SAMPLE TEST: Stars and Galaxies
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____1.Stars of which color have the highest surface temperature?
a. / red / c. / yellowb. / orange / d. / blue
____2.A star with a surface temperature between 5000 K and 6000 K appears ____.
a. / blue / c. / yellowb. / red / d. / white
____3.The mass of a star can be determined by studying ____.
a. / the wavelength of light emitted by the starb. / the color of the star
c. / the distance between the star and Earth
d. / binary star systems
____4.Stars of which color have the coolest surface temperature?
a. / red / c. / yellowb. / orange / d. / blue
____5.A light-year is approximately ____.
a. / 9.5 trillion kilometers / c. / 150 million kilometersb. / 95 trillion kilometers / d. / 150 billion kilometers
____6.Stellar distances are usually expressed in what units?
a. / miles / c. / light-yearsb. / kilometers / d. / none of the above
____7.Which of the following is true about parallax?
a. / It is used to measure distances to stars.b. / The parallax angles of distant stars are too small to measure.
c. / The nearest stars have the smallest parallax angles.
d. / both a and b
____8.The measure of a star’s brightness is called its ____.
a. / magnitude / c. / intensityb. / parallax / d. / color index
____9.Which of the following does NOT affect the apparent brightness of a star?
a. / how old the star is / c. / how hot the star isb. / how big the star is / d. / how far away the star is
____10.If star A is farther from Earth than star B, but both stars have the same absolute magnitude, what is true about their apparent magnitude?
a. / Both stars have the same apparent magnitude.b. / Star A has the greater apparent magnitude.
c. / Star B has the greater apparent magnitude.
d. / Apparent magnitude is not related to distance.
____11.Which magnitude would be associated with the brightest star?
a. / 15 / c. / 5b. / 10 / d. / –5
____12.The difference in the brightness of two stars with the same surface temperature is attributable to their____.
a. / densities / c. / agesb. / colors / d. / sizes
____13.Which of the following is NOT a type of nebula?
a. / reflection / c. / spiralb. / emission / d. / dark
____14.A Hertzsprung-Russell (H-R) diagram shows the relationship between ____.
a. / absolute magnitude and apparent magnitudeb. / temperature and absolute magnitude
c. / parallax and temperature
d. / apparent magnitude and parallax
____15.About 90 percent of stars on the H-R diagram are ____.
a. / supergiants / c. / white dwarfsb. / main-sequence stars / d. / black holes
____16.Which main-sequence stars are the most massive?
a. / red / c. / yellowb. / orange / d. / blue
____17.Which main-sequence stars are the least massive?
a. / red / c. / yellowb. / orange / d. / blue
____18.According to Figure 25-1, which main-sequence stars are brightest?
a. / the smallest / c. / the hottestb. / the coolest / d. / none of the above
____19.According to Figure 25-1, the sun has an absolute magnitude of ____.
a. / –5 / c. / 5b. / 0 / d. / 5000
____20.Another name for the interstellar matter that will eventually form a star is ____.
a. / supernova / c. / black holeb. / red giant / d. / nebula
____21.A star is said to be born when ____.
a. / a protostar reaches a temperature high enough for nuclear fusion to beginb. / a red giant collapses on itself and becomes a black hole
c. / pressure within a protostar becomes so great that a supernova occurs
d. / a dark, cool interstellar cloud begins to contract
____22.Which force is most responsible for the formation of a star?
a. / gravity / c. / interstellar forceb. / nuclear force / d. / electromagnetic force
____23.In the Milky Way, the most abundant gas in emission nebulae is ____.
a. / helium / c. / argonb. / hydrogen / d. / nitrogen
____24.Massive stars terminate in a brilliant explosion called a ____.
a. / red giant / c. / neutron starb. / protostar / d. / supernova
____25.Which stars are composed of matter in which electrons have combined with protons?
a. / black holes / c. / white dwarfsb. / black dwarfs / d. / neutron stars
____26.All stars, regardless of size, eventually ____.
a. / turn into black dwarfs / c. / run out of fuel and collapseb. / explode / d. / become black holes
____27.In the cores of extremely hot red giants, nuclear reactions convert helium to ____.
a. / carbon / c. / leadb. / hydrogen / d. / argon
____28.Before being engulfed, matter that is pulled into a black hole should become very hot and emit ____.
a. / infrared radiation / c. / atomsb. / hydrogen nuclei / d. / X-rays
____29.When a main-sequence star has exhausted the fuel in its core, it becomes a ____.
a. / black hole / c. / neutron starb. / black dwarf / d. / red giant
____30.The sun is a ____.
a. / black hole / c. / main-sequence starb. / black dwarf / d. / red giant
____31.What is the next stage in the sun’s life cycle?
a. / white dwarf / c. / planetary nebulab. / red giant / d. / black dwarf
____32.What will be the final stage in the sun’s life cycle?
a. / white dwarf / c. / planetary nebulab. / red giant / d. / black dwarf
____33.Light cannot escape the intense gravitational pull of a ____.
a. / black hole / c. / main-sequence starb. / black dwarf / d. / red giant
____34.Our galaxy is called the ____.
a. / Local Group / c. / Andromedab. / Orion / d. / Milky Way
____35.At its nucleus, the Milky Way Galaxy is about 100,000 light-years wide and ____.
a. / 1,000 light-years thick / c. / 100,000 light-years thickb. / 10,000 light-years thick / d. / 1,000,000 light-years thick
____36.Where is our sun located in the Milky Way?
a. / within one of the spiral armsb. / at the exact center of the galactic nucleus
c. / in the galactic halo
d. / at the tip of one of the spiral arms
____37.About 60 percent of all known galaxies are classified as ____.
a. / spiral galaxies / c. / irregular galaxiesb. / elliptical galaxies / d. / binary systems
____38.Which object is largest?
a. / globular cluster / c. / starb. / galaxy / d. / planet
____39.Which of the following is NOT a type of galaxy?
a. / nebular / c. / spiralb. / irregular / d. / elliptical
____40.According to Hubble’s law, galaxies are retreating at a speed that is proportional to their ____.
a. / orientation / c. / galactic positionb. / distance / d. / mass
____41.Which of the following indicates that the universe is expanding?
a. / red shift of distant galaxiesb. / red shift of the galaxies in the Local Group
c. / blue shift of distant galaxies
d. / blue shift of the Milky Way
____42.Based on the observed red shifts in the spectral lines of distant galaxies, astronomers conclude that____.
a. / Earth is in the center of the universeb. / the universe is contracting
c. / the universe is expanding
d. / the universe is smaller than once believed
____43.Greater red shifts in the spectra of galaxies indicate ____.
a. / faster speeds / c. / higher temperaturesb. / slower speeds / d. / lower temperatures
____44.According to the big bang theory, the universe began about ____.
a. / 4.5 billion years ago / c. / 49.6 billion years agob. / 13.7 billion years ago / d. / 130 billion years ago
____45.Which of the following supports the big bang theory?
a. / pulsars / c. / galactic clustersb. / cosmic background radiation / d. / irregular galaxies
Completion
Complete each sentence or statement.
46.Patterns of stars called ______were originally named in honor of mythological characters or great heroes.
47.The most basic way to measure the distance to a star is ______.
48.A light-year is the distance ______travels in a year.
49.Apparent magnitude refers to a star’s ______as it appears from ______.
50.Some stars, called ______, get brighter and fainter in a regular pattern.
51.A(n) ______is a developing star not yet hot enough to engage in nuclear fusion.
52.Stars that radiate short pulses of radio energy are called ______.
53.The most dense stars known to exist are called ______.
54.The average star spends ______percent of its life as a hydrogen-burning, main-sequence star.
55.The sun is positioned about ______of the way from the center of the galaxy.
56.The Milky Way is classified as a(n) ______galaxy.
57.In addition to size and shape, one of the major differences among galaxies is the ______of their stars.
58.A(n) ______galaxy is a type of galaxy that lacks symmetry.
59.The apparent change in wavelength of radiation caused by the relative motions of the source and the observer is called the ______.
60.The ______, which occurred in an instant, marks the beginning of the universe.
Short Answer
61.Which property of a star can be determined by its color?
62.What is parallax?
63.Which factors determine a star’s apparent magnitude?
64.What are the two main types of bright nebulae?
65.How hot must the core of a protostar be to begin nuclear fusion?
66.Describe what is happening to the star shown in Figure 25-2.
67.What type of star is shown in Figure 25-2?
68.What happens to a low-mass star when it depletes its hydrogen fuel?
69.Why do massive stars age faster than stars that are less massive?
70.Why does a red giant have a reddish appearance?
71.What is a galaxy?
72.What type of galaxy is composed mainly of young stars?
73.State Hubble’s law in your own words.
74.What will happen to the universe if its average density is less than its critical density?
Essay
75.Describe each step of the sun’s life cycle.
76.According to the big bang theory, how did the universe begin? What had to happen before atoms could form?