Question 1

What can be inferred about the distance traveled by the blob of plasma shown moving in this figure at almost the speed of light?

Accepted Answer

A) It moved several light years between 1991 and 1997. 
B) It could only have moved a small fraction of a light year between 1991 and 1997. 
C) There is not enough information to tell anything about the distance traveled by the plasma. 
A) It moved several light years between 1991 and 1997. 
B) It could only have moved a small fraction of a light year between 1991 and 1997. 
C) There is not enough information to tell anything about the distance traveled by the plasma.

Question 2

Use the graph above showing data for the brightest galaxies in clusters of galaxies to answer the following question. You find a cluster of galaxies, but you do not know how far away it is. The brightest galaxy's infrared color is 0.65. Given the data for brightest galaxies in the graph above, your best estimate for the distance is

Accepted Answer

A) 2)5 × 109 (2.5 billion)light years. 
B) 1 × 109 (1 billion)light years. 
C) 4 × 109 (4 billion)light years. 
D) It is impossible to say since there are exceptions. 
A) 2)5 × 109 (2.5 billion)light years. 
B) 1 × 109 (1 billion)light years. 
C) 4 × 109 (4 billion)light years. 
D) It is impossible to say since there are exceptions.

Question 3

Why is a dense cloud more likely to produce an elliptical galaxy than a spiral galaxy?

Accepted Answer

A) The more frequent collisions between particles randomize the particle orbits. 
B) The higher density of gas has a stronger force of gravity, and therefore the cloud collapses more quickly. 
C) The higher gas density forms stars more efficiently, so all the gas is converted into stars before a disk can form. 
D) The force of gravity can pull the material into a more spherical shape. 
E) The thickness of the dense cloud prevents a disk from forming. 
A) The more frequent collisions between particles randomize the particle orbits. 
B) The higher density of gas has a stronger force of gravity, and therefore the cloud collapses more quickly. 
C) The higher gas density forms stars more efficiently, so all the gas is converted into stars before a disk can form. 
D) The force of gravity can pull the material into a more spherical shape. 
E) The thickness of the dense cloud prevents a disk from forming.

Question 4

Most active galactic nuclei are at large distances from us; relatively few nearby galaxies harbor active galactic nuclei. What does this imply?

Accepted Answer

A) Active galactic nuclei can form only at large distances from the Milky Way. 
B) Massive black holes existed only when the universe was young and no longer exist today. 
C) Active galactic nuclei tend to become less active as they age. 
D) The jets seen in many active galactic nuclei must cause them to move far away from us. 
A) Active galactic nuclei can form only at large distances from the Milky Way. 
B) Massive black holes existed only when the universe was young and no longer exist today. 
C) Active galactic nuclei tend to become less active as they age. 
D) The jets seen in many active galactic nuclei must cause them to move far away from us.

Question 5

What is Hubble's law?

Accepted Answer

A) The luminosity of the Cepheid variable star is directly proportional to its pulsation period. 
B) The recession velocity of a galaxy is inversely proportional to its distance. 
C) The faster a spiral galaxy's rotation speed, the less luminous it is. 
D) The recession velocity of a galaxy is directly proportional to its distance. 
E) The faster a spiral galaxy's rotation speed, the more luminous it is. 
A) The luminosity of the Cepheid variable star is directly proportional to its pulsation period. 
B) The recession velocity of a galaxy is inversely proportional to its distance. 
C) The faster a spiral galaxy's rotation speed, the less luminous it is. 
D) The recession velocity of a galaxy is directly proportional to its distance. 
E) The faster a spiral galaxy's rotation speed, the more luminous it is.

Question 6

All spiral galaxies have both a disk and spheroidal component to their stellar populations.

Accepted Answer

A) True 
 B)False

Question 7

How many more stars does a starburst galaxy form, in one year, than the Milky Way?

Accepted Answer

A) about ten 
B) about a thousand 
C) about a hundred 
D) a few 
E) about the same, but it does so for much longer 
A) about ten 
B) about a thousand 
C) about a hundred 
D) a few 
E) about the same, but it does so for much longer

Question 8

Suppose that Hubble's constant were 20 kilometers per second per million light- years. How fast would we expect a galaxy 100 million light- years away to be moving? (Assume the motion is due only to Hubble's law.)

Accepted Answer

A) away from us at 2,000 km/s 
B) away from us at 20,000 km/s 
C) away from us at 200 km/s 
D) toward us at 2,000 km/s 
A) away from us at 2,000 km/s 
B) away from us at 20,000 km/s 
C) away from us at 200 km/s 
D) toward us at 2,000 km/s

Question 9

How are the jets produced by radio galaxies similar to those produced by protostars?

Accepted Answer

Jets in radio galaxies and in protostars

Question 10

I observe a galaxy that is 100 million light years away. Which of the following do I see?

Accepted Answer

A) the light from the galaxy as it is today, and it is redshifted 
B) the light from the galaxy as it was 100 million years ago, and it is redshifted 
C) the light from the galaxy as it is today, and it is blueshifted 
D) the light from the galaxy as it was 100 million years ago, and it is blueshifted 
E) Nothing: the galaxy lies beyond the cosmological horizon. 
A) the light from the galaxy as it is today, and it is redshifted 
B) the light from the galaxy as it was 100 million years ago, and it is redshifted 
C) the light from the galaxy as it is today, and it is blueshifted 
D) the light from the galaxy as it was 100 million years ago, and it is blueshifted 
E) Nothing: the galaxy lies beyond the cosmological horizon.

Question 11

Which of the following is not a good reason why white- dwarf supernovae are good standard candles for distance measurements?

Accepted Answer

A) White- dwarf supernovae are so bright that they can be detected even in very distant galaxies. 
B) White- dwarf supernovae occur only among young and extremely bright stars. 
C) White- dwarf supernovae are common enough that we detect several every year. 
D) All white- dwarf supernovae have similar light curves, which makes them easy to distinguish from massive- star supernovae. 
E) All white- dwarf supernovae involve the explosion of stars of nearly the same mass. 
A) White- dwarf supernovae are so bright that they can be detected even in very distant galaxies. 
B) White- dwarf supernovae occur only among young and extremely bright stars. 
C) White- dwarf supernovae are common enough that we detect several every year. 
D) All white- dwarf supernovae have similar light curves, which makes them easy to distinguish from massive- star supernovae. 
E) All white- dwarf supernovae involve the explosion of stars of nearly the same mass.

Question 12

Massive- star supernovae and white- dwarf supernovae work equally well as standard candles for measuring cosmic distances.

Accepted Answer

A) True 
 B)False

Question 13

Although the entire universe may be much larger than our observable universe, we can see only within our observable universe. The "boundary" of our observable universe is called .

Accepted Answer

A) the lookback time 
B) the cosmological horizon 
C) the Big Bang 
D) the Hubble Deep Field 
A) the lookback time 
B) the cosmological horizon 
C) the Big Bang 
D) the Hubble Deep Field

Question 14

What is the most accurate way to determine the distance to a nearby star?

Accepted Answer

A) Cepheid variables 
B) Hubble's law 
C) stellar parallax 
D) radar ranging 
E) main- sequence fitting 
A) Cepheid variables 
B) Hubble's law 
C) stellar parallax 
D) radar ranging 
E) main- sequence fitting

Question 15

How do quasars produce so much energy in such a small volume?

Accepted Answer

As matter falls toward the central black

Question 16

Explain why galaxy- galaxy interactions are far more common than star- star interactions.

Accepted Answer

Galaxies are much closer together, relat

Question 17

What does cosmological redshift do to light?

Accepted Answer

A) makes it brighter 
B) makes it slow down 
C) makes all light infrared 
D) stretches its wavelength 
A) makes it brighter 
B) makes it slow down 
C) makes all light infrared 
D) stretches its wavelength

Question 18

Dr. X believes that the Hubble constant is H0 = 20 km/s/Mly while Dr. Y believes it is H0 = 24 km/s/Mly. Which statement below automatically follows?

Accepted Answer

A) Dr. X believes that the universe is older than Dr. Y believes. 
B) Dr. X believes that the Andromeda Galaxy (a member of our Local Group)is moving away from us at a slower speed than Dr. Y believes. 
C) Dr. X believes that the universe has a much higher density than Dr. Y believes. 
D) Dr. X believes that the universe is expanding, but Dr. Y does not. 
E) Dr. X believes that the universe will someday stop expanding, while Dr. Y believes it will expand forever. 
A) Dr. X believes that the universe is older than Dr. Y believes. 
B) Dr. X believes that the Andromeda Galaxy (a member of our Local Group)is moving away from us at a slower speed than Dr. Y believes. 
C) Dr. X believes that the universe has a much higher density than Dr. Y believes. 
D) Dr. X believes that the universe is expanding, but Dr. Y does not. 
E) Dr. X believes that the universe will someday stop expanding, while Dr. Y believes it will expand forever.

Question 19

Summarize the links in the distance chain that allow us to estimate distances to the farthest reaches of the universe.

Accepted Answer

We can determine the distances in the so

Question 20

Which of the following types of galaxies have a disk and spheroidal component but lack spiral arms?

Accepted Answer

A) lenticulars 
B) ellipticals 
C) irregulars 
D) all of the above 
A) lenticulars 
B) ellipticals 
C) irregulars 
D) all of the above

What can be inferred about the distance traveled by the blob of plasma shown moving in this figure at almost the speed of light?

Why is a dense cloud more likely to produce an elliptical galaxy than a spiral galaxy?

Most active galactic nuclei are at large distances from us; relatively few nearby galaxies harbor active galactic nuclei. What does this imply?

What is Hubble's law?

All spiral galaxies have both a disk and spheroidal component to their stellar populations.

How many more stars does a starburst galaxy form, in one year, than the Milky Way?

Suppose that Hubble's constant were 20 kilometers per second per million light- years. How fast would we expect a galaxy 100 million light- years away to be moving? (Assume the motion is due only to Hubble's law.)

How are the jets produced by radio galaxies similar to those produced by protostars?

I observe a galaxy that is 100 million light years away. Which of the following do I see?

Which of the following is not a good reason why white- dwarf supernovae are good standard candles for distance measurements?

Massive- star supernovae and white- dwarf supernovae work equally well as standard candles for measuring cosmic distances.

Although the entire universe may be much larger than our observable universe, we can see only within our observable universe. The "boundary" of our observable universe is called .

What is the most accurate way to determine the distance to a nearby star?

How do quasars produce so much energy in such a small volume?

Explain why galaxy- galaxy interactions are far more common than star- star interactions.

What does cosmological redshift do to light?

Dr. X believes that the Hubble constant is H0 = 20 km/s/Mly while Dr. Y believes it is H0 = 24 km/s/Mly. Which statement below automatically follows?

Summarize the links in the distance chain that allow us to estimate distances to the farthest reaches of the universe.

Which of the following types of galaxies have a disk and spheroidal component but lack spiral arms?

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: the New Science of Distant Worlds

Our Star

Surveying the Stars

Star Stuff

The Bizarre Stellar Graveyard

Our Galaxy

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

Filters

Exam 16: A Universe of Galaxies

What can be inferred about the distance traveled by the blob of plasma shown moving in this figure at almost the speed of light?

Why is a dense cloud more likely to produce an elliptical galaxy than a spiral galaxy?

Most active galactic nuclei are at large distances from us; relatively few nearby galaxies harbor active galactic nuclei. What does this imply?

What is Hubble's law?

All spiral galaxies have both a disk and spheroidal component to their stellar populations.

How many more stars does a starburst galaxy form, in one year, than the Milky Way?

Suppose that Hubble's constant were 20 kilometers per second per million light- years. How fast would we expect a galaxy 100 million light- years away to be moving? (Assume the motion is due only to Hubble's law.)

How are the jets produced by radio galaxies similar to those produced by protostars?

I observe a galaxy that is 100 million light years away. Which of the following do I see?

Which of the following is not a good reason why white- dwarf supernovae are good standard candles for distance measurements?

Massive- star supernovae and white- dwarf supernovae work equally well as standard candles for measuring cosmic distances.

Although the entire universe may be much larger than our observable universe, we can see only within our observable universe. The "boundary" of our observable universe is called .

What is the most accurate way to determine the distance to a nearby star?

How do quasars produce so much energy in such a small volume?

Explain why galaxy- galaxy interactions are far more common than star- star interactions.

What does cosmological redshift do to light?

Dr. X believes that the Hubble constant is H0 = 20 km/s/Mly while Dr. Y believes it is H0 = 24 km/s/Mly. Which statement below automatically follows?

Summarize the links in the distance chain that allow us to estimate distances to the farthest reaches of the universe.

Which of the following types of galaxies have a disk and spheroidal component but lack spiral arms?

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: the New Science of Distant Worlds

Our Star

Surveying the Stars

Star Stuff

The Bizarre Stellar Graveyard

Our Galaxy

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

Filters