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Chapter 20 Reading Quiz Clickers
The Cosmic Perspective Seventh Edition
© 2014 Pearson Education, Inc.
Galaxies and the Foundation of Modern Cosmology
Chapter 20
© 2014 Pearson Education, Inc.
20.1 Islands of Stars
• How are the lives of galaxies connected with the history of the universe?
• What are the three major types of galaxies? • How are galaxies grouped together?
Chapter 20
© 2014 Pearson Education, Inc.
Where in the universe do we see young galaxies?
a) in the Local Group b) in the Local Supercluster c) in all regions of space d) billions of light-years away
Chapter 20
© 2014 Pearson Education, Inc.
Where in the universe do we see young galaxies?
a) in the Local Group b) in the Local Supercluster c) in all regions of space d) billions of light-years away
Chapter 20
© 2014 Pearson Education, Inc.
Which of the following is not a key difference between elliptical and spiral galaxies?
a) Elliptical galaxies are seen at greater distances from the Milky Way.
b) Elliptical galaxies contain less dust and cool gas than spiral galaxies.
c) Elliptical galaxies are redder than spiral galaxies. d) Spiral galaxies have more young stars than elliptical
galaxies. e) Elliptical galaxies are generally smaller than spiral
galaxies.
Chapter 20
© 2014 Pearson Education, Inc.
Which of the following is not a key difference between elliptical and spiral galaxies?
a) Elliptical galaxies are seen at greater distances from the Milky Way.
b) Elliptical galaxies contain less dust and cool gas than spiral galaxies.
c) Elliptical galaxies are redder than spiral galaxies. d) Spiral galaxies have more young stars than elliptical
galaxies. e) Elliptical galaxies are generally smaller than spiral
galaxies.
Chapter 20
© 2014 Pearson Education, Inc.
What type of galaxy was more common when the universe was younger?
a) elliptical b) spiral c) irregular d) A and C e) B and C
Chapter 20
© 2014 Pearson Education, Inc.
What type of galaxy was more common when the universe was younger?
a) elliptical b) spiral c) irregular d) A and C e) B and C
Chapter 20
© 2014 Pearson Education, Inc.
Which of the following types of galaxy in Hubble's galaxy classification is a sphere?
a) S0 b) E0 c) SB0 d) E7 e) Sc
Chapter 20
© 2014 Pearson Education, Inc.
Which of the following types of galaxy in Hubble's galaxy classification is a sphere?
a) S0 b) E0 c) SB0 d) E7 e) Sc
Chapter 20
© 2014 Pearson Education, Inc.
Where are elliptical galaxies most likely to be found?
a) in the central regions of clusters b) on the outskirts of clusters c) in small clusters d) in between clusters
Chapter 20
© 2014 Pearson Education, Inc.
Where are elliptical galaxies most likely to be found?
a) in the central regions of clusters b) on the outskirts of clusters c) in small clusters d) in between clusters
Chapter 20
© 2014 Pearson Education, Inc.
20.2 Measuring Galactic Distances
• How do we measure the distances to galaxies? • How did Hubble prove that galaxies lie far beyond
the Milky Way? • What is Hubble's law?
Chapter 20
© 2014 Pearson Education, Inc.
Which of the following is not a standard candle?
a) A G2 star b) a Cepheid variable star with a measured period c) a white dwarf supernova d) a massive star supernova e) a spiral galaxy with a measured rotation speed
Chapter 20
© 2014 Pearson Education, Inc.
Which of the following is not a standard candle?
a) A G2 star b) a Cepheid variable star with a measured period c) a white dwarf supernova d) a massive star supernova e) a spiral galaxy with a measured rotation speed
Chapter 20
© 2014 Pearson Education, Inc.
Which of the following techniques or standard candles is used for measuring the largest distances?
a) Cepheid variables b) radar ranging c) main-sequence fitting d) parallax
Chapter 20
© 2014 Pearson Education, Inc.
Which of the following techniques or standard candles is used for measuring the largest distances?
a) Cepheid variables b) radar ranging c) main-sequence fitting d) parallax
Chapter 20
© 2014 Pearson Education, Inc.
What unit of distance is used in radar ranging?
a) the light-year b) the parsec c) the astronomical unit d) the kilometer
Chapter 20
© 2014 Pearson Education, Inc.
What unit of distance is used in radar ranging?
a) the light-year b) the parsec c) the astronomical unit d) the kilometer
Chapter 20
© 2014 Pearson Education, Inc.
Who participated in the Great Debate in 1920 about the scale of the universe?
a) Tully and Fisher b) Hubble and Einstein c) Hubble and Abel d) Curtis and Shapley e) Tully and Abel
Chapter 20
© 2014 Pearson Education, Inc.
Who participated in the Great Debate in 1920 about the scale of the universe?
a) Tully and Fisher b) Hubble and Einstein c) Hubble and Abel d) Curtis and Shapley e) Tully and Abel
Chapter 20
© 2014 Pearson Education, Inc.
Which of the following was an argument used by Shapley for a small universe?
a) Some spiral nebulae have measurable parallax. b) Main-sequence fitting showed some spiral nebulae
to be within the Milky Way. c) If spiral nebulae were galaxies, then the universe
would be improbably old. d) A nova in a spiral nebula was the same brightness
as novae in the Milky Way.
Chapter 20
© 2014 Pearson Education, Inc.
Which of the following was an argument used by Shapley for a small universe?
a) Some spiral nebulae have measurable parallax. b) Main-sequence fitting showed some spiral nebulae
to be within the Milky Way. c) If spiral nebulae were galaxies, then the universe
would be improbably old. d) A nova in a spiral nebula was the same
brightness as novae in the Milky Way.
Chapter 20
© 2014 Pearson Education, Inc.
How did Hubble show that the Andromeda Galaxy was, in fact, a distant galaxy?
a) He observed a white dwarf supernova in the galaxy.
b) He observed Cepheid variables in the galaxy. c) He measured the rotation speed of the galaxy. d) He observed the main-sequence of stars in a
cluster in the galaxy.
Chapter 20
© 2014 Pearson Education, Inc.
How did Hubble show that the Andromeda Galaxy was, in fact, a distant galaxy?
a) He observed a white dwarf supernova in the galaxy.
b) He observed Cepheid variables in the galaxy. c) He measured the rotation speed of the galaxy. d) He observed the main-sequence of stars in a
cluster in the galaxy.
Chapter 20
© 2014 Pearson Education, Inc.
What parameters do Hubble's law relate to each other?
a) galaxy rotation speed and luminosity b) galaxy classification and mass c) Cepheid star period and luminosity d) galaxy recession velocity and distance e) galaxy mass and distance
Chapter 20
© 2014 Pearson Education, Inc.
What parameters do Hubble's law relate to each other?
a) galaxy rotation speed and luminosity b) galaxy classification and mass c) Cepheid star period and luminosity d) galaxy recession velocity and distance e) galaxy mass and distance
Chapter 20
© 2014 Pearson Education, Inc.
What technique for measuring distance did Hubble use to discover Hubble's law?
a) Cepheid variables in galaxies b) redshifts of bright objects in galaxies c) white star supernovae in galaxies d) main-sequence fitting of clusters in galaxies
Chapter 20
© 2014 Pearson Education, Inc.
What technique for measuring distance did Hubble use to discover Hubble's law?
a) Cepheid variables in galaxies b) redshifts of bright objects in galaxies c) white star supernovae in galaxies d) main-sequence fitting of clusters in galaxies
Chapter 20
© 2014 Pearson Education, Inc.
20.3 The Age of the Universe
• How does Hubble's Law tell us the age of the universe?
• How does expansion affect distance measurements?
• Why does the observable universe have a horizon?
Chapter 20
© 2014 Pearson Education, Inc.
What is the Cosmological Principle?
a) Matter is evenly distributed throughout the universe. b) The rate of expansion of spacetime has been uniform
since the Big Bang. c) Hubble's constant has the same value at all locations in
the universe. d) The laws of physics are the same everywhere in the
universe.
Chapter 20
© 2014 Pearson Education, Inc.
What is the Cosmological Principle?
a) Matter is evenly distributed throughout the universe.
b) The rate of expansion of spacetime has been uniform since the Big Bang.
c) Hubble's constant has the same value at all locations in the universe.
d) The laws of physics are the same everywhere in the universe.
Chapter 20
© 2014 Pearson Education, Inc.
The inverse of Hubble's constant gives an estimate of
a) the size of the universe. b) the mass of the universe. c) the speed of light. d) whether or not the universe will expand forever. e) the age of the universe.
Chapter 20
© 2014 Pearson Education, Inc.
The inverse of Hubble's constant gives an estimate of
a) the size of the universe. b) the mass of the universe. c) the speed of light. d) whether or not the universe will expand forever. e) the age of the universe.
Chapter 20
© 2014 Pearson Education, Inc.
How does the expansion of the universe affect light?
a) There is no effect. Its speed and wavelength are unchanged.
b) It causes the speed of light to gradually decrease. c) It causes the speed of light to gradually increase. d) It causes the wavelength of light to increase. e) It causes the wavelength of light to decrease.
Chapter 20
© 2014 Pearson Education, Inc.
How does the expansion of the universe affect light?
a) There is no effect. Its speed and wavelength are unchanged.
b) It causes the speed of light to gradually decrease. c) It causes the speed of light to gradually increase. d) It causes the wavelength of light to increase. e) It causes the wavelength of light to decrease.
Chapter 20
© 2014 Pearson Education, Inc.
How do we define the horizon of the observable universe?
a) It is the point past which there are no more galaxies, just empty space.
b) It defines the half of the sky which we cannot see because of our position on the Earth.
c) It is a point in space exactly 14 billion light-years away in every direction.
d) It is the limit which represents looking back to the beginning of the universe.
Chapter 20
© 2014 Pearson Education, Inc.
How do we define the horizon of the observable universe?
a) It is the point past which there are no more galaxies, just empty space.
b) It defines the half of the sky which we cannot see because of our position on the Earth.
c) It is a point in space exactly 14 billion light-years away in every direction.
d) It is the limit which represents looking back to the beginning of the universe.