Question 1

What do we mean when we say that the Sun is in gravitational equilibrium?

Accepted Answer

A)  The hydrogen gas in the Sun is balanced so that it never rises upward or falls downward.
B)  The Sun maintains a steady temperature.
C)  This is another way of stating that the Sun generates energy by nuclear fusion.
D)  There is a balance within the Sun between the outward push of pressure and the inward pull of gravity.
E)  The Sun always has the same amount of mass,creating the same gravitational force.F) B) and E)
G) A) and C)

Question 2

Why must the Sun's rate of fusion gradually rise over billions of years?

Accepted Answer

A)  The Sun becomes less efficient and must increase the rate of fusion to produce the same amount of energy.
B)  Fusion reactions decrease the overall number of particles in the core,causing the core to shrink,converting gravitational potential energy into thermal energy,and increasing the rate of fusion.
C)  The radiation produced by fusion reactions that is trapped in the core gradually raises the temperature,increasing the rate of fusion.
D)  The Sun gets heavier as it gets older,and the stronger inward pull of gravity increases the fusion rate.
E)  The rate of fusion is not rising;it is actually decreasing over time.F) B) and C)
G) B) and D)

Question 3

When is/was gravitational contraction an important energy-generation mechanism for the Sun?

Accepted Answer

A)  only during solar minimum
B)  only during solar maximum
C)  when the Sun was being formed from a collapsing cloud of gas
D)  right after the Sun began fusing hydrogen in its core
E)  when the Sun transports radiation through the convection zoneF) None of the above
G) D) and E)

Question 4

Why are neutrinos so difficult to detect?

Accepted Answer

A)  because there are so rare
B)  because they have no mass
C)  because they move at nearly the speed of light
D)  because they rarely interact with matter
E)  because they are so smallF) C) and D)
G) D) and E)

Question 5

Which statement best describes the solar neutrino problem?

Accepted Answer

A)  Theoretical models predict that neutrinos should be produced in the Sun,but no neutrinos have ever been observed to be coming from the Sun.
B)  Solar neutrinos were detected but in fewer numbers than predicted by theoretical models.
C)  No one understands how it can be possible for neutrinos to be produced in the Sun.
D)  Our current understanding of fusion in the Sun suggests that all neutrinos should be destroyed before they arrive at Earth,yet neutrinos are being detected.
E)  The term solar neutrino problem refers to the fact that neutrinos are extremely difficult to detect.F) A) and B)
G) None of the above

Question 6

According to modern science,approximately how old is the Sun?

Accepted Answer

A)  4  12 \frac{1}{2} 21​  billion years
B)  25 million years
C)  10,000 years
D)  400 million years E) A) and D)
F) All of the above

Question 7

Which of the following best explains why nuclear fusion requires bringing nuclei extremely close together?

Accepted Answer

A)  Nuclei normally repel because they are all positively charged and can be made to stick only when brought close enough for the strong force to take hold.
B)  Nuclei are attracted to each other by the electromagnetic force,but this force is only strong enough to make nuclei stick when they are very close together.
C)  Nuclei have to be very hot in order to fuse,and the only way to get them hot is to bring them close together.
D)  Fusion can proceed only by the proton-proton chain,and therefore requires that protons come close enough together to be linked up into a chain.E) A) and B)
F) B) and D)

Question 8

Which is closest to the temperature of the core of the Sun?

Accepted Answer

A)  10,000 K
B)  100,000 K
C)  1 million K
D)  10 million K
E)  100 million KF) D) and E)
G) B) and C)

Question 9

What observations characterize solar maximum?

Accepted Answer

A)  The Sun becomes much brighter.
B)  The Sun emits light of longer average wavelength.
C)  The Sun rotates faster at the equator.
D)  We see many sunspots on the surface of the Sun.
E)  all of the aboveF) C) and D)
G) D) and E)

Question 10

The intricate patterns visible in an X-ray image of the Sun generally show

Accepted Answer

A)  helioseismological fluctuations.
B)  a bubbling pattern on the photosphere.
C)  extremely hot plasma flowing along magnetic field lines.
D)  structure within sunspots.E) None of the above
F) All of the above

Question 11

What is the Sun made of (by mass) ?

Accepted Answer

A)  70% hydrogen,28% helium,2% other elements
B)  100% hydrogen and helium
C)  50% hydrogen,25% helium,25% other elements
D)  90% dark matter,10% ordinary matterE) A) and B)
F) All of the above

Question 12

Process of Science: How do we know what is going on in the center of the Sun so well if we cannot see it or send spacecraft to it?

Accepted Answer

We can apply our knowledge of how gases ...

Question 13

In the late 1800s,Kelvin and Helmholtz suggested that the Sun stayed hot due to gravitational contraction.What was the major drawback to this idea?

Accepted Answer

A)  It predicted that the Sun would shrink noticeably as we watched it,but the Sun appears to be stable in size.
B)  It is physically impossible to generate heat simply by making a star shrink in size.
C)  It predicted that the Sun could shine for about 25 million years,but geologists had already found that Earth is much older than this.
D)  It predicted that Earth would also shrink in size with time,which would make it impossible to have stable geology on our planet.E) None of the above
F) A) and B)

Question 14

What is the solution to the solar neutrino problem?

Accepted Answer

A)  The Sun is generating energy other than by nuclear fusion.
B)  The Sun is generating much less energy than we think it is.
C)  We do not know how to detect electron neutrinos.
D)  Not all fusion reactions create electron neutrinos.
E)  The electron neutrinos created in the Sun change into another type of neutrino that we could not detect with our original equipment.F) D) and E)
G) A) and B)

Question 15

Might changes in the Sun affect weather or climate on Earth?

Accepted Answer

During the last Maunder minimum period,t...

Question 16

Why does the Sun emit neutrinos?

Accepted Answer

A)  Solar flares create neutrinos with magnetic fields.
B)  Fusion in the Sun's core creates neutrinos.
C)  Convection releases neutrinos,which random walk through the radiation zone.
D)  The Sun was born with a supply of neutrinos that it gradually emits into space.
E)  The Sun does not emit neutrinos.F) A) and B)
G) A) and C)

Question 17

Although the Sun does not generate energy by gravitational contraction today,this energy-generation mechanism was important when the Sun was forming.

Accepted Answer

A) True 
 B)False

Question 18

How is the sunspot cycle directly relevant to us here on Earth?

Accepted Answer

A)  The sunspot cycle strongly influences Earth's weather.
B)  The Sun's magnetic field,which plays a major role in the sunspot cycle,affects compass needles that we use on Earth.
C)  The brightening and darkening of the Sun that occurs during the sunspot cycle affects plant photosynthesis here on Earth.
D)  Coronal mass ejections and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment.
E)  The sunspot cycle is the cause of global warming.F) C) and E)
G) B) and C)

Question 19

The chromosphere is the layer of the Sun that we see as its visible surface.

Accepted Answer

A) True 
 B)False

Question 20

Why do sunspots appear dark in pictures of the Sun?

Accepted Answer

A)  They are too cold to emit any visible light.
B)  They are holes in the solar surface through which we can see through to deeper,darker layers of the Sun.
C)  They are extremely hot and emit all their radiation as X-rays rather than visible light.
D)  They actually are fairly bright,but appear dark against the even brighter background of the surrounding photosphere.E) C) and D)
F) A) and B)

Exam 14: Our Star

What is the Sun made of (by mass) ?

Correct AnswerverifiedShow Answer

Why are neutrinos so difficult to detect?

Correct AnswerverifiedShow Answer

Why does the Sun emit neutrinos?

Correct AnswerverifiedShow Answer

How is the sunspot cycle directly relevant to us here on Earth?

Correct AnswerverifiedShow Answer

When is/was gravitational contraction an important energy-generation mechanism for the Sun?

Correct AnswerverifiedShow Answer

Why do sunspots appear dark in pictures of the Sun?

Correct AnswerverifiedShow Answer

What observations characterize solar maximum?

Correct AnswerverifiedShow Answer

Which is closest to the temperature of the core of the Sun?

Correct AnswerverifiedShow Answer

What is the solution to the solar neutrino problem?

Correct AnswerverifiedShow Answer

The chromosphere is the layer of the Sun that we see as its visible surface.

Correct AnswerverifiedShow Answer

Although the Sun does not generate energy by gravitational contraction today,this energy-generation mechanism was important when the Sun was forming.

Correct AnswerverifiedShow Answer

Might changes in the Sun affect weather or climate on Earth?

Correct AnswerverifiedDuring the last Maunder minimum period,t...View AnswerShow Answer

What do we mean when we say that the Sun is in gravitational equilibrium?

Correct AnswerverifiedShow Answer

Which of the following best explains why nuclear fusion requires bringing nuclei extremely close together?

Correct AnswerverifiedShow Answer

The intricate patterns visible in an X-ray image of the Sun generally show

Correct AnswerverifiedShow Answer

Why must the Sun's rate of fusion gradually rise over billions of years?

Correct AnswerverifiedShow Answer

According to modern science,approximately how old is the Sun?

Correct AnswerverifiedShow Answer

Process of Science: How do we know what is going on in the center of the Sun so well if we cannot see it or send spacecraft to it?

Correct AnswerverifiedWe can apply our knowledge of how gases ...View AnswerShow Answer

Which statement best describes the solar neutrino problem?

Correct AnswerverifiedShow Answer

In the late 1800s,Kelvin and Helmholtz suggested that the Sun stayed hot due to gravitational contraction.What was the major drawback to this idea?

Correct AnswerverifiedShow Answer

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During the last Maunder minimum period,t...
View Answer

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We can apply our knowledge of how gases ...
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