Question 1

In the figure shown below, the upper spectrum is from hydrogen at rest in a laboratory, and the lower spectrum is from a galaxy. How far away is this galaxy?

Accepted Answer

A)  110 Mpc 
B)  170 Mpc 
C)  230 Mpc 
D)  280 Mpc 
E)  340 Mpc 
A)  110 Mpc 
B)  170 Mpc 
C)  230 Mpc 
D)  280 Mpc 
E)  340 Mpc

Question 2

What do astronomers mean when they say that the universe is homogeneous?

Accepted Answer

A)  All stars in all galaxies have planetary systems just like ours. 
B)  The universe looks exactly the same no matter what place you look. 
C)  Galaxies are generally distributed similarly throughout the universe. 
D)  Generally speaking, there is little difference between conditions on Earth, in the Sun, or in outer space. 
E)  The universe looks the same at all times in its history. 
A)  All stars in all galaxies have planetary systems just like ours. 
B)  The universe looks exactly the same no matter what place you look. 
C)  Galaxies are generally distributed similarly throughout the universe. 
D)  Generally speaking, there is little difference between conditions on Earth, in the Sun, or in outer space. 
E)  The universe looks the same at all times in its history.

Question 3

Hubble's constant, H0, represents:

Accepted Answer

A)  the rate of expansion of the universe 
B)  the speed at which galaxies are moving away from us 
C)  the time it takes a galaxy to move twice as far away from us 
D)  the size of the universe 
E)  the amount of time since the Solar System formed 
A)  the rate of expansion of the universe 
B)  the speed at which galaxies are moving away from us 
C)  the time it takes a galaxy to move twice as far away from us 
D)  the size of the universe 
E)  the amount of time since the Solar System formed

Question 4

What is the interpretation of a redshift larger than 1?

Accepted Answer

A)  The object is moving faster than the speed of light. 
B)  The universe has more than doubled in size since the light from that object was emitted. 
C)  The object has an extremely large peculiar velocity. 
D)  The light was shifted to longer wavelengths from gravitational radiation. 
E)  The rate of expansion of the universe is increasing. 
A)  The object is moving faster than the speed of light. 
B)  The universe has more than doubled in size since the light from that object was emitted. 
C)  The object has an extremely large peculiar velocity. 
D)  The light was shifted to longer wavelengths from gravitational radiation. 
E)  The rate of expansion of the universe is increasing.

Question 5

Why can Type I supernovae be used to determine a galaxy's distance?

Accepted Answer

A)  Type I supernovae occur only in very luminous galaxies. 
B)  Type I supernovae have approximately the same luminosity. 
C)  Type I supernovae have approximately the same size. 
D)  A Type I supernova occurs in a typical galaxy about once every 100 years. 
E)  Type I supernovae occur even in very small galaxies. 
A)  Type I supernovae occur only in very luminous galaxies. 
B)  Type I supernovae have approximately the same luminosity. 
C)  Type I supernovae have approximately the same size. 
D)  A Type I supernova occurs in a typical galaxy about once every 100 years. 
E)  Type I supernovae occur even in very small galaxies.

Question 6

Which of the following was NOT created as a result of Big Bang nucleosynthesis?

Accepted Answer

A)  helium 
B)  lithium 
C)  hydrogen 
D)  deuterium 
E)  carbon 
A)  helium 
B)  lithium 
C)  hydrogen 
D)  deuterium 
E)  carbon

Question 7

Why are some galaxies' spectra blueshifted rather than redshifted?

Accepted Answer

A)  Some distant galaxies are gravitationally lensed. 
B)  Some distant galaxies show the universe was contracting before the Big Bang started. 
C)  Some nearby galaxies have vigorous star formation and are much bluer than others. 
D)  Some distant galaxies have AGN at their centers. 
E)  Some nearby galaxies have small peculiar velocities in our direction. 
A)  Some distant galaxies are gravitationally lensed. 
B)  Some distant galaxies show the universe was contracting before the Big Bang started. 
C)  Some nearby galaxies have vigorous star formation and are much bluer than others. 
D)  Some distant galaxies have AGN at their centers. 
E)  Some nearby galaxies have small peculiar velocities in our direction.

Question 8

According to Hubble's law, as the distance of a galaxy __________ its __________ increases.

Accepted Answer

A)  increases; luminosity 
B)  increases; recessional velocity 
C)  decreases; luminosity 
D)  decreases; recessional velocity 
E)  decreases; peculiar velocity 
A)  increases; luminosity 
B)  increases; recessional velocity 
C)  decreases; luminosity 
D)  decreases; recessional velocity 
E)  decreases; peculiar velocity

Question 9

If the Hubble constant had a value that was half of its current measured value of 70 km/s/Mpc, the age of the Universe would be about

Accepted Answer

A)  7 billion years 
B)  14 billion years 
C)  22 billion years 
D)  27 billion years 
E)  33 billion years 
A)  7 billion years 
B)  14 billion years 
C)  22 billion years 
D)  27 billion years 
E)  33 billion years

Question 10

The spectrum of a galaxy is observed to have an H$\alpha$emission line at a wavelength of 928.7 nm. What is its redshift? Note that the rest wavelength of the H$\alpha$ emission line is 656.3 nm.

Accepted Answer

z = (@#LAT-DLM&_obs-@#LAT-DLM&_rest<

Question 11

When we look at galaxies in the universe and measure their star formation rates, we find that galaxies at redshifts z $\approx$ 1 have higher star formation rates than they do now. At that time, the universe was __________ times the size it is today.

Accepted Answer

A)  0.1 
B)  0.2 
C)  0.5 
D)  0.7 
E)  0.90 
A)  0.1 
B)  0.2 
C)  0.5 
D)  0.7 
E)  0.90

Question 12

What did Edwin Hubble study in the Andromeda Galaxy that proved it was an individual galaxy and not part of our own Milky Way?

Accepted Answer

A)  Cepheid stars 
B)  Type I supernovae 
C)  globular clusters 
D)  red giant stars 
E)  RR Lyrae variables 
A)  Cepheid stars 
B)  Type I supernovae 
C)  globular clusters 
D)  red giant stars 
E)  RR Lyrae variables

Question 13

What important event in the universe's history marked the creation of the cosmic background radiation?

Accepted Answer

The CMB is a relic of the time in the un

Question 14

The cosmological principle says physical laws that the universe is homogeneous and isotropic.

Accepted Answer

A) True 
 B)False

Question 15

Describe the two assumptions regarding the universe that the cosmological principle makes.

Accepted Answer

(1) The universe is homogeneou

Question 16

It is possible for a galaxy to have an apparent recessional velocity greater than the speed of light.

Accepted Answer

A) True 
 B)False

Question 17

The Hubble Space Telescope can be used to study galaxies at a redshift equal to 2. How much has the universe expanded since that the light was emitted from these galaxies?

Accepted Answer

The expansion factor at z = 2

Question 18

To be a standard candle, an object must have a constant:

Accepted Answer

A)  lifetime 
B)  brightness 
C)  luminosity 
D)  distance 
E)  mass 
A)  lifetime 
B)  brightness 
C)  luminosity 
D)  distance 
E)  mass

Question 19

The standard Big Bang theory successfully predicts that the fraction of helium by mass in the primordial universe was 2 percent, similar to what it is in the Sun.

Accepted Answer

A) True 
 B)False

Question 20

Does the temperature of the cosmic background radiation tell us about the age of the universe?

Accepted Answer

A)  Yes, since it was produced at a redshift of approximately 1,000. 
B)  No, we still need to know the Hubble constant to know the universe's age. 
C)  No, the temperature does not but the size of temperature variations in the CMB does tell us the age. 
D)  Yes, in combination with information on cosmic nucleosynthesis. 
E)  No, the CMB formed at a wide variety of times and gives no information on the age of the whole universe. 
A)  Yes, since it was produced at a redshift of approximately 1,000. 
B)  No, we still need to know the Hubble constant to know the universe's age. 
C)  No, the temperature does not but the size of temperature variations in the CMB does tell us the age. 
D)  Yes, in combination with information on cosmic nucleosynthesis. 
E)  No, the CMB formed at a wide variety of times and gives no information on the age of the whole universe.

Exam 19: The Expanding Universe

In the figure shown below, the upper spectrum is from hydrogen at rest in a laboratory, and the lower spectrum is from a galaxy. How far away is this galaxy?

What do astronomers mean when they say that the universe is homogeneous?

Hubble's constant, H0, represents:

What is the interpretation of a redshift larger than 1?

Why can Type I supernovae be used to determine a galaxy's distance?

Which of the following was NOT created as a result of Big Bang nucleosynthesis?

Why are some galaxies' spectra blueshifted rather than redshifted?

According to Hubble's law, as the distance of a galaxy __________ its __________ increases.

If the Hubble constant had a value that was half of its current measured value of 70 km/s/Mpc, the age of the Universe would be about

The spectrum of a galaxy is observed to have an H α\alphaα emission line at a wavelength of 928.7 nm. What is its redshift? Note that the rest wavelength of the H α\alphaα emission line is 656.3 nm.

When we look at galaxies in the universe and measure their star formation rates, we find that galaxies at redshifts z ≈\approx≈ 1 have higher star formation rates than they do now. At that time, the universe was __________ times the size it is today.

What did Edwin Hubble study in the Andromeda Galaxy that proved it was an individual galaxy and not part of our own Milky Way?

What important event in the universe's history marked the creation of the cosmic background radiation?

The cosmological principle says physical laws that the universe is homogeneous and isotropic.

Describe the two assumptions regarding the universe that the cosmological principle makes.

It is possible for a galaxy to have an apparent recessional velocity greater than the speed of light.

The Hubble Space Telescope can be used to study galaxies at a redshift equal to 2. How much has the universe expanded since that the light was emitted from these galaxies?

To be a standard candle, an object must have a constant:

The standard Big Bang theory successfully predicts that the fraction of helium by mass in the primordial universe was 2 percent, similar to what it is in the Sun.

Does the temperature of the cosmic background radiation tell us about the age of the universe?

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

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 Liquid the Giant Planets

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters

Hubble's constant, H₀, represents:

According to Hubble's law, as the distance of a galaxy its increases.

The spectrum of a galaxy is observed to have an H $\alpha$ emission line at a wavelength of 928.7 nm. What is its redshift? Note that the rest wavelength of the H $\alpha$ emission line is 656.3 nm.

When we look at galaxies in the universe and measure their star formation rates, we find that galaxies at redshifts z $\approx$ 1 have higher star formation rates than they do now. At that time, the universe was __________ times the size it is today.