Download Skinner Chapter 3

Fall 2000
Lohrengel
Geology 1013 - Earth System Science
Chapter 3 Questions
Instructions:
Read each question carefully before answering. Work at a steady pace, and you should
have ample time to finish.
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1. The Sun is thought to be a fairly homogeneous body, with no internal
structure or layering.
2. Life cannot exist on Venus and Mars primarily because they are too
cold.
3. The Sun is compositionally layered, with a small rocky core inside
the gigantic outer shell of gas.
4. Unlike the Earth and some of the other planets, the Sun has no
magnetic field.
5. All telescopes work by gathering and concentrating electromagnetic
radiation in the form of visible light.
6. Visible light is a form of electromagnetic radiation.
7. The radiative and convective layers of the Sun have approximately
the same composition as that of the planet Jupiter.
8. The Sun is a nearly perfect blackbody radiator.
9. The photosphere is the outermost layer of the Sun, from which is
emitted the light that reaches the Earth.
10. Our Sun will finish its evolutionary sequence as a black dwarf in
about 4 to 5 billion years.
11. The death of a small- mass star, 0.25 times the mass of our own Sun,
is
a. much more common than the very dramatic supernova explosions that
occur at the deaths of more massive stars.
b. not observable because these stars are very long- lived, and the
universe is too young for any of them to have evolved off the
main sequence.
c. similar to the death of a 1-S star.
d. the process whereby elements heavier than carbon are created.
12. Which one of the following statements is false?
a. Our Sun is in its hydrogen burning stage of evolution.
b. The main sequence lifetime of our Sun will last at least 4
billion more years.
c. After our Sun has exhausted its nuclear "fuel," its outer layers
will erupt explosively as a supernova.
d. The Sun has inherited virtually all elements with masses greater
than helium from earlier generations of stars.
13. Stars are masses of material of such enormous density
a. that nuclear fission occurs at their cores.
b. because they have iron- nickel cores.
c. that nuclear fusion occurs at their cores.
d. None of these is true.
14. The radius of the Sun is hard to determine accurately because
a. the Sun is so far away.
b. it is constantly changing.
c. it is so enormous compared with other bodies in the solar system.
d. it is hard to define the outer edge of a ball of gas.
15. There are about _______________ galaxies in the universe.
a. 100 billion (10 1 1)
b. 100 billion billion (10 2 0)
c. 1 billion (10 9)
d. 100 million (10 8)
16. Because of its distance from the Sun, the Earth receives just the
right amount of light and heat to support life, but ____________
and ____________ are too hot and dry for life to exist.
a. the Moon and Mars
b. Mars and Venus
c. Venus and Mercury
d. the Moon and Mercury
17. The death of a giant star, five times as massive as our own, occurs
as a
a. quiet burning out and core contraction due to no more remaining
nuclear fuel.
b. violent transition into a white dwarf.
c. transition to a red giant, and then a white dwarf.
d. supernova explosion.
18. Nuclear fusion
a. converts some of the mass of an atom into energy.
b. has only been achieved in an uncontrolled manner (in hydrogen
bombs) on Earth.
c. represents a potentially limitless energy source for society, if
it can be achieved under controlled conditions.
d. All of these are true.
19. In order to calculate the Sun's luminosity, scientists must first
a. measure the energy flux reaching the Earth from the Sun.
b. know the surface area of the Earth's sphere.
c. calculate what fraction of the Sun's luminosity is received by
the Earth.
d. All of these are true.
20. Earth receives a tiny fraction, only about one ___________ of the
Sun's total energy output.
a. half
b. 2 thousandth
c. 2 millionth
d. 2 billionth
21. The PP chain and the CNO chain
a. are the two main types of energy-producing fusion reactions in
the Sun and most other stars.
b. both involve the fusion of hydrogen nuclei to form helium plus
energy.
c. have the same net result, but different intermediate steps.
d. All of these are true.
e. None of these is true.
22. Which one of the following is not one of the three essential
properties of electromagnetic waves?
a. wavelength
b. frequency
c. direction
d. speed
23. Gamma rays (‚) are
a. a form of highly energetic, short-wavelength electromagnetic
radiation.
b. similar to neutrinos, and together these two forms of radiation
are responsible for the transfer of energy from the Sun to the
Earth.
c. generated in the core of the Sun and then absorbed in the
photosphere, which slows down the transfer of energy from the
Sun.
d. produced by fission reactions in the core of the Sun.
24. A neutrino is
a. an essentially massless particle that moves at the speed of
light.
b. part of the basic internal structure of a hydrogen atom.
c. the major form in which solar electromagnetic radiation reaches
the Earth.
d. a negatively charged electromagnetic particle.
25. Which one of the following is not a stage in the life cycle of a
1-S star?
a. red giant
b. black dwarf
c. black hole
d. white dwarf
e. main sequence
26. The Sun's corona is
a. made of a very dense gas.
b. only observable during a solar eclipse.
c. the part of the Sun from which is emitted the light that reaches
the Earth.
d. All of these are true.
27. Active regions in the Sun are probably caused by
a. auroras and sunspots.
b. turbulence due to sunspots and differential rotation.
c. turbulence due to differential rotation and magnetism.
d. short-term changes in the Sun's luminosity.
28. Star luminosity is
a. a function of both star temperature and star size.
b. greater for stars of greater mass.
c. the same as the observed or measured brightness of the star.
d. a function of the colour of the material of which the star is
composed.
29. On an H-R diagram, about 85 percent of stars fall on or close to a
smooth curve that astronomers refer to as the
a. life cycle curve.
b. active region.
c. main sequence.
d. core.
30. Blackbody radiators
a. are perfectly dark, and can only be detected through the use of
nonoptical telescopes.
b. absorb all light that strikes them, reflecting none.
c. show spectral curves that differ greatly from those of a brightly
glowing object such as the Sun.
d. All of these are true.
31. When the Sun burns out its nuclear fuel it will move off the main
sequence, first becoming a(n) ________________ and then ending up as
a(n) ________________.
32. The total amount of energy radiated outward each second by the Sun
or any other star is called the _______________.
33. The source of the Sun's energy is _________________.
34. A plot of star luminosity versus temperature is called a(n)
____________________.
35. When energy continuously passes through or continuously falls on a
unit area, we say there is an energy ______________ through or on
that area.
36. The Sun and most other stars produce their energy by two fusion
reactions: the ________________ chain and the _________________
chain.
37. Venus and Mercury are too _________________ for life to exist, and
Mars is too ________________.
38. When the path of a beam of light is bent in passing from one
transparent medium into another, it is referred to as _____________.
39. Visible light is just one small part of the _______________, an
arrangement of electromagnetic rays in order of decreasing or
increasing wavelength.
40. The energy created by fusion reactions in the Sun is produced in the
form of _______________ and ________________.
41. Why does the Sun appear to revolve around the Earth, when we know
that the opposite is true?
42. Briefly describe the characteristics of the Sun's three outermost
layers.
43. Make a neat, well- labelled diagram showing the internal structure of
the Sun.
44. In what way might the Sun's active periods directly influence
humans?
45. What are sunspots?
46. Both the planet Jupiter and the Sun consist primarily of hydrogen
and helium gas. What is the main difference between these two
bodies?
47. Briefly describe the characteristics of the Sun's radiative layer.
48. Why is Jupiter sometimes referred to as an "almost star"?
49. What is the difference between an optical telescope and a nonoptical
telescope?
50. The Sun is a near-perfect blackbody radiator. What does this mean?
51. Most of the time the Sun is relatively quiet, but sometimes it
develops active regions. What are the main causes of this?
52. What is a Hertzsprung-Russell diagram? Why are H-R diagrams
important tools in the study of stellar evolution? Where does the
Sun plot on the H-R diagram?
53. Describe the life cycle of a 1-S star.
54. How is the Principle of Uniformitarianism applied to the study of
star histories?
55. Describe how scientists measure changes in the Sun's luminosity. How
do you think changes in the Sun's luminosity might have affected the
climate on Earth throughout its history?
56. What is the electromagnetic spectrum, and what forms of light does
it contain?
57. Describe the process of shell fusion in a 1-S star.
58. Wha t is "parallax," and how does it help astronomers measure the
distances to stars?
_____________________________________________
Fall 2000
Lohrengel
Geology 1013 - Earth System Science
Answer Key: Chapter 3 Questions
1. F
2. F
3. F
4. F
5. F
6. T
7. T
8. T
9. F
10. T
11. B
12. C
13. C
14. D
15. A
16. C
17. D
18. D
19. A
20. D
21. D
22. C
23. A
24. A
25. C
26. B
27. C
28. A
29. C
30. B
31. red giant...white dwarf
32. luminosity
33. (nuclear fusion) OR (nuclear fusion in its core)
34. (Hertzsprung-Russell diagram) OR (H-R diagram)
35. flux
36. (proton-proton...carbon-nitrogen-oxygen) OR (PP...CNO)
37. (hot...cold) OR (hot & dry...cold & dry)
38. refraction
39. electromagnetic spectrum
40. gamma rays...neutrinos
41. The Sun appears to revolve around the Earth because of the Earth's
daily rotation about its axis, which makes the Sun seem to arc
across the sky from east to west every day. This is called apparent
motion.
42. The Sun's three outermost layers are called the photosphere, the
chromosphere, and the corona. The photosphere is an intensely
turbulent zone, which emits the light that reaches the Earth. The
chromosphere and corona are both low-density, transparent layers of
very hot gas; they are observable only during a solar eclipse.
43. [See Fig. 3.6 in the text.]
44. The Sun's active periods, manifested in the form of sunspots, are
thought to be related to cyclical changes caused by interactions
between the solar magnetic field and differential rotation. Because
the Sun's magnetic field influences the Earth's outer atmosphere,
many experts believe that sunspots influence the climate on the
Earth.
45. Sunspots are huge dark blotches on the surface of the Sun (actually,
on the surface of the photosphere). They appear dark because they
are relatively cool regions. The exact cause and mechanism of their
formation is not clearly understood, but they seem to occur in
cycles of about 11 years.
46. The Sun is considerably more massive than Jupiter, so temperatures
and pressures in the core of the Sun are high enough for nuclear
fusion to occur. Nuclear fusion does not occur in the core of
Jupiter.
47. Surrounding the Sun's core is a region that is very hot but not hot
enough for fusion to occur. This layer, called the radiative layer,
stretches from 170,000 to 590,000 km, measuring out from the center.
The energy released in the core moves across the radiative layer by
radiation, and it is this layer that makes the escape of energy from
the Sun a slow process. Electrons in the radiative layer absorb the
‚ radiation and make the layer opaque.
48. Masses smaller than about 0.1 S are too small for the temperature in
the core to get hot enough for nuclear fusion to start. Jupiter is
almost (but not quite) massive enough to have nuclear fusion
occurring in its core. If Jupiter had been massive enough to become
a star, our solar system would have been a binary system, with two
Suns.
49. Optical telescopes use the properties of lightƒƒeither refraction or
reflectionƒƒto gather and concentrate light. Nonoptical telescopes
use light-sensitive devices (rather than the human eye), such us
photographic films, solid-state photoelectric chips, or
photomultiplier tubes. These light-sensitive devices are more
sensitive than the eye, and they can give a quantitative measure of
the amount of light coming in.
50. A blackbody radiator absorbs all of the radiation that strikes it,
and reflects none. This is true of the Sun. Also, the Sun emits
radiation in a spectrum that is almost identical to the spectrum of
radiation emitted by a blackbody radiator heated to 5800K, the
average temperature of the visible layer of the Sun.
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