Question 1

The cosmic background radiation (CBR)has a temperature of approximately 2.7 K and a Planck blackbody spectrum.Calculate the wavelength where the CBR spectrum peaks.

Accepted Answer

The answer of The cosmic background radiation (CBR)has a temperature...

Question 2

After the Big Bang,as the universe cooled and protons and electrons combined so that the universe become neutral,what important consequence happened?

Accepted Answer

A)  Photons began to travel freely through the universe. 
B)  Neutrinos ceased to interact with normal matter. 
C)  Dark matter ceased to interact with normal matter. 
D)  Protons and neutrons combined to form nuclei such as deuterium and helium. 
A)  Photons began to travel freely through the universe. 
B)  Neutrinos ceased to interact with normal matter. 
C)  Dark matter ceased to interact with normal matter. 
D)  Protons and neutrons combined to form nuclei such as deuterium and helium. A

Question 3

Which of the following is NOT a prediction of the standard Big Bang theory that has been successfully verified by observations?

Accepted Answer

A)  The universe is expanding. 
B)  The faintest galaxies look redder because their stars are younger. 
C)  Helium,lithium,and beryllium were made as the universe cooled after the initial Big Bang. 
D)  The early universe was very hot and dense. 
A)  The universe is expanding. 
B)  The faintest galaxies look redder because their stars are younger. 
C)  Helium,lithium,and beryllium were made as the universe cooled after the initial Big Bang. 
D)  The early universe was very hot and dense. B

Question 4

If the distance of a galaxy is 100 Mly,what is its recessional velocity if the Hubble constant is 22 km/s/Mly?

Accepted Answer

A)  100 km/s 
B)  220 km/s 
C)  1,000 km/s 
D)  2,200 km/s 
A)  100 km/s 
B)  220 km/s 
C)  1,000 km/s 
D)  2,200 km/s

Question 5

If you measured the distances and recessional velocities for a sample of galaxies and plotted the data to get the figure below,what value would you derive for the Hubble constant?

Accepted Answer

A)  10 km/s/Mly 
B)  22 km/s/Mly 
C)  45 km/s/Mly 
D)  100 km/s/Mly 
A)  10 km/s/Mly 
B)  22 km/s/Mly 
C)  45 km/s/Mly 
D)  100 km/s/Mly

Question 6

If there were more baryons in the universe immediately after the Big Bang,then the abundance of __________ in stars and galaxies would be higher.

Accepted Answer

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

Question 7

Assuming the Hubble constant is equal to 22 km/s/Mly,estimate the age of the universe (or Hubble time).Note that   and   .

Accepted Answer

The answer of Assuming the Hubble constant is equal to...

Question 8

The apparent recessional velocities of galaxies at large distances are due mainly to the actual motions of the galaxies through space.

Accepted Answer

A) True 
 B)False

Question 9

The abundance of various elements formed from Big Bang nucleosynthesis depended only on the temperature of normal matter in the early universe.

Accepted Answer

A) True 
 B)False

Question 10

If a galaxy has a recessional velocity of 880 km/s,what is its distance if the Hubble constant is 22 km/s/Mly?

Accepted Answer

A)  40 Mly 
B)  88 Mly 
C)  400 Mly 
D)  8,800 Mly 
A)  40 Mly 
B)  88 Mly 
C)  400 Mly 
D)  8,800 Mly

Question 11

The Sun is 27 percent helium by mass.Where was the majority of this helium manufactured?

Accepted Answer

A)  In Type II supernovae explosions that happened before the Sun formed 
B)  In low-mass stars that lived and died before the Sun formed 
C)  In nuclear burning that happened in the Sun's core 
D)  In the Big Bang 
A)  In Type II supernovae explosions that happened before the Sun formed 
B)  In low-mass stars that lived and died before the Sun formed 
C)  In nuclear burning that happened in the Sun's core 
D)  In the Big Bang

Question 12

In the Great Debate of 1920,Curtis and Shapley argued over whether or not

Accepted Answer

A)  the Big Bang occurred. 
B)  the age of the universe was 14 billion years. 
C)  the spiral nebulae were located outside the Milky Way. 
D)  life existed outside of Earth. 
A)  the Big Bang occurred. 
B)  the age of the universe was 14 billion years. 
C)  the spiral nebulae were located outside the Milky Way. 
D)  life existed outside of Earth.

Question 13

What caused early astronomers to believe that our galaxy is only about 6,000 light-years across?

Accepted Answer

A)  Telescopes were not powerful enough to observe stars farther away. 
B)  Interstellar dust blocked visible light from stars farther away. 
C)  Stars farther away could not be resolved as individual objects. 
D)  Astronomers miscalculated the distances to stars,believing that the stars were 50 times closer than they actually were. 
A)  Telescopes were not powerful enough to observe stars farther away. 
B)  Interstellar dust blocked visible light from stars farther away. 
C)  Stars farther away could not be resolved as individual objects. 
D)  Astronomers miscalculated the distances to stars,believing that the stars were 50 times closer than they actually were.

Question 14

Galaxies move away from us in all directions because

Accepted Answer

A)  the force of gravity strengthens with distance. 
B)  the force of gravity weakens with distance. 
C)  space is expanding. 
D)  our galaxy has expelled all other galaxies. 
A)  the force of gravity strengthens with distance. 
B)  the force of gravity weakens with distance. 
C)  space is expanding. 
D)  our galaxy has expelled all other galaxies.

Question 15

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

Accepted Answer

A)  Helium 
B)  Lithium 
C)  Carbon 
D)  Deuterium 
A)  Helium 
B)  Lithium 
C)  Carbon 
D)  Deuterium

Question 16

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

Accepted Answer

The universe is homogeneous (t

Question 17

The most distant galaxies we can see today have a redshift of   when the universe was

Accepted Answer

A)  3 times smaller than it is today. 
B)  7 times smaller than it is today. 
C)  12 times smaller than it is today. 
D)  the same size as it is today. 
A)  3 times smaller than it is today. 
B)  7 times smaller than it is today. 
C)  12 times smaller than it is today. 
D)  the same size as it is today.

Question 18

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

Question 19

Does Hubble's law imply that our galaxy is sitting at the center of the universe? Explain.

Accepted Answer

Our galaxy is not at the center of the u

Question 20

Which distance indicator can be used to measure the most distant objects?

Accepted Answer

A)  Cepheids 
B)  Parallax 
C)  Type I supernovae 
D)  Main-sequence fitting 
A)  Cepheids 
B)  Parallax 
C)  Type I supernovae 
D)  Main-sequence fitting

Exam 18: Our Expanding Universe

The cosmic background radiation (CBR)has a temperature of approximately 2.7 K and a Planck blackbody spectrum.Calculate the wavelength where the CBR spectrum peaks.

After the Big Bang,as the universe cooled and protons and electrons combined so that the universe become neutral,what important consequence happened?

Which of the following is NOT a prediction of the standard Big Bang theory that has been successfully verified by observations?

If the distance of a galaxy is 100 Mly,what is its recessional velocity if the Hubble constant is 22 km/s/Mly?

If you measured the distances and recessional velocities for a sample of galaxies and plotted the data to get the figure below,what value would you derive for the Hubble constant?

If there were more baryons in the universe immediately after the Big Bang,then the abundance of __________ in stars and galaxies would be higher.

Assuming the Hubble constant is equal to 22 km/s/Mly,estimate the age of the universe (or Hubble time).Note that and .

The apparent recessional velocities of galaxies at large distances are due mainly to the actual motions of the galaxies through space.

The abundance of various elements formed from Big Bang nucleosynthesis depended only on the temperature of normal matter in the early universe.

If a galaxy has a recessional velocity of 880 km/s,what is its distance if the Hubble constant is 22 km/s/Mly?

The Sun is 27 percent helium by mass.Where was the majority of this helium manufactured?

In the Great Debate of 1920,Curtis and Shapley argued over whether or not

What caused early astronomers to believe that our galaxy is only about 6,000 light-years across?

Galaxies move away from us in all directions because

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

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

The most distant galaxies we can see today have a redshift of when the universe was

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

Does Hubble's law imply that our galaxy is sitting at the center of the universe? Explain.

Which distance indicator can be used to measure the most distant objects?

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

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

The Origin of Structure

Life

Filters

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