Download Suppose you tried to determine where we are in the galaxy by

Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Suppose you tried to determine where we are
in the galaxy by looking in different directions
to see how many stars you could see. If you did
this, you would pinpoint our location
Suppose you tried to determine where we are
in the galaxy by looking in different directions
to see how many stars you could see. If you did
this, you would pinpoint our location
Why does a simple survey, such as described
in the previous slide, give a FALSE answer?
Why does a simple survey, such as described
in the previous slide, give a FALSE answer?
a)  in the center of the galaxy.
b)  in an arm of the galaxy.
c)  near the edge of the galaxy.
a)  in the center of the galaxy.
b)  in an arm of the galaxy.
c)  near the edge of the galaxy.
a)  We can't count enough stars to get a good result.
b)  Interstellar dust blocks our view.
c)  Black holes distort the light from distant regions,
giving a false result.
d)  Light from far-away stars that have died block our
view, giving a false result.
a)  We can't count enough stars to get a good result.
b)  Interstellar dust blocks our view.
c)  Black holes distort the light from distant regions,
giving a false result.
d)  Light from far-away stars that have died block our
view, giving a false result.
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© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Since dust scatters blue light more than red,
stars seen through a lot of interstellar dust
would look
Since dust scatters blue light more than red,
stars seen through a lot of interstellar dust
would look
Why is it difficult to get a good picture of what
the Milky Way Galaxy looks like?
Why is it difficult to get a good picture of what
the Milky Way Galaxy looks like?
a)  bluer than expected for their spectral type.
b)  redder than expected for their spectral type.
c)  the same as when seen without dust.
a)  bluer than expected for their spectral type.
b)  redder than expected for their spectral type.
c)  the same as when seen without dust.
a)  We're in the middle of one of its arms and thus have no
perspective.
b)  It is very large and the edges are far away and faint.
c)  Dust blocks our view when we look toward the center
or in the disk.
d)  We cannot see it from the outside.
e)  all of the above
a)  We're in the middle of one of its arms and thus have no
perspective.
b)  It is very large and the edges are far away and faint.
c)  Dust blocks our view when we look toward the center
or in the disk.
d)  We cannot see it from the outside.
e)  all of the above
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© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
How do we get a good picture of what our
Milky Way galaxy looks like?
How do we get a good picture of what our
Milky Way galaxy looks like?
About how long does light take to reach us from
the nearest star besides the Sun? (The Sun
takes 8 minutes.)
About how long does light take to reach us from
the nearest star besides the Sun? (The Sun
takes 8 minutes.)
a)  by using infrared or microwaves to penetrate the dust
b)  by using radio telescopes to see where clouds of
hydrogen gas are
c)  by taking photos from both the top and side of the
galaxy to get a good view
d)  all of the above
e)  A and B
a)  by using infrared or microwaves to penetrate the dust
b)  by using radio telescopes to see where clouds of
hydrogen gas are
c)  by taking photos from both the top and side of the
galaxy to get a good view
d)  all of the above
e)  A and B
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
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© 2014 Pearson Education, Inc.
about an hour
about a week
about a month
about four years
about 1000 years
© 2014 Pearson Education, Inc.
about an hour
about a week
about a month
about four years
about 1000 years
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Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
About how long does light take to cross the
Milky Way Galaxy?
About how long does light take to cross the
Milky Way Galaxy?
What does our galaxy look like?
What does our galaxy look like?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a)  It has a large disk with spiral arms, and is relatively flat
and thin.
b)  It has clouds of gas and dust in the spiral arms.
c)  Older yellow stars are found mostly in the central bulge.
d)  Old stars and globular clusters are located in a
spherical halo above and below the disk.
e)  all of the above
a)  It has a large disk with spiral arms, and is relatively flat
and thin.
b)  It has clouds of gas and dust in the spiral arms.
c)  Older yellow stars are found mostly in the central bulge.
d)  Old stars and globular clusters are located in a
spherical halo above and below the disk.
e)  all of the above
about a month
about four years
about 1000 years
about 100,000 years
millions of years
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about a month
about four years
about 1000 years
about 100,000 years
millions of years
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
We can estimate the mass of our galaxy by
We can estimate the mass of our galaxy by
When you calculate the Milky Way's mass
using the two methods of the previous
slide, what do you find?
When you calculate the Milky Way's mass
using the two methods of the previous
slide, what do you find?
a)  counting all the stars and multiplying by the average
mass of a star.
b)  making an estimate of the number of stars and multiplying
by the average mass of a star, then accounting for gas and
dust.
c)  observing the speed of rotation using the Doppler
shift, knowing the orbital size and speed to calculate
mass with Kepler's law.
d)  A and C
e)  B and C
a)  counting all the stars and multiplying by the average
mass of a star.
b)  making an estimate of the number of stars and multiplying
by the average mass of a star, then accounting for gas and
dust.
c)  observing the speed of rotation using the Doppler
shift, knowing the orbital size and speed to calculate
mass with Kepler's law.
d)  A and C
a)  They agree pretty well.
b)  The mass you estimate for all the visible stars is
only about 1/10 the mass you get from observing
motions.
c)  The mass you estimate for all the visible stars is
about 10 times the mass you get from observing
motions.
a)  They agree pretty well.
b)  The mass you estimate for all the visible stars is
only about 1/10 the mass you get from observing
motions.
c)  The mass you estimate for all the visible stars is
about 10 times the mass you get from observing
motions.
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e)  B and C
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© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
How do astronomers interpret the results of the
previous slide?
How do astronomers interpret the results of the
previous slide?
Gas is added to the interstellar medium by
supernovae and planetary nebulae. What kind
of gas would you expect that to be?
Gas is added to the interstellar medium by
supernovae and planetary nebulae. What kind
of gas would you expect that to be?
a) 
b) 
c) 
d) 
a) 
b) 
c) 
d) 
a)  hydrogen gas
b)  helium gas
c)  gas that has a mix of heavier elements in it, such
as carbon, oxygen, silicon, iron, etc
a)  hydrogen gas
b)  helium gas
c)  gas that has a mix of heavier elements in it,
such as carbon, oxygen, silicon, iron, etc
Astronomers are bad estimators.
We don't know the masses of stars well.
90% of the galaxy is hidden from view.
There must be some other kind of matter in the
galaxy that we cannot see.
e)  C and D
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Astronomers are bad estimators.
We don't know the masses of stars well.
90% of the galaxy is hidden from view.
There must be some other kind of matter in the
galaxy that we cannot see.
e)  C and D
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© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Stars we see in the halo of our galaxy formed
even before the Milky Way collapsed into a
disk. Since we see them today, they must be
Stars we see in the halo of our galaxy formed
even before the Milky Way collapsed into a
disk. Since we see them today, they must be
Why do stars in the halo of the galaxy have
almost no heavy elements such as carbon,
nitrogen, and oxygen?
Why do stars in the halo of the galaxy have
almost no heavy elements such as carbon,
nitrogen, and oxygen?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a)  Those elements have been used up in halo stars.
b)  Heavy elements are biological, and there is no life
out there to make them.
c)  Halo stars formed before those elements were
made.
d)  Making C, N, and O requires massive stars, and
there are no massive stars in the halo.
a)  Those elements have been used up in halo stars.
b)  Heavy elements are biological, and there is no life
out there to make them.
c)  Halo stars formed before those elements were
made.
d)  Making C, N, and O requires massive stars, and
there are no massive stars in the halo.
young.
old.
low mass.
high mass.
B and C
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young.
old.
low mass.
high mass.
B and C
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© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Halo stars
Halo stars
Where do stars form in the galaxy today?
Where do stars form in the galaxy today?
a)  are deficient in common elements such as carbon,
nitrogen, oxygen, and iron.
b)  have orbits that plunge through the plane of the
galaxy.
c)  are all more massive than the Sun.
d)  all of the above
e)  A and B
a)  are deficient in common elements such as carbon,
nitrogen, oxygen, and iron.
b)  have orbits that plunge through the plane of the
galaxy.
c)  are all more massive than the Sun.
d)  all of the above
e)  A and B
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
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© 2014 Pearson Education, Inc.
No stars are forming in the galaxy today.
molecular clouds
dark dust clouds
glowing ionization nebulae
B, C, and D
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No stars are forming in the galaxy today.
molecular clouds
dark dust clouds
glowing ionization nebulae
B, C, and D
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
How do the elements produced in massive
stars get into other stars?
How do the elements produced in massive
stars get into other stars?
Infrared telescopes penetrate dust and show
us that stars at the center of the Milky Way
are orbiting very fast. Why?
Infrared telescopes penetrate dust and show
us that stars at the center of the Milky Way
are orbiting very fast. Why?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a)  They are in the process of forming.
b)  They are being accelerated by a supernova
explosion.
c)  There is probably a massive black hole at our
galaxy's center.
a)  They are in the process of forming.
b)  They are being accelerated by a supernova
explosion.
c)  There is probably a massive black hole at our
galaxy's center.
Supernovae blow them out into space.
Red giant winds blow them into space.
The star-gas-star cycle circulates them.
all of the above
A and B
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Supernovae blow them out into space.
Red giant winds blow them into space.
The star-gas-star cycle circulates them.
all of the above
A and B
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© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Based on the idea of chemical enrichment,
which types of stars contain a higher proportion
of heavy elements: stars in globular clusters or
stars in open clusters?
Based on the idea of chemical enrichment,
which types of stars contain a higher proportion
of heavy elements: stars in globular clusters or
stars in open clusters?
What causes the blue and red colors in a
photograph of a typical nebula?
What causes the blue and red colors in a
photograph of a typical nebula?
a)  Stars in globular clusters, because they are younger and
therefore formed from more enriched material.
b)  Stars in globular clusters, because they are older and
therefore formed from more enriched material.
c)  Stars in open clusters, because they are younger and
therefore formed from more enriched material.
d)  Stars in open clusters, because they are older and
therefore formed from more enriched material.
a)  Stars in globular clusters, because they are younger and
therefore formed from more enriched material.
b)  Stars in globular clusters, because they are older and
therefore formed from more enriched material.
c)  Stars in open clusters, because they are younger and
therefore formed from more enriched material.
d)  Stars in open clusters, because they are older and
therefore formed from more enriched material.
a)  The ionizing photons from a hot star cause hydrogen gas to glow
red and helium to glow blue.
b)  Dust grains scatter blue light and let red light pass through,
similar to the blue sky and red sunsets in our atmosphere.
c)  The blue color is due to the scattering of light by interstellar dust
grains and the red color arises from hydrogen emissions.
d)  The blue light comes from young, hot stars and the red light from
older, cooler stars.
e)  The blue color comes from gas moving toward us and the red color
from gas moving away from us.
a)  The ionizing photons from a hot star cause hydrogen gas to glow
red and helium to glow blue.
b)  Dust grains scatter blue light and let red light pass through,
similar to the blue sky and red sunsets in our atmosphere.
c)  The blue color is due to the scattering of light by interstellar
dust grains and the red color arises from hydrogen emissions.
d)  The blue light comes from young, hot stars and the red light from
older, cooler stars.
e)  The blue color comes from gas moving toward us and the red color
from gas moving away from us.
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Chapter 19 - 22
© 2014 Pearson Education, Inc.
Chapter 19 - 22
True or False?: Many spectacular ionization
nebulae are seen throughout the Milky Way's
halo.
True or False?: Many spectacular ionization
nebulae are seen throughout the Milky Way's
halo.
a)  True, they are the sites of new star formation.
b)  True, but they are concentrated in the spiral arms.
c)  False, there are no young, hot stars to cause
ionization nebulae in the halo.
d)  False, there are very few stars in the halo.
e)  False, there is very little mass in the halo.
a)  True, they are the sites of new star formation.
b)  True, but they are concentrated in the spiral arms.
c)  False, there are no young, hot stars to cause
ionization nebulae in the halo.
d)  False, there are very few stars in the halo.
e)  False, there is very little mass in the halo.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
True or False?: The Sun's velocity around the
Milky Way tells us that most of our galaxy's
dark matter lies within the Sun's orbit.
True or False?: The Sun's velocity around the
Milky Way tells us that most of our galaxy's
dark matter lies within the Sun's orbit.
a)  True, the Sun's motion in the galaxy shows that we are near
the edge of the Milky Way disk and therefore exterior to most of the
mass of the galaxy.
b)  True, the Milky Way's rotation curve stops increasing well before
the orbit of the Sun, indicating that the majority of the Milky Way's
mass lies within the Sun's orbit.
c)  False, the Milky Way's rotation curve remains flat well beyond the
orbit of the Sun, indicating that the majority of the Milky Way's
mass lies beyond the Sun's orbit.
d)  False, the Milky Way's rotation curve looks similar to the rotation
curve of planets in our solar system where most of the mass lies
near the center.
a)  True, the Sun's motion in the galaxy shows that we are near
the edge of the Milky Way disk and therefore exterior to most of the
mass of the galaxy.
b)  True, the Milky Way's rotation curve stops increasing well before
the orbit of the Sun, indicating that the majority of the Milky Way's
mass lies within the Sun's orbit.
c)  False, the Milky Way's rotation curve remains flat well beyond
the orbit of the Sun, indicating that the majority of the Milky
Way's mass lies beyond the Sun's orbit.
d)  False, the Milky Way's rotation curve looks similar to the rotation
curve of planets in our solar system where most of the mass lies
near the center.
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© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Which type of galaxies have a disk, bulge,
and halo?
Which type of galaxies have a disk, bulge,
and halo?
Which type of galaxies lack a disk?
Which type of galaxies lack a disk?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
spiral
elliptical
irregular
barred spiral
A and D
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spiral
elliptical
irregular
barred spiral
A and D
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spiral
elliptical
irregular
barred spiral
B and C
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spiral
elliptical
irregular
barred spiral
B and C
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Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Which type of galaxy contains a high
percentage of cool interstellar gas and dust?
Which type of galaxy contains a high
percentage of cool interstellar gas and dust?
Which type of galaxy contains little cool
interstellar gas and dust?
Which type of galaxy contains little cool
interstellar gas and dust?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
spiral
elliptical
irregular
barred spiral
All but B
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spiral
elliptical
irregular
barred spiral
All but B
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spiral
elliptical
irregular
barred spiral
All but B
© 2014 Pearson Education, Inc.
spiral
elliptical
irregular
barred spiral
All but B
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Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Which type of galaxy is particularly
common in clusters of galaxies?
Which type of galaxy is particularly
common in clusters of galaxies?
What is a standard candle?
What is a standard candle?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a)  a candle of known brightness
b)  a galaxy of known brightness
c)  any object whose luminosity is known
independently from its apparent brightness
d)  a star made of the same elements as the Sun
e)  a star with the same composition as a halo star
a)  a candle of known brightness
b)  a galaxy of known brightness
c)  any object whose luminosity is known
independently from its apparent brightness
d)  a star made of the same elements as the Sun
e)  a star with the same composition as a halo star
spiral
elliptical
irregular
barred spiral
All but B
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spiral
elliptical
irregular
barred spiral
All but B
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
What standard candle is useful at the
greatest distances?
What standard candle is useful at the
greatest distances?
What did astronomers debate about the
nature of spiral nebulae until the 1920s?
What did astronomers debate about the
nature of spiral nebulae until the 1920s?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a)  whether they were nebulae located in the Milky
Way, or spiral galaxies located far outside our
galaxy
b)  whether they were forming planets or stars
c)  both of the above
d)  none of the above
a)  whether they were nebulae located in the Milky
Way, or spiral galaxies located far outside our
galaxy
b)  whether they were forming planets or stars
c)  both of the above
d)  none of the above
main sequence stars
Cepheid variables
a star whose distance is known from parallax
white dwarf supernovae
None of the above
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main sequence stars
Cepheid variables
a star whose distance is known from parallax
white dwarf supernovae
None of the above
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© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
How did Edwin Hubble prove that the
spiral nebulae were distant galaxies?
How did Edwin Hubble prove that the
spiral nebulae were distant galaxies?
What is Hubble's Law?
What is Hubble's Law?
a)  He measured their parallax.
b)  He measured their Doppler shifts
c)  He found Cepheid variables in them that looked
pretty bright.
d)  He found Cepheid variables in them that looked
very faint.
a)  He measured their parallax.
b)  He measured their Doppler shifts
c)  He found Cepheid variables in them that looked
pretty bright.
d)  He found Cepheid variables in them that looked
very faint.
a)  The faster a galaxy is moving away, the farther
away it is.
b)  The farther away a galaxy is, the slower it is
moving away.
c)  All galaxies are getting closer together over time.
d)  Galaxies are expanding over time, with their stars
growing farther and farther apart.
a)  The faster a galaxy is moving away, the farther
away it is.
b)  The farther away a galaxy is, the slower it is
moving away.
c)  All galaxies are getting closer together over time.
d)  Galaxies are expanding over time, with their stars
growing farther and farther apart.
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© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
If faster galaxies are farther away, and there
is a direct proportion between speed and
distance, then
If faster galaxies are farther away, and there
is a direct proportion between speed and
distance, then
How do scientists estimate the age of the
universe?
How do scientists estimate the age of the
universe?
a)  all galaxies must be avoiding ours.
b)  all galaxies must have begun moving apart at the
same place and time.
c)  our galaxy must be in the center of the universe.
a)  all galaxies must be avoiding ours.
b)  all galaxies must have begun moving apart at
the same place and time.
c)  our galaxy must be in the center of the universe.
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a)  They take the distance to a nearby galaxy and divide it by
its speed of recession (time = distance/velocity).
b)  They take the distance to a very distant galaxy and divide
it by its speed of recession (time = distance/velocity).
c)  They take the distance to any galaxy and divide it by its
speed of recession (time = distance/velocity).
© 2014 Pearson Education, Inc.
a)  They take the distance to a nearby galaxy and divide it by
its speed of recession (time = distance/velocity).
b)  They take the distance to a very distant galaxy and divide
it by its speed of recession (time = distance/velocity).
c)  They take the distance to any galaxy and divide it by
its speed of recession (time = distance/velocity).
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Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Is measuring the speed of a receding galaxy a
complex scientific process?
Is measuring the speed of a receding galaxy a
complex scientific process?
What does it mean to say that our universe is
expanding?
What does it mean to say that our universe is
expanding?
a)  Yes, we're talking about cosmology and the edge of
the universe.
b)  No, it's just the Doppler shift–the shifting of
spectrum lines.
c)  No, it's the same principle police use to give you a
speeding ticket.
d)  B and C
a)  Yes, we're talking about cosmology and the edge of
the universe.
b)  No, it's just the Doppler shift–the shifting of
spectrum lines.
c)  No, it's the same principle police use to give you a
speeding ticket.
d)  B and C
a)  Galaxies are moving apart through space.
b)  Space itself is expanding.
c)  Everything is expanding, including galaxies, star
clusters, and star systems.
a)  Galaxies are moving apart through space.
b)  Space itself is expanding.
c)  Everything is expanding, including galaxies, star
clusters, and star systems.
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© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
When we look at a very distant galaxy, billions
of light years away, we see it
When we look at a very distant galaxy, billions
of light years away, we see it
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
when it was younger.
when it was older.
when the whole universe was younger.
when the whole universe was older.
A and C
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when it was younger.
when it was older.
when the whole universe was younger.
when the whole universe was older.
A and C
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© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
What do we see when we look beyond the
cosmological horizon?
What do we see when we look beyond the
cosmological horizon?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
Galaxies that are just about to form.
Galaxies that are about to enter the universe.
White dwarfs that are about to go supernova.
The beginning of the universe.
We cannot look beyond the cosmological horizon
because we cannot look back to a time before
the universe began.
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Galaxies that are just about to form.
Galaxies that are about to enter the universe.
White dwarfs that are about to go supernova.
The beginning of the universe.
We cannot look beyond the cosmological
horizon because we cannot look back to a time
before the universe began.
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Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
True or False? If you want to find elliptical
galaxies, you'll have better luck looking in
clusters of galaxies than elsewhere in the
universe.
True or False? If you want to find elliptical
galaxies, you'll have better luck looking in
clusters of galaxies than elsewhere in the
universe.
True or False?: If the standard candles you are
using are less luminous than you think they are,
then the distances you determine from them
will be too small.
True or False?: If the standard candles you are
using are less luminous than you think they are,
then the distances you determine from them
will be too small.
a)  True, galaxy clusters have a much higher
percentage of elliptical galaxies than do other
parts of the universe.
b)  True, elliptical galaxies are found exclusively in galaxy
clusters.
c)  False, elliptical galaxies are more commonly found away
from galaxy clusters.
d)  False, elliptical galaxies are never found in galaxy clusters.
e)  False, you would have an equal chance of finding an elliptical
galaxy in any environment in the universe.
a)  True, galaxy clusters have a much higher
percentage of elliptical galaxies than do other
parts of the universe.
b)  True, elliptical galaxies are found exclusively in galaxy
clusters.
c)  False, elliptical galaxies are more commonly found away
from galaxy clusters.
d)  False, elliptical galaxies are never found in galaxy clusters.
e)  False, you would have an equal chance of finding an elliptical
galaxy in any environment in the universe.
a)  True, because they are less luminous, they are further away.
b)  False, because they are less luminous, they are closer than
you think and your distance determination is too large.
c)  False, standard candles produce the same measurement
at the telescope no matter what distance they are.
d)  It depends on the standard candle: if they are Cepheid
variables, they will still pulsate at the same rate no
matter what distance they are from you.
a)  True, because they are less luminous, they are further away.
b)  False, because they are less luminous, they are closer
than you think and your distance determination is too
large.
c)  False, standard candles produce the same measurement
at the telescope no matter what distance they are.
d)  It depends on the standard candle: if they are Cepheid
variables, they will still pulsate at the same rate no
matter what distance they are from you.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Galaxy A is moving away twice as fast as
Galaxy B, so Galaxy A must be
Galaxy A is moving away twice as fast as
Galaxy B, so Galaxy A must be
When we look at the farthest galaxies in the
Hubble Ultra Deep Field, we see galaxies
that are
When we look at the farthest galaxies in the
Hubble Ultra Deep Field, we see galaxies
that are
a) 
b) 
c) 
d) 
a) 
b) 
c) 
d) 
a) 
b) 
c) 
d) 
a) 
b) 
c) 
d) 
twice as far away as Galaxy B.
twice as close as Galaxy B.
four times as far away as Galaxy B.
four times as close as Galaxy B.
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twice as far away as Galaxy B.
twice as close as Galaxy B.
four times as far away as Galaxy B.
four times as close as Galaxy B.
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about 12 or 13 billion years old.
about 4.5 billion years old.
about 1 or 2 billion years old.
about 4 million years old.
© 2014 Pearson Education, Inc.
about 12 or 13 billion years old.
about 4.5 billion years old.
about 1 or 2 billion years old.
about 4 million years old.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
What are possible reasons that galaxies
differ in form?
What are possible reasons that galaxies
differ in form?
What is likely to happen if two galaxies collide?
What is likely to happen if two galaxies collide?
a)  Pre-galactic clouds have different densities.
b)  Pre-galactic clouds have different rotation rates.
c)  Galaxies collide with one another, creating different
types.
d)  all of the above.
e)  A and B
a)  Pre-galactic clouds have different densities.
b)  Pre-galactic clouds have different rotation rates.
c)  Galaxies collide with one another, creating different
types.
d)  all of the above.
e)  A and B
a)  Their stars will crash into each other.
b)  Their mutual gravitational pull will greatly distort
each galaxy.
c)  Starbursts–greatly enhanced star formation–may
occur.
d)  all of the above
e)  B and C
a)  Their stars will crash into each other.
b)  Their mutual gravitational pull will greatly distort
each galaxy.
c)  Starbursts–greatly enhanced star formation–may
occur.
d)  all of the above
e)  B and C
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
What is found at the centers of many galaxies?
What is found at the centers of many galaxies?
Why should we not be surprised that galaxy
collisions were common in the past?
Why should we not be surprised that galaxy
collisions were common in the past?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a)  Galaxies moved faster in the past and therefore collided
more often.
b)  Galaxies were larger in the past and therefore collided
more often.
c)  The universe was much denser in the past, so its
galaxies were much closer together, making collisions
much more frequent.
d)  Because elliptical galaxies are formed by the collision of
two spiral galaxies, ellipticals are observed to be more
common in the past.
a)  Galaxies moved faster in the past and therefore collided
more often.
b)  Galaxies were larger in the past and therefore collided
more often.
c)  The universe was much denser in the past, so its
galaxies were much closer together, making
collisions much more frequent.
d)  Because elliptical galaxies are formed by the collision of
two spiral galaxies, ellipticals are observed to be more
common in the past.
a large central star
a large central planet
a cluster of stars
a supermassive black hole
a supernova
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a large central star
a large central planet
a cluster of stars
a supermassive black hole
a supernova
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
True or False?: Starburst galaxies have been
forming stars at the same furious pace since
the universe was about a billion years old.
True or False?: Starburst galaxies have been
forming stars at the same furious pace since
the universe was about a billion years old.
Starburst galaxies have lots of gas and dust
that hides their star formation. For this reason,
Starburst galaxies have lots of gas and dust
that hides their star formation. For this reason,
a)  True, starburst galaxies are the most prolific regions
of star formation in the universe.
b)  False, after too many stars form, a black hole results
and a galaxy stops forming stars.
c)  False, the bursts of star formation would use up all the
gas in a galaxy in a much shorter period of time than
the age of the universe.
d)  False, starburst galaxies are only found nearby, and are
all very young.
a)  True, starburst galaxies are the most prolific regions
of star formation in the universe.
b)  False, after too many stars form, a black hole results
and a galaxy stops forming stars.
c)  False, the bursts of star formation would use up all the
gas in a galaxy in a much shorter period of time than
the age of the universe.
d)  False, starburst galaxies are only found nearby, and are
all very young.
a)  we're not really sure how much star formation is
occurring.
b)  we use infrared observations to penetrate the dust.
c)  we look for x-rays from very hot gas powered by
many supernovae.
d)  all of the above
e)  B and C
a)  we're not really sure how much star formation is
occurring.
b)  we use infrared observations to penetrate the dust.
c)  we look for x-rays from very hot gas powered by
many supernovae.
d)  all of the above
e)  B and C
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Matter falling into supermassive black holes
in the centers of galaxies is thought to be the
source of
Matter falling into supermassive black holes
in the centers of galaxies is thought to be the
source of
Where does the energy released by a massive
black hole come from?
Where does the energy released by a massive
black hole come from?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
jets that shoot far into space.
active galactic nuclei.
strong radio emissions.
quasars.
all of the above
© 2014 Pearson Education, Inc.
Chapter 19 - 22
jets that shoot far into space.
active galactic nuclei.
strong radio emissions.
quasars.
all of the above
© 2014 Pearson Education, Inc.
supernovas
gravity
colliding stars near the black hole
nuclear energy
none of the above
© 2014 Pearson Education, Inc.
supernovas
gravity
colliding stars near the black hole
nuclear energy
none of the above
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
True or False?: The black hole at the center of
our own galaxy may once have powered an
active galactic nucleus.
True or False?: The black hole at the center of
our own galaxy may once have powered an
active galactic nucleus.
Could Newton laws or Kepler's 3rd law be
applied to the hot gas orbiting the nucleus of
M87 to determine the mass of the central black
hole?
Could Newton laws or Kepler's 3rd law be
applied to the hot gas orbiting the nucleus of
M87 to determine the mass of the central black
hole?
a)  True, active nuclei in other galaxies appear to be
powered by accretion into similar sized black holes.
b)  True, the Milky Way has a very similar appearance to
other galaxies with active nuclei.
c)  False, the Milky Way is a spiral galaxy and only elliptical
galaxies have active nuclei.
d)  False, active nuclei in galaxies are only found in the
distant universe.
a)  True, active nuclei in other galaxies appear to be
powered by accretion into similar sized black holes.
b)  True, the Milky Way has a very similar appearance to
other galaxies with active nuclei.
c)  False, the Milky Way is a spiral galaxy and only elliptical
galaxies have active nuclei.
d)  False, active nuclei in galaxies are only found in the
distant universe.
a)  No, those laws apply to planets.
b)  Yes.
a)  No, those laws apply to planets.
b)  Yes.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Since quasars are mostly found at very great
distances,
Since quasars are mostly found at very great
distances,
What do we know about the beginning of the
universe?
What do we know about the beginning of the
universe?
a)  there must have been more of them when the
universe was young.
b)  we can use their light to study the intergalactic
medium between us and them.
c)  they must have remained unchanged for at least 10
billion years.
d)  all of the above
e)  A and B
a)  there must have been more of them when the
universe was young.
b)  we can use their light to study the intergalactic
medium between us and them.
c)  they must have remained unchanged for at least 10
billion years.
d)  all of the above
e)  A and B
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
It was about 6000 years ago.
It was billions of years ago.
It was extremely hot and dense.
A and C
B and C
© 2014 Pearson Education, Inc.
It was about 6000 years ago.
It was billions of years ago.
It was extremely hot and dense.
A and C
B and C
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
At the beginning of the universe,
At the beginning of the universe,
What observed feature of the universe
motivated scientists to propose the big bang
theory?
What observed feature of the universe
motivated scientists to propose the big bang
theory?
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a)  There is lots of debris in space, as would be
expected from an explosion.
b)  The universe is expanding, and the expansion must
trace back to a specific point and time of origin in
the past.
c)  Everything has a beginning, middle, and end.
a)  There is lots of debris in space, as would be
expected from an explosion.
b)  The universe is expanding, and the expansion
must trace back to a specific point and time of
origin in the past.
c)  Everything has a beginning, middle, and end.
the temperature was billions of degrees.
the density was enormously high.
matter could turn into energy and vice versa.
all of the above
A and B
© 2014 Pearson Education, Inc.
the temperature was billions of degrees.
the density was enormously high.
matter could turn into energy and vice versa.
all of the above
A and B
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
What does the big bang theory predict can
be seen today if there really was a big bang?
What does the big bang theory predict can
be seen today if there really was a big bang?
Which of the two main predictions of the big
bang theory turned out to be true?
Which of the two main predictions of the big
bang theory turned out to be true?
a)  Radiation from the big bang might be detected. It was
gamma rays 14 billion years ago, but today it is cooler and
would look like weak microwaves coming from all of space.
b)  The Big Bang produced three elements, which might be
seen in the oldest stars: 75% hydrogen, 25% helium, 1 part
in a billion lithium.
c)  The universe must be finite in mass and dimension.
d)  all of the above
e)  A and B
a)  Radiation from the big bang might be detected. It was
gamma rays 14 billion years ago, but today it is cooler and
would look like weak microwaves coming from all of space.
b)  The Big Bang produced three elements, which might be
seen in the oldest stars: 75% hydrogen, 25% helium, 1 part
in a billion lithium.
c)  The universe must be finite in mass and dimension.
d)  all of the above
e)  A and B
a)  Radiation has been found coming from all of space,
just as predicted.
b)  The oldest stars are made of hydrogen, helium,
and lithium, in the proportions predicted.
c)  both A and B
d)  neither A nor B
a)  Radiation has been found coming from all of space,
just as predicted.
b)  The oldest stars are made of hydrogen, helium,
and lithium, in the proportions predicted.
c)  both A and B
d)  neither A nor B
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
How do scientists test the idea that the four
fundamental forces are aspects of a more
general force that became separate ("froze
out") during the big bang?
How do scientists test the idea that the four
fundamental forces are aspects of a more
general force that became separate ("froze
out") during the big bang?
The cosmic background radiation from the big
bang has been mapped in detail. What does
it look like?
The cosmic background radiation from the big
bang has been mapped in detail. What does
it look like?
a)  It can't be tested.
b)  They study far-away objects to see how forces
behave at times early in the universe.
c)  Particle accelerators like Fermilab and the Large
Hadron Collider have tested predictions that the
weak and electromagnetic forces are related.
a)  It can't be tested.
b)  They study far-away objects to see how forces
behave at times early in the universe.
c)  Particle accelerators like Fermilab and the Large
Hadron Collider have tested predictions that the
weak and electromagnetic forces are related.
a) 
b) 
c) 
d) 
a) 
b) 
c) 
d) 
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
It is all over the sky.
It is seen even where there is no matter.
It is very uniform in overall distribution.
If you look very closely, there are slight fluctuations
from place to place.
e)  all of the above
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It is all over the sky.
It is seen even where there is no matter.
It is very uniform in overall distribution.
If you look very closely, there are slight fluctuations
from place to place.
e)  all of the above
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
True or False?: When we look at the cosmic
background radiation, we are looking farther
into space–further back in time–then when
we look at the farthest galaxies.
True or False?: When we look at the cosmic
background radiation, we are looking farther
into space–further back in time–then when
we look at the farthest galaxies.
What are the slight fluctuations seen in maps
of the cosmic background radiation?
What are the slight fluctuations seen in maps
of the cosmic background radiation?
a)  true
b)  false
a)  true
b)  false
a)  uncertainties in the map
b)  variations in the instrument's sensitivity
c)  the beginning of the formation of galaxies and
clusters of galaxies
d)  dark matter
e)  none of the above
a)  uncertainties in the map
b)  variations in the instrument's sensitivity
c)  the beginning of the formation of galaxies and
clusters of galaxies
d)  dark matter
e)  none of the above
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Grand unified theories of physics (GUTs)
predict that the very early universe (10-32
seconds after the big bang) may have had a
phase transition, releasing energy and causing
Grand unified theories of physics (GUTs)
predict that the very early universe (10-32
seconds after the big bang) may have had a
phase transition, releasing energy and causing
Can the idea of an enormous early inflation of
the universe be tested?
Can the idea of an enormous early inflation of
the universe be tested?
a)  a period of rapid expansion (inflation).
b)  tiny fluctuations predicted by quantum mechanics
to expand large enough to contribute to the
fluctuations we see in the cosmic background
radiation.
c)  a reduction in the curvature of space.
d)  all of the above
a)  a period of rapid expansion (inflation).
b)  tiny fluctuations predicted by quantum mechanics
to expand large enough to contribute to the
fluctuations we see in the cosmic background
radiation.
c)  a reduction in the curvature of space.
d)  all of the above
a)  No, it happened too long ago.
b)  Yes, inflation affects the tiny fluctuations in the
cosmic background. If we measure them
precisely, we can test inflation theories.
a)  No, it happened too long ago.
b)  Yes, inflation affects the tiny fluctuations in the
cosmic background. If we measure them
precisely, we can test inflation theories.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
True or False?: Inflation couldn't have
happened because it means that matter would
have moved faster than the speed of light, and
relativity says this is impossible.
True or False?: Inflation couldn't have
happened because it means that matter would
have moved faster than the speed of light, and
relativity says this is impossible.
Models of the universe that include inflation and
match the details of the cosmic background
radiation say the universe is about
Models of the universe that include inflation and
match the details of the cosmic background
radiation say the universe is about
a)  true
b)  false-matter isn't moving through space, space
itself is expanding
a)  true
b)  false-matter isn't moving through space, space
itself is expanding
a) 
b) 
c) 
d) 
a) 
b) 
c) 
d) 
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
4.6 billion years old.
10 billion years old.
13.7 billion years old.
Infinitely old.
© 2014 Pearson Education, Inc.
4.6 billion years old.
10 billion years old.
13.7 billion years old.
Infinitely old.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
If the expansion of the galaxies is traced
backwards in time, it indicates the universe
began about
If the expansion of the galaxies is traced
backwards in time, it indicates the universe
began about
The age of the oldest stars in our galaxy
appears to be about
The age of the oldest stars in our galaxy
appears to be about
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
a) 
b) 
c) 
d) 
e) 
6000 years ago.
4.6 billion years ago.
10 billion years old.
13–14 billion years.
none of the above
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6000 years ago.
4.6 billion years ago.
10 billion years old.
13–14 billion years.
none of the above
© 2014 Pearson Education, Inc.
6000 years old.
4.6 billion years old.
10 billion years old.
13 billion years old.
none of the above
© 2014 Pearson Education, Inc.
6000 years old.
4.6 billion years old.
10 billion years old.
13 billion years old.
none of the above
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
The best current estimate for what the universe
is made of is
The best current estimate for what the universe
is made of is
What is Olbers' paradox?
What is Olbers' paradox?
a) 
b) 
c) 
d) 
a) 
b) 
c) 
d) 
a)  If the universe was infinite, any direction you looked
you would eventually see a star.
b)  If the universe was infinitely old, the starlight would
have time to get here.
c)  The sky should look bright at night because all
areas of the sky should have a star, and time for
the starlight to reach us.
d)  all of the above
a)  If the universe was infinite, any direction you looked
you would eventually see a star.
b)  If the universe was infinitely old, the starlight would
have time to get here.
c)  The sky should look bright at night because all
areas of the sky should have a star, and time for
the starlight to reach us.
d)  all of the above
about 4% ordinary visible matter.
about 23% dark matter.
about 73% dark energy.
All of the above
© 2014 Pearson Education, Inc.
Chapter 19 - 22
about 4% ordinary visible matter.
about 23% dark matter.
about 73% dark energy.
All of the above
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Since the sky is dark at night, what's wrong
with Olbers' paradox?
Since the sky is dark at night, what's wrong
with Olbers' paradox?
Why should it not be surprising that some
galaxies contain a little more than 25% helium,
but it would be very surprising if some
galaxies contained less.
Why should it not be surprising that some
galaxies contain a little more than 25% helium,
but it would be very surprising if some
galaxies contained less.
a)  The universe is not infinite in size.
b)  There's not an infinite number of stars.
c)  The universe is not infinitely old.
a)  The universe is not infinite in size.
b)  There's not an infinite number of stars.
c)  The universe is not infinitely old.
a)  A star converts about 25% of its hydrogen into helium before it
dies, so galaxies with multiple generations of star formation can
have a higher percentage of helium.
b)  The big bang fused 25% of normal matter in the universe into
helium, and stellar nucleosynthesis can increase, but not decrease,
this amount.
c)  The helium fraction decreases with age, so younger galaxies have
more than 25%, but galaxies with less helium would be older than
the estimated age of the universe.
d)  Helium is more massive than hydrogen so it cannot readily escape
the gravitational field of a galaxy. A percentage lower than 25%
would indicate that the galaxy had no dark matter.
a)  A star converts about 25% of its hydrogen into helium before it
dies, so galaxies with multiple generations of star formation can
have a higher percentage of helium.
b)  The big bang fused 25% of normal matter in the universe into
helium, and stellar nucleosynthesis can increase, but not
decrease, this amount.
c)  The helium fraction decreases with age, so younger galaxies have
more than 25%, but galaxies with less helium would be older than
the estimated age of the universe.
d)  Helium is more massive than hydrogen so it cannot readily escape
the gravitational field of a galaxy. A percentage lower than 25%
would indicate that the galaxy had no dark matter.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
Chapter 19 - 22
True or False? Although the universe today
appears to be made mostly of matter and not
antimatter, the big bang theory suggests that
the early universe had nearly equal amounts of
matter and antimatter.
True or False? Although the universe today
appears to be made mostly of matter and not
antimatter, the big bang theory suggests that
the early universe had nearly equal amounts of
matter and antimatter.
True or False?: The theory of inflation suggests
that the structure of the universe may have
originated as tiny quantum fluctuations.
True or False?: The theory of inflation suggests
that the structure of the universe may have
originated as tiny quantum fluctuations.
a)  True, the Big Bang theory predicts that high temperatures in
the early universe generated matter-antimatter pairs, and the
amounts of each were therefore virtually equal.
b)  True, the Big Bang was started by the mutual annihilation of
virtually equal numbers of matter and antimatter particles.
c)  False, the amount of matter and antimatter in the early
universe should be exactly the same as it is today.
d)  False, the amount of matter and antimatter in the early
universe should be in the same proportion as it is today.
a)  True, the Big Bang theory predicts that high temperatures
in the early universe generated matter-antimatter pairs,
and the amounts of each were therefore virtually equal.
b)  True, the Big Bang was started by the mutual annihilation of
virtually equal numbers of matter and antimatter particles.
c)  False, the amount of matter and antimatter in the early
universe should be exactly the same as it is today.
d)  False, the amount of matter and antimatter in the early
universe should be in the same proportion as it is today.
a)  True, tiny quantum fluctuations were stretched to enormous
sizes by inflation and became large enough to grow into
galaxies and galaxy clusters.
b)  True, quantum uncertainty meant that some regions of the
universe expanded more slowly than other regions and these
slower moving regions eventually became galaxies and
galaxy clusters.
c)  False, the theory of inflation suggests that the structure of
the universe arose when radiation decoupled from matter.
d)  False, quantum fluctuations are on an atomic scale and the
structure of the universe is on the scale of galaxies.
a)  True, tiny quantum fluctuations were stretched to
enormous sizes by inflation and became large enough to
grow into galaxies and galaxy clusters.
b)  True, quantum uncertainty meant that some regions of the
universe expanded more slowly than other regions and these
slower moving regions eventually became galaxies and
galaxy clusters.
c)  False, the theory of inflation suggests that the structure of
the universe arose when radiation decoupled from matter.
d)  False, quantum fluctuations are on an atomic scale and the
structure of the universe is on the scale of galaxies.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Chapter 19 - 22
Chapter 19 - 22
True or False?: The fact that the night sky is
dark tells us that the universe cannot be infinite,
unchanging, and the same everywhere.
True or False?: The fact that the night sky is
dark tells us that the universe cannot be infinite,
unchanging, and the same everywhere.
a)  True, the dark night sky shows that the Big Bang theory must
be modified by allowing for an initial period of inflation.
b)  True, if the universe were infinite, unchanging, and the
same everywhere, the night sky would be as bright as
the surface as the Sun.
c)  False, the night sky is dark at optical wavelengths but is
blazing at microwave wavelengths.
d)  False, the night sky is dark simply because the Sun is on
the opposite side of Earth!
a)  True, the dark night sky shows that the Big Bang theory must
be modified by allowing for an initial period of inflation.
b)  True, if the universe were infinite, unchanging, and the
same everywhere, the night sky would be as bright as
the surface as the Sun.
c)  False, the night sky is dark at optical wavelengths but is
blazing at microwave wavelengths.
d)  False, the night sky is dark simply because the Sun is on
the opposite side of Earth!
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.