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Chapter 28
The Sun
Review
Choose the best response. Write the letter of that choice in the space provided.
1. According to Einstein’s theory of relativity, in the formula E = mc2, the c stands for
a. corona.
c. the speed of light.
b. core.
d. the length of time.
2. A nuclear reaction in which two atomic nuclei combine is called
a. fission.
b. fusion.
c. magnetism.
d. granulation.
3. The portion of the sun in which energy moves from atom to atom in the form of waves is
called the
a. radiative zone. b. convective zone.
c. solar wind.
d. chromosphere.
4. The portion of the sun normally visible from the earth is the
a. core.
b. photosphere.
c. corona.
d. solar nebula.
b. 5 years.
c. 11 years.
d. 19 years.
5. The sunspot cycle lasts
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a. 2 years.
6. Sudden outward eruptions of electrically charged atomic particles from the sun are called
a. planetesimals.
b. coronas.
c. sunspots.
d. solar flares.
c. nuclear fission.
d. nuclear fusion.
7. Gusts of solar wind can cause
a. protoplanets.
b. magnetic storms.
8. Northern lights and southern lights are other names for
a. prominences.
b. auroras.
c. granulations.
d. protoplanets.
9. The hypothesis that the sun and the planets developed out of the same cloud of gas and
dust is called the
a. nebular theory.
c. nuclear theory.
b. theory of relativity.
d. theory of convection.
10. The small bodies of matter that filled the solar nebula are called
a. protoplanets.
b. planetesimals.
c. auroras.
d. proton nuclei.
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Chapter 28
Choose the best response. Write the letter of that choice in the space provided.
11. Compared with the size of the present-day planets, the protoplanets were
a. much smaller.
b. slightly smaller. c. similar.
d. larger.
12. The first atmosphere of the earth had a high percentage of
a. helium.
b. oxygen.
c. nitrogen.
d. water vapor.
13. In the process of photosynthesis, cyanobacteria and green plants give off
a. oxygen.
b. carbon dioxide. c. hydrogen.
d. helium.
14. Water vapor began to condense into oceans about
a. 1 million to 1.5 million years ago.
c. 3 billion to 3.5 billion years ago.
b. 1 billion to 1.5 billion years ago.
d. 15 billion to 15.5 billion years ago.
Critical Thinking
Read each question or statement and answer it in the space provided.
1. Explain how the transfer of energy in a pan of hot water is similar to the transfer of energy in
the sun’s convective zone.
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2. Predict what would happen to the number of sunspots if the sun’s magnetic field suddenly
increased in strength.
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Chapter 28
Read each question or statement and answer it in the space provided.
3. If the earth’s magnetosphere shifted, what would happen to the area where auroras are most
often visible?
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4. How would the layers of the earth be different if the planet had never been hotter than it is today?
5. How would the atmosphere of the earth be different if the earth had formed from a much larger
protoplanet?
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Chapter 28
Application
Read each question or statement and answer it in the space provided.
1. You are asked to explain the following statement to an elementary school class: Solar hydrogen
is responsible for life existing on the earth. What would you say?
2. A group of senior citizens has decided to head north to view the northern lights. When would
you advise them to go in order to see the most frequent displays?
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3. Using the new terms listed on page 586 of your textbook, construct a concept map that, among
other things, illustrates the path of energy from the core of the sun to the far side of the earth.
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Pages 582–583: Career Focus
To stimulate students’ interest in astronomy as a
career, discuss how the role of astronomers in society is changing. Point out the growing importance of
outer space for business, communications, and scientific research.
Pages 582–585: Discussion (Extension)
To extend students’ understanding of how earth conditions favored the development of life, have students consider the size of the earth. If the earth had
been smaller, it would not have been able to hold
oxygen in its atmosphere. Without oxygen, life
would not have developed. You might also discuss
the influence of temperature and of the presence of
water on the development of life on the earth.
Page 585: EarthBeat
To help students understand the solar constant,
explain that astronomers simplify its measurement
by disregarding the effects of the earth’s atmosphere
and the angle of the sun’s rays striking the earth.
Small-Scale Investigation
Chapter 28 Review
Answers to Review
1. c
2. b
3. a
4. b
5. c
6. d
7. b
8. b
9. a
10. b
11. d
12. a
13. a
14. c
Answers to Critical Thinking
1. In the pan, energy is transferred toward the surface by moving liquid. In the sun’s convective
zone, energy is transferred from the core toward
the surface by moving gases. Both of these two
energy transfers are examples of convection.
2. They would probably increase.
3. The area would shift, along with the shift in the
magnetic poles.
4. The iron would not have flowed to the core of
the earth, so the layers of the earth would be less
distinct.
5. The earth would have kept more of the hydrogen
and helium that were part of its first atmosphere.
Answers to Application
Solar Viewer (p. 573)
Science Process Skills: observing, describing, comparing, measuring
Answers to Analysis and Conclusions
1. Yes. As the distance between the pinhole and the
card increases, the image becomes larger and
fainter. As the distance decreases, the image
becomes smaller and brighter.
2. As the pinhole is made larger, the image becomes
larger and less distinct. The edges of the image
get more and more diffuse until the hole is so
large that no clear image forms.
3. The solar viewer works primarily because the sun
is so bright. Like a solar telescope, the pinhole
gathers light and projects an image. Unlike a
solar telescope, the solar viewer does not magnify the projected image.
T136 Chapter 28
1. Hydrogen is the source of the sun’s energy, and
the sun’s energy is necessary for life on earth to
exist.
2. They should plan to take their trip just after the
peak of a sunspot cycle or following a solar flare.
3. Student concept maps should connect terms with
appropriate links to illustrate the generation of
the sun’s energy from the core, through the sun’s
layers, reflecting from the moon, to the far side
of the earth.
In-Depth Investigation
Size and Energy of the Sun (pp. 588–589)
Approximate time: 1 class period
Objectives: to perform a simple experiment from
which the sun’s diameter can be calculated; to
collect energy from sunlight and estimate the
amount of energy produced by the sun
Skills: observing, measuring, calculating, inferring,
predicting