Astronomy A Beginners Guide to the Universe 7th Edition By Chaisson – Test Bank

Complete Test Bank With Answers

 

 

Sample Questions Posted Below

 

Astronomy: A Beginner’s Guide to the Universe, 7e (Chaisson/McMillan)

Chapter 5   Earth and Its Moon: Our Cosmic Backyard

1) Our Earth is about four times larger than the Moon in diameter.

Answer:  TRUE

Diff: 1

Section Ref.:  5.1

2) Compared to Earth, the Moon lacks a hydrosphere, atmosphere, and a magnetosphere.

Answer:  TRUE

Diff: 2

Section Ref.:  5.1

3) The Earth’s hotter, inner core is liquid and its cooler, outer core is solid.

Answer:  FALSE

Diff: 2

Section Ref.:  5.1

4) On average, the Moon orbits Earth from a distance of about 30 Earth radii.

Answer:  FALSE

Diff: 2

Section Ref.:  5.1

5) Neap tides occur at first and third quarter phases of the Moon.

Answer:  TRUE

Diff: 1

Section Ref.:  5.2

6) The tidal pull of the Moon is an example of a differential force, as the near and far sides of the Earth do not experience the same gravitational pull of the Moon.

Answer:  TRUE

Diff: 1

Section Ref.:  5.2

7) The Moon keeps one side facing the Earth because it doesn’t rotate on its axis.

Answer:  FALSE

Diff: 2

Section Ref.:  5.2

8) The Earth and Moon always keep the same side towards each other.

Answer:  FALSE

Diff: 2

Section Ref.:  5.2

9) Spring tides occur only at new Moon, when the Moon and Sun pull together.

Answer:  FALSE

Diff: 2

Section Ref.:  5.2

10) In most places on the seacoast, there are two high and two low tides a day.

Answer:  TRUE

Diff: 2

Section Ref.:  5.2

11) Due to its larger mass, the Sun’s gravitational effect on Earth’s tides is greater than the Moon’s.

Answer:  FALSE

Diff: 2

Section Ref.:  5.2

12) Greenhouse gases in our atmosphere trap just enough heat to keep the Earth’s oceans liquid.

Answer:  TRUE

Diff: 1

Section Ref.:  5.3

13) Weather occurs in the troposphere.

Answer:  TRUE

Diff: 1

Section Ref.:  5.3

14) The continuing rise of carbon dioxide concentration in our troposphere is leading to worldwide cooling as dry ice forms at the poles.

Answer:  FALSE

Diff: 1

Section Ref.:  5.3

15) The ozone layer lies above the troposphere and below the mesosphere.

Answer:  TRUE

Diff: 2

Section Ref.:  5.3

16) The three most abundant gases in our atmosphere are nitrogen, oxygen, and argon.

Answer:  TRUE

Diff: 2

Section Ref.:  5.3

17) The Moon’s surface gravity is only half the Earth’s.

Answer:  FALSE

Diff: 2

Section Ref.:  5.3, 5.1

18) The Moon’s lower density indicates it has a smaller concentration of iron in its core, as does the absence of a lunar magnetic field.

Answer:  TRUE

Diff: 1

Section Ref.:  5.4

19) The Earth’s inner core is about the same temperature as the surface of the Sun.

Answer:  TRUE

Diff: 2

Section Ref.:  5.4

20) Seismic P-waves can travel through both solid and liquid materials.

Answer:  TRUE

Diff: 2

Section Ref.:  5.4

21) Seismic S-waves can travel through Earth’s liquid outer core.

Answer:  FALSE

Diff: 2

Section Ref.:  5.4

22) One source of the energy for volcanism and plate tectonics is radioactivity in the Earth’s interior.

Answer:  TRUE

Diff: 2

Section Ref.:  5.4, 5.5

23) A seismograph could register P but not S waves from an epicenter on the opposite side of the Earth.

Answer:  TRUE

Diff: 2

Section Ref.:  5.4

24) Samples of the Earth’s molten outer core come directly through the mantle, pour out of volcanoes, and can be studied in labs.

Answer:  FALSE

Diff: 2

Section Ref.:  5.4

25) Seismic P-waves can be detected worldwide from any strong epicenter.

Answer:  TRUE

Diff: 3

Section Ref.:  5.4

26) There is no evidence for plate tectonics on the Moon today.

Answer:  TRUE

Diff: 1

Section Ref.:  5.5

27) In the past, most of the landmass on Earth was concentrated in a single, large continent.

Answer:  TRUE

Diff: 1

Section Ref.:  5.5

28) When plates collide, they fuse together and come to rest.

Answer:  FALSE

Diff: 2

Section Ref.:  5.5

29) Early telescopic observers thought the lunar mare were seas of water; today we know they are not liquid water but molten basalt, long ago frozen out.

Answer:  TRUE

Diff: 2

Section Ref.:  5.5

30) Most lunar craters are volcanic in origin.

Answer:  FALSE

Diff: 2

Section Ref.:  5.6

31) The Moon and the crustal rocks of Earth are similar in density.

Answer:  TRUE

Diff: 2

Section Ref.:  5.6

32) The Van Allen belts are cloud layers in the jet streams of the stratosphere, similar to the belts that Galileo saw on Jupiter.

Answer:  FALSE

Diff: 2

Section Ref.:  5.7

33) The lunar mare are younger than any of the craters that sit in them.

Answer:  FALSE

Diff: 2

Section Ref.:  5.8

34) The lunar highlands appear brighter than the mare, because these highlands are due to meteor impact that completely avoided the mare.

Answer:  FALSE

Diff: 2

Section Ref.:  5.8

35) The lunar mare radioactively date back to 4.6 billion years, at the origin of the Moon, hence their dark color due to this aging.

Answer:  FALSE

Diff: 2

Section Ref.:  5.8

36) The crust on the near side of the Moon is on average thinner than the crust on the far side, due to our tidal pull on the Moon.

Answer:  TRUE

Diff: 2

Section Ref.:  5.8

37) Today most scientists favor the capture theory of the Moon’s origin, since it would explain why the Moon still orbits in the ecliptic plane, as do other planets.

Answer:  FALSE

Diff: 2

Section Ref.:  5.8

38) Which of the following layers of the Earth is unique among the terrestrial planets?

A) hydrosphere

B) ionosphere

C) mantle

D) crust

E) core

Answer:  A

Diff: 1

Section Ref.:  5.1

39) At what phase would you expect to find extremely high and low tides?

A) new moon

B) first and third quarter

C) full moon

D) both new and full moons

E) Moon phases do not impact the tides.

Answer:  D

Diff: 2

Section Ref.:  5.2

40) What is true of spring tides?

A) The third quarter moon would be high overhead at dawn.

B) The difference between low and high tides would be greatest.

C) There would be one high and one low tide each day.

D) The Moon’s phase will be first quarter.

E) The difference between low and high tides would be smallest.

Answer:  B

Diff: 2

Section Ref.:  5.2

41) At what phase are the tides least noticeable?

A) new moon

B) full moon

C) third quarter

D) waxing crescent

E) waning gibbous

Answer:  C

Diff: 2

Section Ref.:  5.2

42) The Moon’s near side always faces Earth due to

A) the Sun’s gravity.

B) Earth’s magnetic field.

C) Earth’s tidal force.

D) conservation of angular momentum in the solar nebula.

E) the solar wind.

Answer:  C

Diff: 2

Section Ref.:  5.2

43) The smallest high tides occur when the Moon phase is

A) first or third quarter.

B) full.

C) new.

D) waxing or waning crescent.

E) waxing or waning gibbous.

Answer:  A

Diff: 2

Section Ref.:  5.2

44) What is true of the Moon’s orbital and rotational periods?

A) The rotational period is longer.

B) The orbital period is longer.

C) The rotational period varies with the Moon’s phase.

D) They are equal.

E) The orbital period is greatest at full moon.

Answer:  D

Diff: 3

Section Ref.:  5.2

45) Almost all of our atmospheric gases lie in the

A) ionosphere.

B) stratosphere.

C) troposphere.

D) ozone layer.

E) mesosphere.

Answer:  C

Diff: 1

Section Ref.:  5.3

46) The critical part of the atmosphere for protecting life on the ground from excessive ultraviolet radiation is the

A) hydrosphere.

B) troposphere.

C) ozone layer.

D) stratosphere.

E) ionosphere.

Answer:  C

Diff: 1

Section Ref.:  5.3

47) In what part of our atmosphere do we live?

A) troposphere

B) stratosphere

C) mesosphere

D) ionosphere

E) exosphere

Answer:  A

Diff: 1

Section Ref.:  5.3

48) Which of these gases is least abundant in our atmosphere?

A) hydrogen

B) carbon dioxide

C) argon

D) nitrogen

E) oxygen

Answer:  A

Diff: 2

Section Ref.:  5.3

49) Without the greenhouse effect operating in our atmosphere,

A) we would not have to worry about any warming problems in the future.

B) Earth would have an average temperature of -23 degrees Celsius.

C) the ice in the polar regions would have melted long ago.

D) the ozone layer would not be weakening.

E) the Earth would have become much more like Venus long ago.

Answer:  B

Diff: 2

Section Ref.:  5.3

50) What is the average molecular speed of hydrogen (mass = 1) on Earth (temperature = 300 K)?

A) 4.71 km/s

B) 2.72 m/s

C) 4.71 m/s

D) 2.72 km/s

E) None of the above

Answer:  D

Diff: 3

Section Ref.:  More Prec. 5.1

51) The major presence of water detected on the Moon is in

A) the mare.

B) the floors of deep craters in the polar regions, as ice deposits that never thaw.

C) the flows of mud seen on the walls of some craters.

D) the puffs of steam seen coming from some still active lunar volcanoes.

E) faint clouds of ice in the thin lunar atmosphere.

Answer:  B

Diff: 2

Section Ref.:  5.3

52) After the Lunar Reconnaissance Orbiter (LRO) crashed into the moon, its sister spacecraft LCROSS detected an amount of water in the ejecta

A) comparable to soggy ground on Earth.

B) comparable to fertile soil on Earth.

C) comparable to dried-up lake beds on Earth.

D) less than is contained in desert sand on Earth.

E) Actually, no water was detected at all.

Answer:  D

Diff: 2

Section Ref.:  5.3

53) The average rate of erosion on the Moon is far less than on Earth because

A) the crust of the Moon is much denser than the Earth’s crust.

B) the Moon is much younger than the Earth.

C) the Moon lacks wind, water, and an atmosphere.

D) the Moon’s magnetic field protects it from the solar wind better than ours does.

E) the Moon’s mare long ago dried up, so there is no more wave erosion there.

Answer:  C

Diff: 2

Section Ref.:  5.3

54) We determine the structure of the Earth’s core using

A) deep mine shafts.

B) satellite imaging.

C) radar and sonar.

D) seismic wave data.

E) magnetic resonance imaging.

Answer:  D

Diff: 1

Section Ref.:  5.4

55) The atmospheric gases primarily responsible for our greenhouse effect are

A) carbon monoxide and methane.

B) hydrogen and helium.

C) oxygen and carbon dioxide.

D) argon and water vapor.

E) water vapor and carbon dioxide.

Answer:  E

Diff: 1

Section Ref.:  5.4

56) In noting that the Earth is “differentiated,” we mean that

A) the density increases as you descend downward toward the core.

B) the Earth is very different than any other planet we study.

C) the Earth’s magnetic field varies at different locations on the globe.

D) the density of oceanic basalt is less than that of granite on the mountain tops.

E) the radioactive heating in the core is increasing with time.

Answer:  A

Diff: 1

Section Ref.:  5.4

57) Seismic waves are most useful for mapping

A) the surface of Venus with Magellan.

B) the surface of Mars with Global Surveyor.

C) the Earth’s core and mantle.

D) the density of the hydrosphere.

E) the depths of the oceans.

Answer:  C

Diff: 2

Section Ref.:  5.4

58) Which statement about seismic waves is true?

A) Only S waves can travel through liquid.

B) P waves travel faster, and thus arrive sooner than do the S waves.

C) In the shadow zones, neither type is observed.

D) S waves can travel though the outer core, but P waves cannot.

E) On the far side of the Earth, only the S waves on the surface can be detected.

Answer:  B

Diff: 3

Section Ref.:  5.4

59) Which of these is not a result of plate tectonics?

A) the Grand Canyon

B) the Andes

C) the Mid-Atlantic Rift

D) the San Andreas Fault

E) the Philippine Trench

Answer:  A

Diff: 2

Section Ref.:  5.5

60) Today, an average lunar moonquake releases about as much energy as

A) an atomic bomb.

B) a firecracker.

C) the Mount St. Helens eruption.

D) a major U.S. city uses in 1 year.

E) the most powerful earthquake ever recorded.

Answer:  B

Diff: 2

Section Ref.:  5.5

61) The far side of the Moon was first mapped

A) by Galileo in 1610 with his first telescope.

B) by the Apollo astronauts on the first orbit of the Moon with Apollo 8.

C) by early Russian spacecraft.

D) by NASA with its Lunar Orbiters in the 1960s.

E) by William Herschel with his large reflectors in the early 1800s.

Answer:  C

Diff: 2

Section Ref.:  5.6

62) The lunar mare are found

A) uniformly all over the Moon.

B) mainly on the near side.

C) mainly on the far side.

D) only in the dark areas of the lunar poles, where water is not boiled away.

E) only as layered rocks, since the original water was lost long ago.

Answer:  B

Diff: 2

Section Ref.:  5.6

63) Which of these age ranges best describes the lunar maria?

A) 8.6 – 6.0 billion years

B) 3.9 – 3.2 billion years

C) 2.5 – 1.0 billion years

D) 100 – 65 million years

E) a few million years to present lava flows seen erupting

Answer:  B

Diff: 2

Section Ref.:  5.6

64) The rate of cratering in the lunar highlands shows us that

A) they must be younger than the older, darker mare.

B) they range from 4.6 – 4.4 billion years old, on average.

C) the largest impacts are the youngest, such as Copernicus and Tycho.

D) the oldest rocks are at least as old as the mare, but some craters are much younger.

E) most of the asteroids must have hit the Moon, not the Earth.

Answer:  B

Diff: 2

Section Ref.:  5.6

65) What is true of the lunar highlands?

A) They are found on the Moon’s northern hemisphere.

B) They are less heavily cratered than the mare.

C) They are the darker regions of the Moon seen with the naked eye.

D) They are younger than the darker mare.

E) They are the oldest part of the lunar surface.

Answer:  E

Diff: 3

Section Ref.:  5.6

66) The presence of a magnetic field is a good indication that

A) the Earth’s interior is similar to Mercury’s, as both have fields.

B) a huge iron meteorite lies somewhere high up in the mantle, not in the core.

C) the Earth has a liquid metal outer core, spinning rapidly as it rotates.

D) the Earth’s interior must be completely molten to the center.

E) the Earth’s interior has had time to solidify, with a rigid bar magnet created.

Answer:  C

Diff: 1

Section Ref.:  5.7

67) When strong solar winds are displaced poleward by our magnetic fields, we get

A) the Van Allen radiation belts.

B) intense auroral displays.

C) sunspots.

D) hurricanes in the tropics.

E) droughts and dust bowls in the American West.

Answer:  B

Diff: 1

Section Ref.:  5.7

68) The region in which charged particles are trapped by our magnetic fields is the

A) ionosphere.

B) ozone layers.

C) exosphere.

D) Van Allen radiation belt.

E) Aurora.

Answer:  D

Diff: 2

Section Ref.:  5.7

69) Earth’s magnetic field

A) prevents charged particles in the solar wind from reaching the surface.

B) is a remnant of the solar nebula’s magnetic field.

C) is weakening the Van Allen radiation belts.

D) is the force behind plate tectonics.

E) lines intersect the atmosphere at the equator.

Answer:  A

Diff: 2

Section Ref.:  5.7

70) Which statement about our core is FALSE?

A) It generates a stable and permanent magnetic field much as a regular bar magnet.

B) Its magnetic field generates the protective Van Allen radiation Belts.

C) It must be rich in both iron and nickel.

D) The seismic data indicates the outer portion is liquid, the inner part solid.

E) It is almost as hot as the Sun’s glowing surface, the photosphere.

Answer:  A

Diff: 3

Section Ref.:  5.7

71) Which of these theories seems to best explain the Moon’s origin?

A) Impact Theory

B) Capture Theory

C) Coformation Theory

D) Fission Theory

E) Fusion Theory

Answer:  A

Diff: 1

Section Ref.:  5.8

72) The bulk density of the Moon is ________ than that of the Earth it orbits.

Answer:  less (about 60%)

Diff: 1

Section Ref.:  5.1

73) The ________ tides occur when there is little tidal variation, near first and third quarter moons.

Answer:  neap

Diff: 1

Section Ref.:  5.2

74) The ________ tides have a large change from high to low, near new and full moons.

Answer:  spring

Diff: 1

Section Ref.:  5.2

75) The spring tide can occur at either ________ or ________ phases of the Moon.

Answer:  new; full

Diff: 1

Section Ref.:  5.2

76) The neap tide can occur at the ________ or ________ phases of the Moon.

Answer:  first; third quarter

Diff: 1

Section Ref.:  5.2

77) The Moon’s spin-orbit resonance shows it is ________ with the Earth.

Answer:  tidally locked

Diff: 1

Section Ref.:  5.2

78) The Sun reinforces the Moon’s tidal pull during ________ tides.

Answer:  spring

Diff: 1

Section Ref.:  5.2

79) The tidal pull of the Sun largely cancels that of the Moon at the ________ phases.

Answer:  quarter

Diff: 1

Section Ref.:  5.2

80) Plate ________ is the process by which convection within the mantle reforms the crust above it.

Answer:  tectonics

Diff: 1

Section Ref.:  5.5

81) The ________ has the largest gravitational pull on Earth.

Answer:  Sun

Diff: 1

Section Ref.:  5.2

82) The difference in the Moon’s gravitational force on the near and far sides of the Earth produces a ________.

Answer:  tidal bulge

Diff: 2

Section Ref.:  5.2

83) The greenhouse effect always results in a ________ surface temperature.

Answer:  higher or hotter

Diff: 1

Section Ref.:  5.3

84) The ozone layer blocks much of the Sun’s ________ radiation.

Answer:  ultraviolet

Diff: 1

Section Ref.:  5.3

85) The most abundant gas in the Earth’s atmosphere is ________.

Answer:  nitrogen

Diff: 1

Section Ref.:  5.3

86) The oxygen in our atmosphere is produced by ________.

Answer:  life processes

Diff: 1

Section Ref.:  5.3

87) The ________ in our atmosphere is the result of photosynthesis by plants.

Answer:  oxygen

Diff: 1

Section Ref.:  5.3

88) ________ radiation is trapped close to our surface by the greenhouse effect.

Answer:  Infrared (or heat)

Diff: 1

Section Ref.:  5.3

89) The Moon lacks an atmosphere because its surface gravity is only ________ the Earth’s.

Answer:  one-sixth

Diff: 2

Section Ref.:  5.3

90) The water that has been detected on the Moon lies at its ________.

Answer:  poles

Diff: 2

Section Ref.:  5.3

91) Weather always occurs in the lowest layer of the atmosphere, the ________.

Answer:  troposphere

Diff: 2

Section Ref.:  5.3

92) Our molten core is believed to consist primarily of the element ________.

Answer:  iron

Diff: 1

Section Ref.:  5.4

93) To map the Earth’s interior, we rely on ________ waves created by earthquakes.

Answer:  seismic

Diff: 1

Section Ref.:  5.4

94) The most important greenhouse effect gas in our atmosphere is ________.

Answer:  carbon dioxide

Diff: 1

Section Ref.:  5.4

95) Because the interior of the Earth is ________, the crust is much less dense than the core.

Answer:  differentiated (or molten)

Diff: 2

Section Ref.:  5.4

96) The ________ seismic waves can pass through both solid and liquid portions of the Earth’s interior, and be detected on the other side of the globe.

Answer:  P

Diff: 2

Section Ref.:  5.4

97) For differentiation to have occurred, the Earth’s interior must have been ________.

Answer:  molten

Diff: 2

Section Ref.:  5.4

98) ________ waves cannot travel through the Earth’s liquid outer core.

Answer:  S

Diff: 2

Section Ref.:  5.4

99) A hot, molten body of different materials will become ________.

Answer:  differentiated

Diff: 2

Section Ref.:  5.4

100) ________ is responsible for heating the Earth’s interior today.

Answer:  Radioactive decay

Diff: 2

Section Ref.:  5.4

101) The oldest rocks found on the Earth’s surface date back about ________ billion years.

Answer:  four

Diff: 1

Section Ref.:  5.8

102) The ________ in the oceans arise where two advancing plates meet and one is pushed beneath the other, a process called subduction.

Answer:  trenches

Diff: 2

Section Ref.:  5.5

103) Dominating the lunar ________, craters are the result of asteroid and comet impacts.

Answer:  highlands

Diff: 1

Section Ref.:  5.6

104) The dominant dark features on the near side of the Moon are the ________.

Answer:  mare

Diff: 1

Section Ref.:  5.6

105) The age dating of the solar system is done by radioactive dating of ________.

Answer:  meteorites

Diff: 1

Section Ref.:  5.6

106) The mare are really seas of long since hardened ________, a dark volcanic rock that also makes up the ocean basins of Earth.

Answer:  basalt

Diff: 2

Section Ref.:  5.6

107) When strong solar wind storms are diverted poleward by our magnetic fields, we often observe ________ in the ionosphere.

Answer:  aurorae

Diff: 1

Section Ref.:  5.7

108) The ________ are two layers of charged particles trapped by our magnetic fields.

Answer:  Van Allen radiation belts

Diff: 1

Section Ref.:  5.7

109) In order for the dynamo effect to generate a magnetic field, Earth’s outer core must be rapidly spinning, molten, and made of ________.

Answer:  conducting materials

Diff: 3

Section Ref.:  5.7

110) The coformation hypothesis for the origin of the Moon is difficult to reconcile with the dissimilar ________ and ________ of the Earth and Moon.

Answer:  density; composition.

Diff: 1

Section Ref.:  5.8

111) The ________ hypothesis is now the most popular to explain the Moon’s origin.

Answer:  impact

Diff: 1

Section Ref.:  5.8

112) In general, the ________ lunar craters sit atop the mare.

Answer:  youngest

Diff: 2

Section Ref.:  5.8

113) The Moon’s composition is similar to Earth’s ________.

Answer:  mantle.

Diff: 3

Section Ref.:  5.8

114) List the six main regions of the Earth, in order, starting from the center.

Answer:  core, mantle, crust, hydrosphere, atmosphere, magnetosphere

Diff: 3

Section Ref.:  5.1

115) When do spring tides occur? How much tidal variation is noted?

Answer:  When Earth, Moon, and Sun are aligned, at new and full phases. The difference between high and low tides is large.

Diff: 2

Section Ref.:  5.2

116) When and why do neap tides occur? How much tidal variation is noted?

Answer:  At first and third quarter phase, the Sun cancels out the Moon’s tidal pull to some degree, and the tidal variation is small.

Diff: 2

Section Ref.:  5.2

117) What is meant by tidal locking?

Answer:  The gravitational force of the Earth on the Moon has slowed the Moon’s rotation so that it rotates (spins) once during every orbit. One side always faces the Earth.

Diff: 3

Section Ref.:  5.2

118) What are the short- and long-term effects of the Moon’s tides on our rotation?

Answer:  The Moon slows down our rotation slightly, with precession being the long-term effect of this tidal distortion.

Diff: 3

Section Ref.:  5.2

119) Why does the Moon lack an atmosphere?

Answer:  Its atmosphere escaped into space due to the low surface gravity of the Moon.

Diff: 2

Section Ref.:  5.3

120) Name the layers of the Earth’s atmosphere, going up from the surface.

Answer:  troposphere, stratosphere, mesosphere, ionosphere

Diff: 3

Section Ref.:  5.3

121) Why does the Earth’s atmosphere contain much more nitrogen than hydrogen?

Answer:  Heavier nitrogen can be retained by our gravity, whereas lighter hydrogen leaks away into space, because its average molecular speed at the Earth’s temperature exceeds the Earth’s escape velocity.

Diff: 3

Section Ref.:  More Prec. 5.1

122) What does it mean when we say the Earth’s interior is differentiated?

Answer:  In a molten state, the denser materials sank to our core, and the lighter material rose to form our crust.

Diff: 1

Section Ref.:  5.4

123) What were the two primary courses of heating that let the Earth differentiate?

Answer:  Impacts of interplanetary debris and radioactive decay.

Diff: 2

Section Ref.:  5.4

124) Which side of the Moon has the thicker crust? Why?

Answer:  The far side, because our tides pulled the molten core toward us, making the Earth-side crust thinner.

Diff: 2

Section Ref.:  5.4

125) Where is the newest material in the Earth’s crust found?

Answer:  At the mid-ocean ridges, where plate tectonics constantly extrudes new lava.

Diff: 2

Section Ref.:  5.5

126) Note at least three surface features that are driven by plate tectonics.

Answer:  Rift valleys, trenches, mountain ranges, volcanic chains, faults, midocean ridges

Diff: 1

Section Ref.:  5.5

127) What surface region of the Moon is oldest? How do we know this?

Answer:  The highlands are older than the maria, as evidenced both by the higher degree of cratering and the actual radioactive dating of Apollo samples.

Diff: 1

Section Ref.:  5.6

128) List the two major regions of the near side of the Moon, as seen with the naked eye.

Answer:  The darker maria and the brighter highlands

Diff: 1

Section Ref.:  5.6

129) What is the primary source of erosion on the Moon today?

Answer:  Meteorite and micrometeorite bombardment of the surface slowly reduces and alters the features, creating a thick layer of dust.

Diff: 3

Section Ref.:  5.6

130) Name two consequences of the Earth’s magnetic field detected from space.

Answer:  The Van Allen radiation belts lie around our equator, and the tail of charged particles much like a comet’s tail extending past the Moon.

Diff: 3

Section Ref.:  5.7

131) Name two observable consequences of the Earth’s tidal pull on the Moon.

Answer:  The Moon is tidally locked by our tides, with the same heavier side always pointed toward us; the tides also caused the dark mare to flow out on our side chiefly.

Diff: 2

Section Ref.:  5.8

132) Of the six layers of Earth, which is unique among the planets? Why?

Answer:  The hydrosphere, since liquid water is found on the surface in abundance here only.

Diff: 2

Section Ref.:  5.1

133) Why does the Moon play a larger role in tides than the Sun?

Answer:  The Sun is much more massive, and has a greater gravitational pull, but the Moon is much closer, and differentially pulls more on the side of Earth it faces.

Diff: 2

Section Ref.:  5.2

134) Contrast spring and neap tides.

Answer:  At spring tides, the Sun and Moon act in concert, making for large tidal variation. At neap tides, the Sun lies 90 degrees from the Moon at quarter phases, and largely cancels out the tidal pull of the Moon.

Diff: 2

Section Ref.:  5.2

135) Contrast S and P waves in terms of speed and transmission through the interior.

Answer:  P waves travel faster, and can move through the molten outer core, while slower S waves are not able to pass through a fluid such as the core.

Diff: 2

Section Ref.:  5.4

136) Why are plate tectonics not as important a factor on the Moon as they are on Earth?

Answer:  The Moon no longer has a molten core, and as it chilled faster than did the larger Earth, the Moon has a thicker crust. The Earth’s thin crust is constantly being broken by the conveyor belt of magma pushing upward through our mantle.

Diff: 3

Section Ref.:  5.4, 5.5

137) How do earthquakes allow us to model the structure of Earth’s core?

Answer:  Examining the different seismic waves we find P and S waves are not recorded by all over the planet. There is a blind spot for S waves on the side of Earth opposite the earthquake, and there is a shadow zone part way around the surface from the earthquake. Since we know S waves cannot travel through liquid and P waves can, we conclude the Earth’s core is liquid. Since P waves bend when they enter the liquid core, but some travel straight through, it implies there is a solid center to the liquid outer core.

Diff: 3

Section Ref.:  5.4

138) Name the three principal divisions of the structure of the Earth’s interior and the chemical composition of each.

Answer:  The core is made of molten iron and nickel, the mantle of silicates, and the crust of still less dense silicates.

Diff: 3

Section Ref.:  5.4

139) According to the reanalysis of the Apollo seismic data in 2011, what is the structure of the lunar interior?

Answer:  The central core is about 330 km in radius. The innermost 240 km is solid; the rest, as well as the innermost 150 km of the surrounding inner mantle, is liquid. The rest of the inner mantle, 250 km worth, is semi-solid; the outer mantle is about 900 km thick and is solid. The solid crust varies in thickness from 60 to 150 km.

Diff: 2

Section Ref.:  5.5

140) Which two continents are the most obvious pieces in the continental jigsaw puzzle of plate tectonics? Why?

Answer:  South America and Africa were split by the mid-Atlantic rift, and have spread apart in the last 70 million years.

Diff: 2

Section Ref.:  5.5

141) Where is the most obvious example of a mountain chain built by continental collision in plate tectonics? Which plates are involved in this head-on collision?

Answer:  The Himalaya Mountains are the result of the uplifting as the Indian subcontinent has rammed into Asia in the last 30 million years.

Diff: 2

Section Ref.:  5.5

142) Which plates are causing the formation of the Andes mountains in western South America? Describe their motions.

Answer:  The Nazca plate and South American Plate are moving toward each other, causing the Andes mountains.

Diff: 3

Section Ref.:  5.5

143) Why are Moon rocks older than Earth rocks, if the impact theory has the Moon being made by another body striking the newly formed Earth?

Answer:  The Earth’s surface is constantly being reformed by plate tectonics and atmospheric erosion processes, while the Moon is no longer geologically active.

Diff: 3

Section Ref.:  5.5

144) Why is the Moon heavily cratered but Earth is not?

Answer:  The Moon lacks an atmosphere which means it has no weather. It also lacks a molten interior which means it has no plate tectonics. On the Moon the major form of erosion is meteorite bombardment, which is a very slow process. On Earth, wind and rain cause weathering (rapid erosion) of crater features. Plate tectonics is constantly changing the surface of the Earth, creating new crust and recycling old.

Diff: 3

Section Ref.:  5.5, 5.6

145) What features are conspicuously absent from the far side of the Moon? Why?

Answer:  The mare are found chiefly on the side facing Earth, since our tides have pulled the formerly molten lunar core closer to us, making the crust thinner on our side.

Diff: 2

Section Ref.:  5.6

146) Explain how crater counts allow us to estimate the ages of surfaces throughout the solar system.

Answer:  Craters are the rule…everybody was a target in the early days of accretion. The longer the surface has sat without internal deformation, the more impacts have cratered the surface. If craters are absent, it is because other processes, such as lava flows or erosion, have replaced the older cratering.

Diff: 2

Section Ref.:  5.6

147) What is the primary source of erosion on the Moon? Why does change there take so long?

Answer:  A constant fall of meteoroids from space pelts the moon, pulverizing the surface with tiny craters. But really big impacts are rare, and these microscopic changes take a long time to show up as seen from Earth. Our erosive agents like wind, water, and ice can make much more dramatic changes in short periods of time, such as floods, sandstorms, glaciers, etc.

Diff: 3

Section Ref.:  5.6

148) Relate our magnetic field to the aurorae.

Answer:  The magnetic field’s Van Allen radiation belts deflect the charged particles away from our equator toward the poles, where the charged particles spiral down the magnetic field lines and hit the ionosphere to create the colorful ionized patterns.

Diff: 2

Section Ref.:  5.7

149) Why is the impact theory now preferred as an explanation for the Moon’s origin?

Answer:  The capture theory is unlikely for a body as big as the Moon, while the coformation theory would have the Moon orbit our equator as it condensed. The impacting body would be of different composition than the Earth, and the heat of impact would drive off the lighter materials, as noted for the Moon’s crust. The body would also have been moving in the ecliptic plane before impact, and the Moon still orbits close to the ecliptic even now.

Diff: 3

Section Ref.:  5.8

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