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Chapter 16 Clickers
Astronomy: A Beginner’s
Guide to the Universe
Seventh Edition
Galaxies and
Dark Matter
© 2013 Pearson Education, Inc.
Question 1
Based on galactic rotation curves and motions in clusters of
galaxies, dark matter
a)
b)
c)
d)
e)
makes up about 90 percent of the matter in the universe.
is best detected by the largest optical telescopes.
makes up about 10 percent of the matter in clusters of galaxies.
exists but has no observable effects on galaxies.
is the result of gas and dust.
© 2013 Pearson Education, Inc.
Question 1
Based on galactic rotation curves and motions in clusters of
galaxies, dark matter
a)
b)
c)
d)
e)
makes up about 90 percent of the matter in the universe.
is best detected by the largest optical telescopes.
makes up about 10 percent of the matter in clusters of galaxies.
exists but has no observable effects on galaxies.
is the result of gas and dust.
© 2013 Pearson Education, Inc.
Question 2
Collisions between galaxies
a) are much rarer than collisions between stars.
b) can transform elliptical galaxies into spirals.
c) trigger Type II supernova explosions in the halo.
d) cause gas and dust clouds to collide, leading to
rapid star formation.
© 2013 Pearson Education, Inc.
Question 2
Collisions between galaxies
a) are much rarer than collisions between stars.
b) can transform elliptical galaxies into spirals.
c) trigger Type II supernova explosions in the halo.
d) cause gas and dust clouds to collide, leading to
rapid star formation.
Explanation:
Galaxies are relatively close
compared with their size. In
clusters of galaxies, collisions
clearly occur.
© 2013 Pearson Education, Inc.
Question 3
When spiral galaxies collide, the greatest impact
occurs on their
a) globular cluster stars.
b) giant molecular clouds.
c) central bulge stars.
d) open clusters.
e) disk stars.
© 2013 Pearson Education, Inc.
Question 3
When spiral galaxies collide, the greatest impact
occurs on their
a) globular cluster stars.
b) giant molecular clouds.
c) central bulge stars.
d) open clusters.
e) disk stars.
© 2013 Pearson Education, Inc.
Question 5
The rapid variation of brightness of quasars indicates
a) the source of energy is very small.
b) energy is coming from matter and antimatter.
c) the energy source is rotating rapidly.
d) a chain reaction of supernovas occurs.
e) there are many separate sources of energy in the core.
© 2013 Pearson Education, Inc.
Question 5
The rapid variation of brightness of quasars indicates
a) the source of energy is very small.
b) energy is coming from matter and antimatter.
c) the energy source is rotating rapidly.
d) a chain reaction of supernovas occurs.
e) there are many separate sources of energy in the core.
Explanation:
The size of an object cannot
be larger than the distance
light can travel in the time it
takes to change its brightness.
© 2013 Pearson Education, Inc.
Question 6
A galaxy seen 1 billion light-years away means we see it
a)
b)
c)
d)
as it was when the universe was 1 billion years old.
as it will be 1 billion years from now.
as it was 1 billion years ago.
as it is today, but redshifted 10
percent of the speed of light.
e) as it was just after the Big Bang.
© 2013 Pearson Education, Inc.
Question 6
A galaxy seen 1 billion light-years away means we see it
a)
b)
c)
d)
as it was when the universe was 1 billion years old.
as it will be 1 billion years from now.
as it was 1 billion years ago.
as it is today, but redshifted 10
percent of the speed of light.
e) as it was just after the Big Bang.
Explanation:
Looking farther away in space means
looking back further in time, to when the
object (and universe) was younger.
© 2013 Pearson Education, Inc.
Question 7
The large-scale distribution of galaxies in the universe
reveals
a) a smooth, continuous, and
homogeneous arrangement
of clusters.
b) large voids, with most
of the galaxies lying in
filaments and sheets.
c) a large supercluster at the
center of the universe.
d) a central void with walls of
galaxies at the edge of the
universe.
© 2013 Pearson Education, Inc.
Question 7
The large-scale distribution of galaxies in the universe
reveals
a) a smooth, continuous, and
homogeneous arrangement
of clusters.
b) large voids, with most
of the galaxies lying in
filaments and sheets.
c) a large supercluster at the
center of the universe.
d) a central void with walls of
galaxies at the edge of the
universe.
© 2013 Pearson Education, Inc.
Question 8
The lensing of a distant quasar is produced in a
foreground galaxy by its
a) total mass of stars, gas, and dark matter.
b) central supermassive black hole.
c) globular clusters.
d) magnetic fields.
e) intergalactic gas.
© 2013 Pearson Education, Inc.
Question 8
The lensing of a distant quasar is produced in a
foreground galaxy by its
a) total mass of stars, gas, and dark matter.
b) central supermassive black hole.
c) globular clusters.
d) magnetic fields.
e) intergalactic gas.
Explanation:
The twin quasar AC114 has
two images of the same object.
© 2013 Pearson Education, Inc.