Question 1

According to the theory that active galactic nuclei are powered by supermassive black holes, the high luminosity of an active galactic nucleus primarily consists of .

Accepted Answer

A) light emitted by hot gas in an accretion disk that swirls around the black hole 
B) radio waves emitted from radio lobes found on either side of the galaxy we see in visible light 
C) the combined light of thousands of young, high- mass stars that orbit the black hole 
D) intense radiation emitted by the black hole itself 
A) light emitted by hot gas in an accretion disk that swirls around the black hole 
B) radio waves emitted from radio lobes found on either side of the galaxy we see in visible light 
C) the combined light of thousands of young, high- mass stars that orbit the black hole 
D) intense radiation emitted by the black hole itself

Question 2

Does It Matter What the Universe Expands Into? A natural question of anyone who meets Hubble's Law for the first time is to ask what exactly the universe is expanding into. This is often further motivated by the analogy of an inflating balloon universe, where two- dimensional galaxies ride along on the surface of the balloon. Imagine that you live in one of these balloon- borne galaxies. Your universe is the surface of the balloon. You can move along the surface, but you can never exist above or below it. Now one of your two- dimensional friends asks what your (balloon)space is expanding into. Do you need to answer this question, or can the expansion you experience be completely described without reference to an unseen, third- dimension? Imagine someone argues that question "what is the universe expanding into?" does not even need an answer! Would you agree or disagree? Explain. If you disagree, would there be any way to gather scientific evidence to answer this question?

Accepted Answer

The question of what the universe is exp

Question 3

Why should galaxy collisions have been more common in the past than they are today?

Accepted Answer

A) Galaxies attracted each other more strongly in the past because they were more massive; they had not yet turned most of their mass into stars and light. 
B) Galaxies were much bigger in the past because they had not contracted completely. 
C) Galaxies were closer together in the past because the universe was smaller. 
D) Galaxy collisions shouldn't have been more common in the past than they are now. 
E) Galaxies were more active in the past and therefore would have collided with each other more frequently. 
A) Galaxies attracted each other more strongly in the past because they were more massive; they had not yet turned most of their mass into stars and light. 
B) Galaxies were much bigger in the past because they had not contracted completely. 
C) Galaxies were closer together in the past because the universe was smaller. 
D) Galaxy collisions shouldn't have been more common in the past than they are now. 
E) Galaxies were more active in the past and therefore would have collided with each other more frequently.

Question 4

A protogalactic cloud with very little angular momentum is more likely to form an elliptical galaxy than a spiral galaxy.

Accepted Answer

A) True 
 B)False

Question 5

If an object doubles its luminosity in 10 hours, how large can the emitting source of light be?

Accepted Answer

A) about 10 parsecs across 
B) about 10 light- years across 
C) about 10 light- hours across 
D) varies depending on how luminous the object is 
E) varies depending on how far away the object is 
A) about 10 parsecs across 
B) about 10 light- years across 
C) about 10 light- hours across 
D) varies depending on how luminous the object is 
E) varies depending on how far away the object is

Question 6

Hubble's galaxy classification diagram (the "tuning fork").

Accepted Answer

A) relates galaxies according to their shapes, but not according to any evolutionary status 
B) explains active galactic nuclei 
C) suggests the existence of black holes 
D) shows how galaxies evolve from one form to another 
A) relates galaxies according to their shapes, but not according to any evolutionary status 
B) explains active galactic nuclei 
C) suggests the existence of black holes 
D) shows how galaxies evolve from one form to another

Question 7

How does a lenticular galaxy differ from a normal spiral galaxy?

Accepted Answer

A) It has no gas or dust. 
B) It is flatter in shape. 
C) It has an elongated bulge resembling a bar more than a sphere. 
D) It has no bulge. 
E) It has no spiral arms. 
A) It has no gas or dust. 
B) It is flatter in shape. 
C) It has an elongated bulge resembling a bar more than a sphere. 
D) It has no bulge. 
E) It has no spiral arms.

Question 8

In the 1960s, Maarten Schmidt determined that quasars were very distant objects by

Accepted Answer

A) determining how small the source of light was from its luminosity variations. 
B) determining how luminous they were. 
C) determining their parallax angles. 
D) determining their redshifts. 
E) discovering that they were embedded in distant galaxies. 
A) determining how small the source of light was from its luminosity variations. 
B) determining how luminous they were. 
C) determining their parallax angles. 
D) determining their redshifts. 
E) discovering that they were embedded in distant galaxies.

Question 9

Galaxy mergers take hundreds of millions of years to complete.

Accepted Answer

A) True 
 B)False

Question 10

Why are Cepheid variables important?

Accepted Answer

A) Cepheids variables are pulsating stars whose pulsation periods are directly related to their true luminosities. Therefore they can be used as distance indicators. 
B) Cepheids variables are supermassive stars that are on the verge of becoming supernovae. Therefore they allow us to choose candidates to watch if we hope to observe a supernova. 
C) Cepheids variables are a type of irregular galaxy, much more common in the early universe. Therefore they help to understand how galaxies formed. 
D) Cepheid variables are stars that vary in brightness because they harbor a black hole. Therefore, they provide direct evidence for black holes. 
A) Cepheids variables are pulsating stars whose pulsation periods are directly related to their true luminosities. Therefore they can be used as distance indicators. 
B) Cepheids variables are supermassive stars that are on the verge of becoming supernovae. Therefore they allow us to choose candidates to watch if we hope to observe a supernova. 
C) Cepheids variables are a type of irregular galaxy, much more common in the early universe. Therefore they help to understand how galaxies formed. 
D) Cepheid variables are stars that vary in brightness because they harbor a black hole. Therefore, they provide direct evidence for black holes.

Question 11

The unusually bright centers found in some galaxies are called .

Accepted Answer

A) halos 
B) supermassive black holes 
C) active galactic nuclei 
D) starbursts 
A) halos 
B) supermassive black holes 
C) active galactic nuclei 
D) starbursts

Question 12

Which of the following is true about irregular galaxies?

Accepted Answer

A) They have significant spheroidal component. 
B) They are composed solely of old stars. 
C) They have well defined spiral arms. 
D) They have reddish colors. 
E) They were more common when the universe was younger. 
A) They have significant spheroidal component. 
B) They are composed solely of old stars. 
C) They have well defined spiral arms. 
D) They have reddish colors. 
E) They were more common when the universe was younger.

Question 13

Does Hubble's law work well for galaxies in the Local Group? Why or why not?

Accepted Answer

A) No, because Hubble did not know the Local Group existed when he discovered his law. 
B) No, because we do not know the precise value of Hubble's constant. 
C) No, because galaxies in the Local Group are gravitationally bound together. 
D) Yes, it works so well that we have never detected any measurable deviations from its predictions. 
A) No, because Hubble did not know the Local Group existed when he discovered his law. 
B) No, because we do not know the precise value of Hubble's constant. 
C) No, because galaxies in the Local Group are gravitationally bound together. 
D) Yes, it works so well that we have never detected any measurable deviations from its predictions.

Question 14

Building new telescopes: With current telescopes, we can see galaxies as they existed 1 billion years after the Big Bang. Discuss innovations that could be made with new telescopes in order to see even further.

Accepted Answer

Answer should primarily focus

Question 15

What is the current limit to distances we can measure via parallax, until the results of the new Gaia mission become available?

Accepted Answer

A) about 100 light years 
B) about 1000 light years 
C) about 100,000 light years 
D) about 10,000 light years 
A) about 100 light years 
B) about 1000 light years 
C) about 100,000 light years 
D) about 10,000 light years

Question 16

There are more large spiral galaxies than there are large elliptical galaxies.

Accepted Answer

A) True 
 B)False

Question 17

Recall that a raisin cake is sometimes used to imagine how an expanding universe behaves. Suppose you are in a uniformly expanding raisin cake, sitting on Raisin A, looking at Raisin B, 2 cm away from you. Raisin B is moving away from you at 1 cm/sec. At the same time, you observe another Raisin C, which is moving away from you at 3 cm/sec. How far away is Raisin C from Raisin A?

Accepted Answer

A) 2/3 cm 
B) 3/2 cm 
C) 6 cm 
D) 3 cm 
E) impossible to say 
A) 2/3 cm 
B) 3/2 cm 
C) 6 cm 
D) 3 cm 
E) impossible to say

Question 18

Stars continue to form in the halo of our Galaxy today.

Accepted Answer

A) True 
 B)False

Question 19

In this picture, we are seeing light from the circled elliptical galaxy (HUDF- JD2)from when the universe was only about 800 million years old. The spiral galaxy below it is much closer. Why does HUDF- JD2 appear a deep red, compared to the whitish color of the nearby spiral?

Accepted Answer

A) Thick dust from active star formation blocks all the blue light, only letting red light escape. 
B) At such a large distance, all the light emitted by it is very redshifted. 
C) Even at this young age, the galaxy contains few high mass blue stars. 
D) A and B 
E) B and C 
A) Thick dust from active star formation blocks all the blue light, only letting red light escape. 
B) At such a large distance, all the light emitted by it is very redshifted. 
C) Even at this young age, the galaxy contains few high mass blue stars. 
D) A and B 
E) B and C

Question 20

Hubble's "constant" is constant in

Accepted Answer

A) space. 
B) time. 
C) space and time. 
D) our Galaxy, but it is different in others. 
A) space. 
B) time. 
C) space and time. 
D) our Galaxy, but it is different in others.

According to the theory that active galactic nuclei are powered by supermassive black holes, the high luminosity of an active galactic nucleus primarily consists of .

Why should galaxy collisions have been more common in the past than they are today?

A protogalactic cloud with very little angular momentum is more likely to form an elliptical galaxy than a spiral galaxy.

If an object doubles its luminosity in 10 hours, how large can the emitting source of light be?

Hubble's galaxy classification diagram (the "tuning fork").

How does a lenticular galaxy differ from a normal spiral galaxy?

In the 1960s, Maarten Schmidt determined that quasars were very distant objects by

Galaxy mergers take hundreds of millions of years to complete.

Why are Cepheid variables important?

The unusually bright centers found in some galaxies are called .

Which of the following is true about irregular galaxies?

Does Hubble's law work well for galaxies in the Local Group? Why or why not?

Building new telescopes: With current telescopes, we can see galaxies as they existed 1 billion years after the Big Bang. Discuss innovations that could be made with new telescopes in order to see even further.

What is the current limit to distances we can measure via parallax, until the results of the new Gaia mission become available?

There are more large spiral galaxies than there are large elliptical galaxies.

Stars continue to form in the halo of our Galaxy today.

In this picture, we are seeing light from the circled elliptical galaxy (HUDF- JD2)from when the universe was only about 800 million years old. The spiral galaxy below it is much closer. Why does HUDF- JD2 appear a deep red, compared to the whitish color of the nearby spiral?

Hubble's "constant" is constant in

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

According to the theory that active galactic nuclei are powered by supermassive black holes, the high luminosity of an active galactic nucleus primarily consists of .

Why should galaxy collisions have been more common in the past than they are today?

A protogalactic cloud with very little angular momentum is more likely to form an elliptical galaxy than a spiral galaxy.

If an object doubles its luminosity in 10 hours, how large can the emitting source of light be?

Hubble's galaxy classification diagram (the "tuning fork").

How does a lenticular galaxy differ from a normal spiral galaxy?

In the 1960s, Maarten Schmidt determined that quasars were very distant objects by

Galaxy mergers take hundreds of millions of years to complete.

Why are Cepheid variables important?

The unusually bright centers found in some galaxies are called .

Which of the following is true about irregular galaxies?

Does Hubble's law work well for galaxies in the Local Group? Why or why not?

Building new telescopes: With current telescopes, we can see galaxies as they existed 1 billion years after the Big Bang. Discuss innovations that could be made with new telescopes in order to see even further.

What is the current limit to distances we can measure via parallax, until the results of the new Gaia mission become available?

There are more large spiral galaxies than there are large elliptical galaxies.

Stars continue to form in the halo of our Galaxy today.

In this picture, we are seeing light from the circled elliptical galaxy (HUDF- JD2)from when the universe was only about 800 million years old. The spiral galaxy below it is much closer. Why does HUDF- JD2 appear a deep red, compared to the whitish color of the nearby spiral?

Hubble's "constant" is constant in

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