physicists Kelvin and Helmholtz in the last century proposed that the source of the Sun's energy could be:

a. radioactive rocks
b. a slow contraction
c. meteorites falling in
d. the annihilation of antimatter
e. nuclear fusion

110. Today we realize that the source of energy for the Sun is a process called

a. nuclear fusion
b. Kelvin-Helmholtz contraction
c. mechanical to thermal energy conversion
d. radioactivity
e. dilithium crystal moderation

111. According to the formula E=mc2

a. mass has to travel at the speed of light before it can produce any energy
b. energy can travel much faster than light (in fact its speed can be the speed of light squared)
c. a little bit of mass can be converted into a substantial amount of energy
d. when two masses collide, we always get a lot of light
e. Einstein was a male chauvinist twice over

112. In the formula E=mc2 the letter c stands for

a. the speed of sound
b. the speed of an electron around the nucleus
c. the amount of energy contained in one hydrogen nucleus
d. the energy of a neutrino emerging from the Sun
e. the speed of light

113. The antimatter version of an electron is called a

a. proton
b. neutrino
c. antitron
d. positron
e. gammatron

114. In the Sun, when a positron and an electron collide, they will produce:

a. a deuteron
b. a neutron
c. hydrogen
d. a neutron
e. energy in the form of a gamma ray

115. Which of the following statements about antimatter is true?

a. antimatter is only a theory, we have no evidence that it exists
b. antimatter only exists in Earth laboratories; it cannot be made in stars
c. antimatter cannot be made in laboratories; we have tried but it just can't be done
d. when equal amounts of matter and antimatter meet, they become pure energy
e. our telescopes clearly see many antimatter stars in the Milky Way galaxy

116. As originally suggested by Wolfgang Pauli, neutrinos have the following property:

a. they travel at the speed of light
b. they have no mass
c. they interact very weakly with ordinary matter
d. they can be considered little packets of energy
e. all of the above

117. A college friend of yours who has been postponing taking any science courses hears you talking about the generation of nuclear energy in the Sun and makes the following observation: "The whole idea of the atomic nucleus is pretty ridiculous. If an oxygen nucleus consists of eight protons and eight neutrons, the charge on the nucleus is positive. Since even I learned in high school that like charges repel, such a nucleus would find itself repulsive and quickly fall apart." How would you answer his argument.

a. gravity is much stronger than electric repulsion and holds every nucleus together
b. the neutrons in the nucleus are negative, so they cancel the positive charge on the protons
c. the nuclear force, which is attractive and stronger than electricity, holds the nucleus together
d. the electrons outside the nucleus repel the protons and keep them inside the nucleus
e. there is no answer; scientists do not have a clue about how the nucleus manages to keep itself together

118. Which of the following particles has the lowest mass?

a. a neutrino
b. a proton
c. a neutron
d. an electron
e. the nucleus of a hydrogen atom

119. The strongest force we know is

a. gravity, which holds the Earth and the Sun together
b. electricity, which pulls unlike charges together
c. the nuclear force which holds nuclei together
d. the attraction of Bayonne, New Jersey, for tourists
e. none of the above

120. When two light elements undergo nuclear fusion,

a. the total mass involved increases
b. the like charges in the nuclei attract, pulling the nuclei together faster and faster
c. some of the energy in their mass is released
d. only one survives; the other turns into a release of pure energy
e. the result is always to make nuclei of iron

121. When a large nucleus breaks apart (or is broken apart) into two smaller pieces, this is called

a. nuclear fusion
b. nuclear binding
c. the p-p chain
d. equilibrium breaking
e. nuclear fission

122. If the "fuel" for nuclear fusion is nuclei of hydrogen, and the Earth's oceans are filled with hydrogen atoms all being jostled together, why isn't there a lot of fusion happening in our oceans?

a. the hydrogen in our oceans is the wrong type of hydrogen for fusion
b. for hydrogen nuclei to fuse, they must get very close to each other, which the nuclei in the oceans cannot do
c. for hydrogen to fuse, the nuclei must first join together in long p-p chains of atoms
d. on Earth, only hydrogen that is in deep mines under the Earth is far enough underground for fusion
e. you can't fool me, hydrogen in the Earth's oceans does undergo fusion; that's what keeps our oceans warm

123. Where in the Sun does fusion of hydrogen occur?

a. only in the core
b. only near the photosphere (its visible surface layer)
c. pretty much throughout the Sun
d. only in the layer where there is a lot of convection going on
e. nowhere

124. If it takes an average of 14 billion years before any proton inside the Sun will undergo fusion, and the Sun is only about 5 billion years old, why do astronomers believe that fusion is going on there now?

a. fusion begins with particles even lighter than protons, which fuse more easily
b. there are an enormous number of protons inside the Sun, so some will fuse much sooner than the average
c. fusion takes place in the hot atmosphere of the Sun (where it can happen faster), not inside (where it is slow)
d. fusion inside the Sun involves carbon, not protons; carbon fuses much more quickly
e. there is no fusion going on inside the Sun, and the fact cited in the question is one of the reasons why

125. The process of fusion that keeps our Sun shining begins with which building blocks?

a. two electrons
b. two deuterons
c. two protons
d. two Einsteinium nuclei
e. two neutrinos

126. Which of the following is NOT a product of the first step in the p-p chain of nuclear fusion?

a. a form of hydrogen
b. a positron
c. a neutrino
d. a deuteron
e. a form of helium

127. At the end of the p-p chain of nuclear fusion in the Sun, hydrogen nuclei have been converted into:

a. carbon nuclei
b. heavy hydrogen nuclei
c. antimatter and nothing else
d. a helium nucleus
e. a lithium nucleus

128. Who pays the bill for the energy generated by nuclear fusion in the Sun? In other words, where does the energy pouring out of the Sun come from ultimately?

a. the Sun is spinning more slowly as time goes on; rotation energy is lost
b. heavy nuclei are breaking apart into lighter nuclei
c. a little bit of mass is lost in each reaction and is turned into energy (the Sun is losing mass)
d. material is falling into the Sun and being vaporized to produce energy
e. American taxpayers pay this bill, as they do so many others!

129. What happens to the positron created during the p-p chain of nuclear reactions inside the Sun?

a. it merges with a proton to become a deuterium (heavy hydrogen) nucleus
b. it quickly collides with an electron and turns into gamma-ray energy
c. it ultimately forms an anti-helium nucleus
d. it turns quickly into a neutrino, which can escape from the Sun
e. it just sits there at the core of the Sun for billions of years, unable to interact

130. The Sun is an enormous ball of gas. Left to itself, a ball of so many atoms should collapse under its own tremendous gravity. Why is our Sun not collapsing?

a. the gravity of the planets around the Sun pulls its material outward, preventing collapse
b. the pressure of the corona keeps the Sun's main body of gases confined to a small volume
c. nuclear fusion in the core keeps the temperature and the pressure inside the Sun at a high enough level so that gravity is balanced
d. neutrinos from the core exert an enormous pressure on the layers of the Sun as they travel outward, and keep our star from collapsing
e. you can't fool me, the Sun is shrinking all the time, it just happens very slowly

131. When great currents of hot material rise inside the Sun (and cooler material sinks downward), energy is being transferred by a process known as:

a. convection
b. radiation
c. conduction
d. equilibrium
e. politics

132. Which of the following, produced at the core of the Sun, will take the shortest time to emerge from the Sun's photosphere (surface)?

a. a photon (wave) of gamma-rays
b. a positron
c. a neutrino
d. a deuteron
e. an x-ray produced after radiation has interacted with matter in the core

133. Which part of the Sun has the greatest density?

a. the photosphere
b. the core
c. the convection region
d. the corona
e. you can't fool me; since the Sun is made of gas, all its parts have the same density

134. Which of the following is a way for astronomers to learn more about the interior of the Sun?

a. study the corona during eclipses of the Sun
b. study the oscillations (pulsations) of the Sun's surface
c. follow the orbit of Mercury, the closest planet to the Sun
d. take photographs of the Sun in the light absorbed by hydrogen atoms
e. study the accounts in ancient legends of the realm where the devil is supposed to live

135. The Global Oscillations Network Group (GONG) Project is now engaged in:

a. measuring where earthquakes happen around the Earth by the waves they generate
b. measuring the number of sunspots on the surface of the Sun at any given hour
c. measuring the quality of the "seeing" (the jiggling of the Earth's atmosphere) at all the major observatories around the world
d. measuring the pulsations of the Sun from stations around the world
e. measuring how problems on the World Wide Web are affecting the communication among astronomers

136. Which of the following is the best statement concerning the experiments that have been searching for neutrinos from the Sun?

a. So far, all the experiments have had technical problems detecting neutrinos, which are very "antisocial" and thus very hard to catch
b. The experiments work OK, but they have so far found no neutrinos at all; not a single one
c. All the neutrinos found in the experiments have been one of the other two types of neutrinos, not the electron neutrino that we expect coming from nuclear fusion in the Sun
d. Now that they are working right, the experiments have found almost exactly the number of neutrinos that our models of the Sun have predicted should be coming
e. The experiments have found only between 1/3 and 2/3 the number of neutrinos arriving from the Sun that our models predicted should be coming

137. Which of the following is NOT an experiment that is searching for neutrinos coming from the Sun?

a. looking for radioactive argon atoms in a tank of cleaning fluid deep in an underground mine
b. looking for changes in the Doppler shift of lines in the atmosphere of the Sun
c. looking for radioactive gallium in a vast quantity of ordinary gallium
d. looking with sensitive light meters in a giant vat of pure water deep underground in Japan
e. all of the above are ways to search for neutrinos

138. When an astronomer rambles on and on about the luminosity of a star she is studying, she is talking about:

a. what color the star is
b. the total amount of mass in the star
c. the star's apparent size (the size seen from Earth)
d. how much energy the star gives off each second
e. the elements she can see in the star's spectrum

139. Two stars have the same luminosity, but star B is three times farther away from us than star A. Compared to star A, star B will look

a. three times brighter
b. nine times brighter
c. nine times fainter
d. three times fainter
e. just as bright as A

141. An exhausted-looking astronomer comes off the mountain where his observatory is located and tells you he has been doing photometry. What has he been up to?

a. taking photos through bedroom windows in the valley below
b. measuring the positions of stars on photographic plates taken over many years
c. putting the light of stars through a spectrograph to measure what elements are present
d. measuring the brightness of different stars
e. counting the number of stars in different star clusters (groups)

142. The first astronomer who did photometry in a systematic way (even though he did not have a telescope) was

a. Hipparchus
b. Ptolemy
c. Kepler
d. Galileo
e. Hubble

144. Why are astronomers much more interested in the luminosity of a star than its apparent brightness?

a. because luminosity can be measured exactly, but apparent brightness can only be roughly estimated
b. because the luminosity tells us how bright a star really is, while apparent brightness only tells us how bright it happens to look from Earth
c. because the luminosity also tells us what elements the star is made of, while apparent brightness cannot tell us a star's chemical make-up
d. because luminosity can tell us how bright it is inside the star, while apparent brightness only tells us about its outside layers
e. you can't fool me, there is no difference between luminosity and apparent brightness; they are merely different terms for the same property of a star

145. Which color star is likely to be the hottest?

a. red
b. green
c. blue-violet
d. yellow
e. orange

146. Which type of star is the coolest (has the lowest surface temperature)?

a. O
b. A
c. M
d. F
e. G

147. A team of astronomers takes spectra of thousands of different stars. The spectra show significant differences. The main reason the spectra of stars do not all look alike is that stars

a. are located in many different regions of the Milky Way
b. have different temperatures
c. are made of significantly different elements
d. sometimes have atmospheres and sometimes do not
e. change their spectra as they evolve, and so young stars have very different spectra from older ones

148. If hydrogen is the most common element in the universe, why do we not see the lines of hydrogen in the spectra of the hottest stars?

a. in the hottest stars, hydrogen nuclei are forced to break apart into smaller nuclei
b. in the hottest stars, all hydrogen in the star has quickly fused into helium
c. in the hottest stars, hydrogen can quickly combine with oxygen to make H2O, whose spectrum consists of completely different lines
d. in the hottest stars, the hydrogen atoms experience a huge Doppler shift, which moves the lines in the spectrum to a completely unrecognizable place
e. in the hottest stars, hydrogen atoms are ionized, and so there are no electrons to produce lines in the spectrum

149. Astronomers arrange the stars into groups called spectral classes (or types) according to the kinds of lines they find in their spectra. These spectral classes are arranged in order of decreasing:

a. decreasing surface temperature
b. increasing mass
c. increasing amount of hydrogen
d. decreasing distance from us
e. you can't fool me, there is no order to the spectral types (that's why the letters are not in alphabetical order)

150. After days and days of work, a group of graduate students has finally measured the wavelengths of hundreds of lines in the spectrum of a distant star. If a number of the lines come from molecules such as titanium oxide, the star is likely to be which spectral type:

a. O
b. B
c. A
d. M
e. we need more information; lines from molecules can be found in stars of every spectral type

151. The astronomer who, at the turn of the century, measured the spectra of hundreds of thousands of stars, leaving a catalog that astronomers used for the rest of the century, was:

a. Edwin Hubble
b. Annie Cannon
c. Cecilia Payne
d. Joseph Fraunhofer
e. James Lick

152. A graduate student has spent a whole year doing a careful analysis of the spectrum of a star. While she has found lines from many elements, there was not a trace of the element helium in the spectra she has been analyzing. From this she can now conclude:

a. there is most likely no helium anywhere in the star
b. all the helium must be in the core of the star; there is none of it in the outer regions
c. since helium shows lines only in hot stars, this star must be relatively cool
d. since helium is the kind of element that quickly bonds with others, all the helium in this star must be in the form of molecules
e. the student was not surprised, because NO star ever shows any lines of helium

153. At an astronomical conference, an astronomer gives a report on a star which has recently begun to interest astronomers because of hints that it may have a planet around it. In his report, the astronomer gives the speed with which this star is moving away from the Sun. How did the astronomer measure this speed?

a. by seeing how the luminosity of the star has been decreasing as it moves farther and farther away
b. by seeing the star become much redder than it used to be
c. by measuring the diameter of the star (which is easy to do) and noticing that it is getting smaller and smaller
d. by looking at the Doppler shift in the lines of the star's spectrum
e. the astronomer must be making up stories to impress his colleagues; there is no way to measure the speed with which stars move away or toward us.

154. A star moving toward the Sun will show:

a. a shift in the spectral lines toward the blue end (as compared to the laboratory positions of these lines)
b. a significant increase in its apparent brightness (magnitude)
c. more and more helium lines as it approaches us
d. a shift in the spectral lines toward the red end (as compared to the laboratory positions of these lines)
e. no change that can be measured with our present-day instruments

155. The motion of a star across the sky (perpendicular to our line of sight) is called its

a. radial velocity
b. Doppler shift
c. light travel time
d. proper motion
e. spectral type

156. Imagine that a brilliant but quirky scientist in the biology department manages to put you in a deep freeze and you wake up in a million years. Which of the following statements about the sky you would see in that future time is correct?

a. all the stars and constellations would look exactly the same as they do now
b. all the stars we can see in the sky today will have died in a million years
c. if you could see them up close, almost all the stars in the sky today will have changed their color significantly in a million years
d. because of proper motion, a number of the familiar constellations will look somewhat different in a million years
e. at the present time, astronomers do not know enough about the universe to say what the sky might be like in a million years

157. An astronomer whose secret hobby is riding merry-go-rounds has dedicated his career to finding the stars that rotate the most rapidly. But the stars are all very far away, so none of them can be seen to spin even when he looks through the largest telescopes. How then can he identify the stars that rotate rapidly?

a. all stars that rotate show a huge Doppler shift toward the blue end of the spectrum
b. stars that rotate have a significantly lower luminosity than stars that do not rotate
c. stars that rotate have much wider lines in their spectra than stars that do not
d. stars that rotate bring the light atoms (like hydrogen) spinning up to their surfaces; so they can be identified by the elements they contain
e. this astronomer better spend some more time enjoying his hobby, because he is not doing well at his job; there is no way we know about today to identify stars that rotate

158. Most of the stars we can see with the unaided eye from Earth are

a. intrinsically fainter than the Sun
b. very close to us (among the closest stars)
c. more luminous (intrinsically brighter) than the Sun
d. only visible to our eyes because they actually consist of three or more stars blending their light together
e. undergoing some sort of explosion which makes their outer layers unusually bright

159. Most of the really bright stars in our sky are NOT among the stars that are very close to us. Why then do they look so bright to us?

a. we see them in crowded regions of stars, which give us the impression that the stars there are brighter than they really are
b. all the brightest stars are red, and red color is much easier to see against the black night sky
c. these stars vary in brightness (flashing brighter and dimmer) and are thus easier to notice
d. these stars are intrinsically so luminous, that they can easily be seen even across great distances
e. actually, this is just an optical illusion; all stars are really the same brightness

160. Some "superstars" give off more than 50,000 times the energy of the Sun. Why are there no such stars among the stars that are close to the Sun?

a. because conditions in the "neighborhood" of the Sun only permit low-mass (low luminosity) stars to form
b. because such very luminous stars are extremely rare, and thus any small neighborhood in the Galaxy is unlikely to contain one of them
c. because all stars in the vicinity of the Sun have planets, and planets rob a star of its brightness
d. because such superstars only give off a lot of energy for a year or so, before they die
e. because such superstars are really several hundred stars blending their light together (but so far away we can't distinguish individual stars); nearby stars are easy to separate

161. The most common kinds of stars in the Galaxy have

a. low luminosity compared to the Sun
b. spectra that show they contain mostly carbon
c. enormous masses compared to the Sun
d. diameters thousands of times greater than the Sun's
e. a dozen or more stars in close orbit around them

162. Which of the following characteristics of a single star (one that moves through space alone) is it difficult to measure directly?

a. its apparent brightness
b. its temperature
c. its chemical composition
d. its mass
e. you can't fool me, all of these are quite easy to measure directly

163. Two stars that are physically associated (move together through space) are called

a. double stars
b. main sequence stars
c. brown dwarf pairs
d. first contact stars
e. binary stars

164. Which of the following statements about spectroscopic binary stars is FALSE?

a. visually we can only see one star
b. some of the lines in the spectrum are double, with the spacing changing over time
c. an analysis of the ways the lines in the spectrum change allows us to calculate the star's distance directly
d. we can use the spectrum to determine the sum of the masses of the two stars
e. we can often use the changes in the positions of the spectral lines to measure the radial velocity of the stars in the system

165. I am measuring the spectrum of the stars in a spectroscopic binary system. When one of the stars is moving toward the Earth in its orbit, we observe

a. that the lines in its spectrum get brighter
b. that the lines in its spectrum merge with the lines of the other star
c. that it is no longer possible to learn what elements are in the star
d. that the lines in its spectrum show a blue-shift
e. none of the above

166. Which law do astronomers use to determine the masses of the stars in a spectroscopic binary system?

a. Wien's Law
b. Kepler's Third Law
c. Stefan-Boltzmann Law
d. Hubble's Law
e. Jenny Craig's Law

167. Stars that do not have what it takes to succeed as a star (i.e. do not have enough mass to fuse hydrogen into helium at their centers) are called:

a. extras
b. red giants
c. spectroscopic stars
d. brown dwarfs
e. main sequence stars

169. In 1995, astronomers identified a dim object called Gliese 229b, which appears to be a brown dwarf. Which of the following observations helped convince astronomers that they had indeed found an (elusive) brown dwarf?

a. its spectrum showed the molecule methane in the object's atmosphere
b. its spectrum showed ionized helium (which can only exist at very cool temperatures)
c. the star to which this object was a companion was also extremely dim
d. it had an enormous radial velocity
e. radio-telescope observations caught hints of the song "Hi-ho, hi-ho, it's off to work we go..."

170. Why can astronomers not measure the diameters of stars directly?

a. stars are so bright, their light burns out all the delicate instruments we would use to measure their diameters
b. stars change their diameters regularly, growing alternately larger and smaller
c. stars are so far away, we cannot resolve (distinguish) their diameters
d. stars are all in binary systems, and we can only see the combined diameter of both stars
e. you can't fool me; measuring the diameter of any star is a relatively easy process

171. For what type of star can astronomers measure the diameter with relative ease?

a. visual double stars
b. white dwarf stars
c. main sequence stars
d. eclipsing binary stars
e. any star that is not a brown dwarf

172. An H-R Diagram plots the luminosity of stars against their:

a. mass
b. diameter
c. surface temperature
d. age
e. location in the sky

173. In an H-R diagram, where can you check the spectral type of a star (whether it is an O type star or a G type star, for example)?

a. along the right (vertical axis)
b. along the bottom (the horizontal axis)
c. only in the red giant region
d. only on the main sequence
e. H-R diagrams have nothing to say about spectral types

174. Who was the astronomer who is the "H" in H-R diagram?

a. Hubble
b. Humason
c. Hertzsprung
d. Huggins
e. Hoyle

175. Ninety percent of all stars (if plotted on an H-R diagram) would fall into a region astronomers call:

a. the supergiant region
b. the main sequence
c. the white dwarf region
d. the visual region
e. the twilight zone

176. Measurements show a certain star has a very high luminosity (100,000 x the Sun's) while its temperature is quite cool (3500ø K). How can this be?

a. it must be a main sequence star
b. it must be quite small in size
c. it must be quite large in size
d. it must be brown dwarf and not a regular star
e. this must be an error in observations; no such star can exist

177. A white dwarf, compared to a main sequence star with the same mass, would always be:

a. larger in diameter
b. smaller in diameter
c. the same size in diameter
d. younger in age
e. less massive

178. Imagine that powerful telescopes in the future give us a truly representative sampling of all the stars in the Sun's cosmic neighborhood. Where on the H-R diagram would most of the stars in our immediate vicinity lie?

a. in the upper right, among the supergiants
b. in the upper left, among the bright main sequence stars
c. in the middle of the main sequence, roughly where the Sun is
d. in the lower left, among the white dwarfs
e. in the lower right, among the least luminous main sequence stars

179. A team of astronomers discovers one of the most massive stars ever found. If this star is just settling down in that stage of its life where it will be peacefully converting hydrogen to helium in its core, where will we find it on the H-R diagram?

a. among the supergiants, in the upper right
b. a little bit below the Sun on the main sequence
c. among the most brilliant of the white dwarfs, in the lower left
d. near the very top of the main sequence, in the upper left
e. it could be anywhere on the diagram; we would need more information to
determine its place

180. Astronomers identify the main sequence on the H-R diagram with what activity in the course of a star's life?

a. forming from a reservoir of cosmic material
b. fusing hydrogen into helium in their cores
c. letting go of a huge outer layer
d. dying
e. you can't fool me; so many stars are on the main sequence that there is no special stage in a star's life that can be identified with it

181. Stars that lie in different places on the main sequence of the H-R diagram differ from each other mainly by having different:

a. compositions
b. internal structure
c. masses
d. radial velocities
e. ways that they formed

182. One of your good friends who is on a diet asks you to point out the stars with the smallest mass on an H-R diagram that you are studying. Where are you sure to find the stars with the lowest mass on any H-R diagram?

a. among the white dwarfs
b. among the stars at the top left of the main sequence
c. among the stars at the bottom right of the main sequence
d. among the supergiants
e. stars with low mass can be located anywhere at all in the H-R diagram

183. The apparent brightness of stars in general tells us nothing about their distances (i.e. we cannot assume that the dimmer stars are farther away.) In order for the apparent brightness of a star to be a good indicator of its distance, all the stars would have to be:

a. at the same distance
b. the same composition
c. the same luminosity
d. by themselves instead of in binary or double-star systems
e. a lot farther away than they presently are

184. The original definition of a meter was

a. the distance from the extended index finger of the Emperor Napoleon to his nose
b. one thousandth of the distance from Paris to London
c. one billionth the distance from the Earth to the Sun
d. one ten-millionth of the distance from the Earth's equator to its pole
e. one thousandth the diameter of the town of Bayonne, New Jersey

185. Kepler's Laws can give us the relative distance of objects in the solar system. To convert these relative distances into actual distances, we need to:

a. measure the mass of the Sun
b. measure the size of the Earth
c. measure the distance directly to any object orbiting the Sun
d. measure the length of the year exactly
e. measure the time it takes for the Earth to spin once on its axis

186. An astronomical unit is:

a. the distance to the nearest star
b. the distance covered by light in one year
c. the distance covered by light in one month
d. the time it takes for the solar system to turn once on its axis
e. the average distance between the Earth and the Sun

187. Today, astronomers can measure distances directly to worlds like Venus, Mars, the Moon, or the satellites of Jupiter by

a. bouncing radar beams off them
b. using x-ray telescopes
c. using the Hubble Space Telescope to triangulate with
d. using Cepheid variable stars that lie behind the planets
e. sending graduate students out with very long tape measures

188. Why did it take astronomers until 1838 to measure the parallax of the stars?

a. because most stars are too faint to see without a good telescope
b. because the stars are so far away that their annual shift of position in the sky is too small to see without a telescope
c. because detecting parallax requires measuring a spectrum, which only became possible in the 1830's
d. because cepheid variable stars had not been discovered earlier
e. because no one before then could conceive of the Earth moving around the Sun

189. As astronomers use the term, the parallax of a star is

a. one half of the Doppler shift due to its radial velocity
b. always equal to 1 AU
c. one half the angle that a star shifts when seen from opposite sides of the Earth's orbit
d. the time it takes a Cepheid variable star to go through one cycle of its brightness changes
e. the time it takes for a star to move one second of arc of proper motion

190. How far away would a star with a parallax of 0.2 arcsec be from us?

a. 2 parsecs
b. 5 parsecs
c. 0.2 parsecs
d. 0.5 parsecs
e. we need more information to answer this question

191. If a star is 10 parsecs away, how long ago did the light we see from it tonight begins its journey toward us?

a. 10 years
b. 0.1 years
c. 10,000 years
d. 32.6 years
e. 6100 years

192. The instrument astronomers have been using to make the most precise measurements of stellar parallax we have ever had is

a. the Keck telescope in Hawaii
b. the Very Large Array of radio telescopes
c. the Compton Gamma Ray Observatory
d. the Hipparcos satellite
e. a swimming-pool sized vat of cleaning fluid deep in the shaft of a gold mine

193. An astronomer is observing a single star (and one which does not vary) which she knows is located about 40 LY away. What is the most likely method she or her colleagues used to obtain that distance?

a. bouncing radar beams off the star
b. measuring the star's parallax
c. the period-luminosity relationship
d. Kepler's laws
e. Hubble's law

194. A type of star that has turned out to be extremely useful for measuring distances is

a. the eclipsing binaries
b. the Cepheid variables
c. the main sequence stars
d. the white dwarf stars
e. the stars that lie in the constellation of Orion

195. A light curve for a star measures how its brightness changes with

a. time
b. distance
c. mass
d. radial velocity
e. age

196. How do astronomers know that pulsating variable stars are actually expanding and contracting in diameter?

a. it is clear just by looking at the light curve
b. they discover this by looking at an H-R diagram
c. they can measure a regularly varying Doppler shift in the spectral lines
d. they can measure the star's changing pull on a companion star around it
e. astronomers are just guessing; at the distances of the stars, there is no way to show that stars are expanding and contracting

197. Why do Cepheid variables have that strange name?

a. they were discovered by an astronomer named George Cepheid
b. the first star discovered to be this kind of variable had the Latin name Cepheidus
c. the word Cepheid means changing in brightness in ancient Greek
d. the first such variable was discovered in a constellation called Cepheus
e. the astronomer who discovered them had a dog named Ceffie

198. The period-luminosity relationship for Cepheid variables was discovered by

a. John Goodricke
b. Henrietta Leavitt
c. Edward Pickering
d. Henry Norris Russell
e. Edwin Hubble

199. The measurement of cosmic distances was helped tremendously by the discovery, in the early part of the 20th century, that in Cepheid variable stars, the average luminosity was related to:

a. their radial velocity
b. the abundance of hydrogen in their atmospheres
c. their distance from the Sun
d. the length of time they took to vary
e. their parallax

200. Which of the following stars is a Cepheid variable?

a. Sirius
b. Betelgeuse
c. Rigel
d. Mizar
e. Polaris