Question 1

Which of the following gives the two main assumptions of theoretical models of galaxy evolution?

Accepted Answer

A)  The beginning of the universe is modeled after a supernova explosion, and all elements were produced by this exploding star. 
B)  Hydrogen and helium filled all of space, and certain regions of the universe were slightly denser than others. 
C)  Hydrogen and helium filled all of space, and the entire universe had exactly the same density everywhere. 
D)  The universe has always been expanding, and denser areas contracted to form the first stars. 
E)  The universe was composed originally only of hydrogen, and all the other elements came from stars. 
A)  The beginning of the universe is modeled after a supernova explosion, and all elements were produced by this exploding star. 
B)  Hydrogen and helium filled all of space, and certain regions of the universe were slightly denser than others. 
C)  Hydrogen and helium filled all of space, and the entire universe had exactly the same density everywhere. 
D)  The universe has always been expanding, and denser areas contracted to form the first stars. 
E)  The universe was composed originally only of hydrogen, and all the other elements came from stars.

Question 2

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 3

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

Accepted Answer

A)  about 10 light-years across 
B)  about 10 parsecs 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 light-years across 
B)  about 10 parsecs 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 4

Dr. Smith believes that the Hubble constant is H₀ = 25 km/s/Mly while Dr. Jones believes it is H₀ = 19 km/s/Mly. Which statement below automatically follows?

Accepted Answer

A)  Dr. Smith believes that the universe is expanding, but Dr. Jones does not. 
B)  Dr. Smith believes that the Andromeda Galaxy (a member of our Local Group) is moving away from us at a faster speed than Dr. Jones believes. 
C)  Dr. Smith believes that the universe is older than Dr. Jones believes. 
D)  Dr. Smith believes that the universe is younger than Dr. Jones believes. 
E)  Dr. Smith believes that the universe will someday stop expanding, while Dr. Jones believes it will expand forever. 
A)  Dr. Smith believes that the universe is expanding, but Dr. Jones does not. 
B)  Dr. Smith believes that the Andromeda Galaxy (a member of our Local Group) is moving away from us at a faster speed than Dr. Jones believes. 
C)  Dr. Smith believes that the universe is older than Dr. Jones believes. 
D)  Dr. Smith believes that the universe is younger than Dr. Jones believes. 
E)  Dr. Smith believes that the universe will someday stop expanding, while Dr. Jones believes it will expand forever.

Question 5

Distant galaxies are more likely to be irregular in shape than galaxies closer to the Milky Way.

Accepted Answer

A) True 
 B)False

Question 6

Molly measures a Hubble constant of 20 km/sec/million light-years. Sam measures a Hubble constant of 25 km/sec/million light-years. All other assumptions being the same, which person would estimate a LARGER age to the universe?

Accepted Answer

A)  Molly 
B)  They both would measure the same age. 
C)  Sam 
A)  Molly 
B)  They both would measure the same age. 
C)  Sam

Question 7

Suppose we observe a source of X-rays that varies substantially in brightness over a period of a few days. What can we conclude?

Accepted Answer

A)  The X-ray source is no more than a few light-days in diameter. 
B)  The X-ray source is a quasar. 
C)  The X-ray source contains a black hole with an accretion disk. 
D)  The X-ray source must have a strong, rapidly varying magnetic field. 
A)  The X-ray source is no more than a few light-days in diameter. 
B)  The X-ray source is a quasar. 
C)  The X-ray source contains a black hole with an accretion disk. 
D)  The X-ray source must have a strong, rapidly varying magnetic field.

Question 8

Explain individual galaxies or clusters of galaxies do not expand in size despite the overall expansion of the universe implied by Hubble's Law.

Accepted Answer

The pull of gravity works to slow the ex

Question 9

All of the following observations are real. Which one does not support the theory that active galactic nuclei are powered by accretion disks around massive black holes?

Accepted Answer

A)  The most luminous active galactic nuclei have huge redshifts. 
B)  X-ray emission from active galactic nuclei can vary significantly in times as short as a few days. 
C)  The total luminosity of an active galactic nucleus can be as high as about 10 billion times that of the Sun. 
D)  Spectra of active galactic nuclei show that clouds of gas are orbiting a central object at very high speed. 
A)  The most luminous active galactic nuclei have huge redshifts. 
B)  X-ray emission from active galactic nuclei can vary significantly in times as short as a few days. 
C)  The total luminosity of an active galactic nucleus can be as high as about 10 billion times that of the Sun. 
D)  Spectra of active galactic nuclei show that clouds of gas are orbiting a central object at very high speed.

Question 10

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

Accepted Answer

Galaxies are much closer together, relat

Question 11

Which of the following is evidence for supermassive black holes in active galaxies?

Accepted Answer

A)  the discovery of powerful jets coming from a compact core 
B)  rapid changes in the luminosity of the galaxy nucleus 
C)  quasars emit approximately equal power at all wavelengths from infrared to gamma rays 
D)  the very high speeds of gas orbiting around the galactic nucleus 
E)  all of the above 
A)  the discovery of powerful jets coming from a compact core 
B)  rapid changes in the luminosity of the galaxy nucleus 
C)  quasars emit approximately equal power at all wavelengths from infrared to gamma rays 
D)  the very high speeds of gas orbiting around the galactic nucleus 
E)  all of the above

Question 12

Why are collisions between galaxies more likely than collisions between stars within a galaxy?

Accepted Answer

A)  Relative to their sizes, galaxies are closer together than stars. 
B)  Galaxies are much larger than stars. 
C)  Galaxies travel through space much faster than stars. 
D)  Galaxies have higher redshifts than stars. 
A)  Relative to their sizes, galaxies are closer together than stars. 
B)  Galaxies are much larger than stars. 
C)  Galaxies travel through space much faster than stars. 
D)  Galaxies have higher redshifts than stars.

Question 13

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

Accepted Answer

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

Question 14

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

Accepted Answer

A) True 
 B)False

Question 15

Current estimates place the age of the universe at about ________.

Accepted Answer

A)  10 billion years 
B)  10 million years 
C)  14 billion years 
D)  4 ¹/₂ billion years 
A)  10 billion years 
B)  10 million years 
C)  14 billion years 
D)  4 ¹/₂ billion years

Question 16

If we represent the Milky Way Galaxy as the size of a grapefruit, the distance to the Andromeda Galaxy would be about

Accepted Answer

A)  3 cm. 
B)  3 m. 
C)  30 m. 
D)  3 km. 
E)  300 km. 
A)  3 cm. 
B)  3 m. 
C)  30 m. 
D)  3 km. 
E)  300 km.

Question 17

Most active galactic nuclei are found at large distances from us, with relatively few nearby. What does this imply?

Accepted Answer

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

Question 18

The Redshift Controversy: The early debate on whether or not quasar redshifts were correctly interpreted by Hubble's Law (to indicate that quasars lay at enormous distances) is an excellent example of how a scientific debate was (reasonably) quickly settled by appeals to the observational evidence. Outline all of the observational evidence that quasars are indeed associated with the nuclei of distant galaxies and, therefore, their redshifts can be correctly interpreted using Hubble's Law.

Accepted Answer

The observational evidence that quasars

Question 19

What is the best way to determine a galaxy's redshift?

Accepted Answer

A)  Find the galaxy's apparent distance, and look up the redshift based on Hubble's Law. 
B)  Find the color of the galaxy, and estimate its distance based on how red the galaxy is. 
C)  Take a spectrum of the galaxy, and measure the difference in wavelength of spectral lines from the wavelengths of those same lines as measured in the laboratory. 
D)  Measure the magnitude of the galaxy, estimate its distance, and calculate its redshift using Hubble's Law. 
A)  Find the galaxy's apparent distance, and look up the redshift based on Hubble's Law. 
B)  Find the color of the galaxy, and estimate its distance based on how red the galaxy is. 
C)  Take a spectrum of the galaxy, and measure the difference in wavelength of spectral lines from the wavelengths of those same lines as measured in the laboratory. 
D)  Measure the magnitude of the galaxy, estimate its distance, and calculate its redshift using Hubble's Law.

Question 20

What two quantities did Edwin Hubble compare for a sample of galaxies to discover the expansion of the Universe?

Accepted Answer

A)  velocity and distance 
B)  luminosity and distance 
C)  velocity and temperature 
D)  luminosity and temperature 
E)  age and distance 
A)  velocity and distance 
B)  luminosity and distance 
C)  velocity and temperature 
D)  luminosity and temperature 
E)  age and distance

Which of the following gives the two main assumptions of theoretical models of galaxy evolution?

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

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

Dr. Smith believes that the Hubble constant is H₀ = 25 km/s/Mly while Dr. Jones believes it is H₀ = 19 km/s/Mly. Which statement below automatically follows?

Distant galaxies are more likely to be irregular in shape than galaxies closer to the Milky Way.

Molly measures a Hubble constant of 20 km/sec/million light-years. Sam measures a Hubble constant of 25 km/sec/million light-years. All other assumptions being the same, which person would estimate a LARGER age to the universe?

Suppose we observe a source of X-rays that varies substantially in brightness over a period of a few days. What can we conclude?

Explain individual galaxies or clusters of galaxies do not expand in size despite the overall expansion of the universe implied by Hubble's Law.

All of the following observations are real. Which one does not support the theory that active galactic nuclei are powered by accretion disks around massive black holes?

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

Which of the following is evidence for supermassive black holes in active galaxies?

Why are collisions between galaxies more likely than collisions between stars within a galaxy?

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

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

Current estimates place the age of the universe at about ________.

If we represent the Milky Way Galaxy as the size of a grapefruit, the distance to the Andromeda Galaxy would be about

Most active galactic nuclei are found at large distances from us, with relatively few nearby. What does this imply?

What is the best way to determine a galaxy's redshift?

What two quantities did Edwin Hubble compare for a sample of galaxies to discover the expansion of the Universe?

Our Place in 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 Planetary Systems: Our Solar System and Beyond

Earth and the Terrestrial Worlds

Jovian Planet Systems

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

Our Star

Surveying the Stars

Star Stuff

Bizarre Stellar Graveyard

Our Galaxy

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

The Beginning of Time

Life in the Universe

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Exam 15: Galaxies and the Foundation of Modern Cosmology

Which of the following gives the two main assumptions of theoretical models of galaxy evolution?

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

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

Dr. Smith believes that the Hubble constant is H₀ = 25 km/s/Mly while Dr. Jones believes it is H₀ = 19 km/s/Mly. Which statement below automatically follows?

Distant galaxies are more likely to be irregular in shape than galaxies closer to the Milky Way.

Molly measures a Hubble constant of 20 km/sec/million light-years. Sam measures a Hubble constant of 25 km/sec/million light-years. All other assumptions being the same, which person would estimate a LARGER age to the universe?

Suppose we observe a source of X-rays that varies substantially in brightness over a period of a few days. What can we conclude?

Explain individual galaxies or clusters of galaxies do not expand in size despite the overall expansion of the universe implied by Hubble's Law.

All of the following observations are real. Which one does not support the theory that active galactic nuclei are powered by accretion disks around massive black holes?

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

Which of the following is evidence for supermassive black holes in active galaxies?

Why are collisions between galaxies more likely than collisions between stars within a galaxy?

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

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

Current estimates place the age of the universe at about ________.

If we represent the Milky Way Galaxy as the size of a grapefruit, the distance to the Andromeda Galaxy would be about

Most active galactic nuclei are found at large distances from us, with relatively few nearby. What does this imply?

What is the best way to determine a galaxy's redshift?

What two quantities did Edwin Hubble compare for a sample of galaxies to discover the expansion of the Universe?

Our Place in 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 Planetary Systems: Our Solar System and Beyond

Earth and the Terrestrial Worlds

Jovian Planet Systems

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

Our Star

Surveying the Stars

Star Stuff

Bizarre Stellar Graveyard

Our Galaxy

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

The Beginning of Time

Life in the Universe

Filters