Question 1

Describe two ways in which you could measure the mass of a galaxy cluster.

Accepted Answer

Here are three possible answers:
(1)Determine the mass needed to bind the hot X-ray-emitting gas to the cluster.
(2)Determine the velocities of galaxies in the cluster and use their kinetic energy to estimate the total mass of the cluster.
(3)Determine the mass using the gravitational lensing of background galaxies.

Question 2

If neutrinos have mass but do not interact much with normal matter,why can't they be the dominant form of dark matter in the universe?

Accepted Answer

A)  Structure formation would have started with large objects fragmenting into smaller objects. 
B)  Structure formation would have started with small objects merging to form larger objects. 
C)  Neutrinos would decay over time and disappear,causing galaxies to fall apart. 
D)  Neutrinos would not gravitationally lens background galaxies. 
A)  Structure formation would have started with large objects fragmenting into smaller objects. 
B)  Structure formation would have started with small objects merging to form larger objects. 
C)  Neutrinos would decay over time and disappear,causing galaxies to fall apart. 
D)  Neutrinos would not gravitationally lens background galaxies. A

Question 3

We currently live in the universe during its

Accepted Answer

A)  era of stars. 
B)  era of degeneracy. 
C)  era of black holes. 
D)  era of darkness. 
A)  era of stars. 
B)  era of degeneracy. 
C)  era of black holes. 
D)  era of darkness. A

Question 4

Put the following eras in the history of the evolution of the universe in their proper order from the earliest to the latest: black hole era,dark era,degenerate era,primordial era,stelliferous era.

Accepted Answer

From first to last a

Question 5

Astronomers have determined that the Milky Way is being pulled toward a massive structure called the "Great Attractor" but are unable to observe it because it is too far away.

Accepted Answer

A) True 
 B)False

Question 6

If a galaxy is a member of a large cluster of galaxies,like the Coma cluster,the galaxy would have a typical velocity of 1,000 km/s.If the cluster is 10 Mpc in diameter,how long would it take the galaxy to cross from one side of the cluster to another?

Accepted Answer

A)  10,000 years 
B)  10 million years 
C)  100 million years 
D)  10 billion years 
A)  10,000 years 
B)  10 million years 
C)  100 million years 
D)  10 billion years

Question 7

Is the theory behind Type IV multiverses testable?

Accepted Answer

A)  Yes,because if you wait long enough you can see past your current horizon. 
B)  Yes,because your universe is a part of a larger structure. 
C)  No,because the different multiverses cannot communicate with one another. 
D)  No,because quantum mechanics forbids it. 
A)  Yes,because if you wait long enough you can see past your current horizon. 
B)  Yes,because your universe is a part of a larger structure. 
C)  No,because the different multiverses cannot communicate with one another. 
D)  No,because quantum mechanics forbids it.

Question 8

How do we know how fast the Milky Way is moving relative to the local universe? What are we moving toward,and why do we not know much about it?

Accepted Answer

The Doppler shift of the CBR tells us ho

Question 9

If the quantum fluctuations imprinted on the dark matter halos at the time of the formation of the CBR were ten times larger,galaxies would likely be

Accepted Answer

A)  smaller. 
B)  larger. 
C)  more numerous. 
D)  nonexistent. 
A)  smaller. 
B)  larger. 
C)  more numerous. 
D)  nonexistent.

Question 10

If dark energy were to instantly cease,our universe would continue to expand forever.

Accepted Answer

A) True 
 B)False

Question 11

In order from first to last,the specific eras in the universe's history are known as the

Accepted Answer

A)  Primordial,stelliferous,degenerate,and dark eras. 
B)  Stelliferous,black hole,and entropy eras. 
C)  Primordial,stelliferous,black hole,and entropy eras. 
D)  Primordial,stelliferous,degenerate,black hole,and dark eras. 
A)  Primordial,stelliferous,degenerate,and dark eras. 
B)  Stelliferous,black hole,and entropy eras. 
C)  Primordial,stelliferous,black hole,and entropy eras. 
D)  Primordial,stelliferous,degenerate,black hole,and dark eras.

Question 12

Explain why a galaxy can collapse to a much smaller size than its dark matter halo.

Accepted Answer

Dark matter collapses down until it is s

Question 13

Why can't dark matter halos collapse to be the same size as the visible parts of galaxies?

Accepted Answer

A)  Dark matter can't dissipate its energy through collisions. 
B)  Dark matter is mostly made of mini-black holes. 
C)  Dark matter has much more angular momentum. 
D)  Dark matter annihilates when it begins to get that dense. 
A)  Dark matter can't dissipate its energy through collisions. 
B)  Dark matter is mostly made of mini-black holes. 
C)  Dark matter has much more angular momentum. 
D)  Dark matter annihilates when it begins to get that dense.

Question 14

What does the large-scale structure of the universe look most like?

Accepted Answer

A)  A sponge with many large holes 
B)  A loaf of wheat bread with many tiny holes 
C)  A plate of flat noodles 
D)  A jar of marbles 
A)  A sponge with many large holes 
B)  A loaf of wheat bread with many tiny holes 
C)  A plate of flat noodles 
D)  A jar of marbles

Question 15

What is the main reason that astrophysicists cannot calculate the evolution of galaxies exactly?

Accepted Answer

Star formation is not well und

Question 16

Why do astronomers think that cold dark matter (as opposed to hot dark matter)is the primary component of dark matter in galaxies?

Accepted Answer

Because cold dark ma

Question 17

We expect the galaxies that we see at a redshift of 4 will be __________ than galaxies today.

Accepted Answer

A)  more irregular and redder 
B)  larger and redder 
C)  smaller and bluer 
D)  smaller and redder 
A)  more irregular and redder 
B)  larger and redder 
C)  smaller and bluer 
D)  smaller and redder

Question 18

Which of the following is NOT a way in which astronomers detect dark matter in clusters of galaxies?

Accepted Answer

A)  By determining the amount of mass necessary to gravitationally collapse clouds of gas to form the number of stars present 
B)  By determining the amount of mass necessary to gravitationally hold onto the hot gas surrounding galaxy clusters 
C)  By determining the amount of mass necessary to gravitationally hold a cluster of galaxies together 
D)  By determining the amount of mass necessary to gravitationally lens images of distant objects 
A)  By determining the amount of mass necessary to gravitationally collapse clouds of gas to form the number of stars present 
B)  By determining the amount of mass necessary to gravitationally hold onto the hot gas surrounding galaxy clusters 
C)  By determining the amount of mass necessary to gravitationally hold a cluster of galaxies together 
D)  By determining the amount of mass necessary to gravitationally lens images of distant objects

Question 19

There are fluctuations in the CBR due to the fact that clumps of dark matter had already begun to form in the universe.

Accepted Answer

A) True 
 B)False

Question 20

We currently find ourselves in the stelliferous era in the history of our universe.

Accepted Answer

A) True 
 B)False

Exam 22: The Origin of Structure

Describe two ways in which you could measure the mass of a galaxy cluster.

If neutrinos have mass but do not interact much with normal matter,why can't they be the dominant form of dark matter in the universe?

We currently live in the universe during its

Put the following eras in the history of the evolution of the universe in their proper order from the earliest to the latest: black hole era,dark era,degenerate era,primordial era,stelliferous era.

Astronomers have determined that the Milky Way is being pulled toward a massive structure called the "Great Attractor" but are unable to observe it because it is too far away.

If a galaxy is a member of a large cluster of galaxies,like the Coma cluster,the galaxy would have a typical velocity of 1,000 km/s.If the cluster is 10 Mpc in diameter,how long would it take the galaxy to cross from one side of the cluster to another?

Is the theory behind Type IV multiverses testable?

How do we know how fast the Milky Way is moving relative to the local universe? What are we moving toward,and why do we not know much about it?

If the quantum fluctuations imprinted on the dark matter halos at the time of the formation of the CBR were ten times larger,galaxies would likely be

If dark energy were to instantly cease,our universe would continue to expand forever.

In order from first to last,the specific eras in the universe's history are known as the

Explain why a galaxy can collapse to a much smaller size than its dark matter halo.

Why can't dark matter halos collapse to be the same size as the visible parts of galaxies?

What does the large-scale structure of the universe look most like?

What is the main reason that astrophysicists cannot calculate the evolution of galaxies exactly?

Why do astronomers think that cold dark matter (as opposed to hot dark matter)is the primary component of dark matter in galaxies?

We expect the galaxies that we see at a redshift of 4 will be __________ than galaxies today.

Which of the following is NOT a way in which astronomers detect dark matter in clusters of galaxies?

There are fluctuations in the CBR due to the fact that clumps of dark matter had already begun to form in the universe.

We currently find ourselves in the stelliferous era in the history of our universe.

Why Learn Astronomy

Patterns in the Skymotions of Earth

Gravity and Orbitsa Celestial Ballet

Light

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Gravity Is More Than Keplers Laws

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

A Run-Of-The-Mill G-Type Starour Sun

Star Formation and the Interstellar Medium

Stars in the Slow Lanelow-Mass Stellar Evolution

Live Fast,die Younghigh-Mass Stellar Evolution

Our Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Life

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