1. The tendency of cool gas to sink and warm gas to rise is called:
a) Differentiation.
b) Differential rotation.
c) Convection.
d) A magnetic dynamo.
e) The Greenhouse Effect.

2. In the Greenhouse Effect, what type of radiation is trapped by the Earth's atmosphere?
a) Ultraviolet.
b) Infrared.
c) Visible.
d) Radio.
e) The solar wind.

3. Why is the sky blue?
a) The light from the sun is blueshifted.
b) Blue light is too low energy to get through the Earth's atmosphere.
c) Particles from the solar wind spiral along the Earth's magnetic field lines and produce blue light.
d) The Earth's atmosphere is warm, and so emits blue light.
e) Blue light is scattered more than red light.

4. Which planets have observed magnetic fields?
a) The Earth, Mars, Jupiter, Saturn.
b) The Earth, Mercury, Jupiter, Saturn, Uranus, Neptune.
c) The Earth, Mars, Venus, Jupiter, and Saturn.
d) The Earth, Venus, Mars, Mercury.
e) The Earth, Jupiter, Saturn.

5. The magnetic field of the Earth is caused by:
a) The solid inner core of the Earth, which is a strong magnet.
b) The solar wind.
c) The rotation of the Earth creating an electric current in the liquid outer core of the Earth.
d) The rotation of the Earth creating an electric current in the semi-liquid upper layer of the Earth's mantle.
e) Plate tectonics.

6. A seismic S-wave:
a) travels through liquids, but not solids.
b) travels through solids, but not liquids.
c) travels through both liquids and solids.
d) travels only on the surfaces of planets, not through the interiors.
e) will travel straight through the Earth, to the point directly opposite.

7. Which of the following molecules contributes significantly to the greenhouse effect?
a) Nitrogen.
b) Oxygen.
c) Carbon dioxide.
d) Ozone.
e) Hydrogen.

8. Which of the following objects has the strongest magnetic field?
a) Mercury.
b) The Moon.
c) Mars.
d) Venus.
e) The Earth.

9. Which of the following are called `Greenhouse Gases', since they contribute the most to the Greenhouse Effect?
a) CO₂, H₂O, and methane.
b) H₂.
c) Ozone.
d) O₂ and N₂.
e) Argon.

10. Which of the following types of seismic waves travel through the liquid outer core of the Earth?
a) P waves only.
b) S waves only.
c) L waves only.
d) P and S waves only.
e) S and L waves only.

11. From the surface of the Earth outwards, which is the correct order of the following layers of the Earth's atmosphere?
a) the ozone layer (closest to Earth); the layer that dominates in the Greenhouse Effect; the ionosphere.
b) the ionosphere (closest to Earth); the ozone layer; the layer that dominates in the Greenhouse Effect.
c) The layer that dominates in the Greenhouse Effect (closest to Earth); the ionosphere; the ozone layer.
d) the ozone layer (closest to Earth); the ionosphere; the layer that dominates in the Greenhouse Effect.
e) The layer that dominates in the Greenhouse Effect (closest to Earth); the ozone layer; the ionosphere.

12. Aurora are caused by:
a) scattering of sunlight by the Earth's atmosphere.
b) solar wind particles spiraling along the Earth's magnetic field lines and exciting molecules in the Earth's atmosphere.
c) the absorption of ultraviolet light from the Sun by the ozone layer.
d) long-wavelength radio waves being reflected by the ionosphere.
e) convection in the Earth's atmosphere.

13. Why does the Sun have a reddish/orangish color at sunset?
a) Sunlight is redshifted at sunset.
b) Solar wind particles interact with the Earth's atmosphere, producing red photons.
c) The Earth's atmosphere is cooler at sunset, and so makes the Sun appear cooler (i.e., redder).
d) blue sunlight is scattered more than red sunlight, and the path length for sunlight is longer at sunset.
e) The Sun is cooler at sunset.

14. Which terrestrial planets have global magnetic fields?
a) Just the Earth.
b) The Earth and Mercury.
c) The Earth, Mars, and Venus.
d) The Earth and Mars.
e) The Earth and Venus.

15. The main constituent of the atmospheres of both Mars and Venus is:
a) CO₂.
b) O₂.
c) H₂O vapor.
d) H₂.
e) sodium and helium.

16. After the Earth, which of the following objects has the strongest magnetic field?
a) Mercury.
b) Venus.
c) Mars.
d) The Moon.
e) None of these objects has a global magnetic field.

17. The ozone layer is responsible for blocking which type of radiation from reaching the Earth's surface?
a) X-rays.
b) ultraviolet light.
c) visible light.
d) infrared radiation.
e) radio waves.

18. What evidence do we have that the Earth has a liquid outer core?
a) The Earth has a strong magnetic field.
b) P-waves but not S-waves travel through it.
c) S-waves but not P-waves travel through it.
d) S-waves and P-waves travel through it, but not L-waves.
e) Both a) and b) above.

19. The Greenhouse Effect is caused by:
a) X-rays from the Sun being trapped by the ozone layer.
b) Infrared light from the Sun being trapped by the ionosphere.
c) Infrared light from the Earth being trapped by the Earth's lower atmosphere.
d) Radio waves being absorbed and re-emitted by the Earth's atmosphere.
e) Ultraviolet light from the Sun being absorbed by the ozone layer.

20. The Van Allen Belts are:
a) Moving charged particles in the outer core of the Earth.
b) The asteroid belts.
c) Swirling patterns in the Earth's atmosphere, due to convection and the rotation of the Earth.
d) Regions surrounding the Earth where charged particles from the Sun are trapped by the Earth's magnetic field.
e) The upper part of the mantle of the Earth, which is partially molten.

21. The Coriolis Force (Coriolis Effect) is:
a) a consequence of Newton's Laws applied to a rotating frame of reference.
b) the deflection of a moving charged particle by a magnetic field.
c) the magnetic field produced by a moving charged particle.
d) the fact that blue light is more likely to be scattered than red light.
e) the motion of the tectonic plates of Earth.

22. The time it takes for the heat from inside a planet to leak out (and the likelihood the planet has a liquid interior) is proportional to:
a) the radius of the planet.
b) the planetary radius³.
c) 1/radius.
d) 1/radius².
e) it does not depend upon the size of the planet.
e) b) or c) above, depending upon the distance from the Sun.

23. The Earth's magnetic field protects us from:
a) harmful ultraviolet photons from the Sun.
b) freezing to death: it helps keep us warm.
c) meteoroids: chunks of rocks from space that might hit the Earth.
d) the Greenhouse Effect.
e) the solar wind.

24. Convection is:
a) The scattering of blue light by the atmosphere.
b) The colorful displays produced when solar wind particles interact with the Earth's atmosphere.
c) the process by which warm air rises and cool air sinks.
d) the reflection of long-wavelength radio waves by the Earth's ionosphere.
e) the production of a bulge on a planet, due to differential gravitational forces.

25. Which of the following is/are mainly responsible for the absorption of infrared radiation in our atmosphere?
a) Ozone.
b) H₂ and He.
c) O₂ and N₂.
d) Argon.
e) CO₂, H₂O, and CH₄.

26. Long-wavelength radio waves (like those produced by AM radio stations) are:
a) reflected by the ionosphere.
b) strongly absorbed by the greenhouse gases.
c) responsible for convection in our atmosphere.
d) responsible for the Aurora Borealis.
e) absorbed by the ozone layer in the atmosphere.

27. What is the most likely reason that Mars does not have a strong global magnetic field, unlike Earth?
a) it is probably solid all the way through.
b) it does not have an ozone layer.
c) it is spinning much more slowly than the Earth.
d) both because it is probably solid throughout, and is spinning very slowly.
e) it is further from the Sun, so less affected by the solar wind.

28. Most of the X-rays from the Sun are stopped in which layer of our atmosphere?
a) the troposphere.
b) the mesosphere.
c) the stratosphere.
d) the ionosphere.
e) they are not stopped by our atmosphere; they reach the surface of the Earth unimpeded.

29. The `greenhouse gases', such as CO₂, H₂O, and CH₄, are the main molecules in our atmosphere responsible for absorbing:
a) UV light.
b) X-rays.
c) radio waves.
d) IR light.
e) visible light.

30. Seismic P waves:
a) Travel through both liquids and solids.
b) Only travel through solids.
c) Only travel through liquids.
d) Do not travel through either solids or liquids, just gases.
e) Only travel across the surface of the Earth; they do not penetrate the interior of the Earth.

31. What is the evidence that the outer core of the Earth is liquid?
a) Only P waves travel through it.
b) Only S waves travel through it.
c) Both P and S waves travel through it.
d) Drilling deep into the Earth shows that the outer core is liquid.
e) The Earth has an ionosphere.

32. The magnetic field of the Earth protects the Earth by preventing most of which of the following from hitting the surface of the Earth?
a) X-rays from the Sun.
b) UV from the Sun.
c) IR from the Sun.
d) the solar wind.
e) all of the above.

33. The global magnetic field of Venus is caused by:
a) convection in the asthenosphere (upper mantle).
b) the solid inner core of Venus, which acts like a giant magnet.
c) moving charged particles in the liquid outer core of Venus.
d) charged particles in the solar wind interacting with Venus's atmosphere.
e) Venus does not have a global magnetic field.

34. An extrasolar planet is:
a) either Earth, Mars, Venus, or Mercury.
b) either Jupiter, Saturn, Uranus, or Neptune.
c) a Kuiper belt object.
d) an asteroid.
e) a planet orbiting a star other than the Sun.

35. Planets have been discovered around a number of nearby stars. Which of the following is true about most of these planets?
a) They mostly have relatively large masses, similar to that of Neptune, Uranus, Jupiter, or Saturn or larger.
b) They are generally not visible in Hubble Space Telescope images.
c) Some of them are closer to their parent star than Mercury is to the Sun.
d) They were discovered by Doppler shift studies of the parent star.
e) All of the above.

36. Most of the extrasolar planets discovered so far have been found by:
a) direct observation of the planet as a distinct source on the source, separate from the star it is orbiting.
b) receiving a signal from an advanced civilization on the planet.
c) periodic redshifting and blueshifting of the light from the planet's star.
d) observation of a periodic dimming of the light from the planet's star due to transits by the planet.
e) Both c) and d) have been very successful.

37. What are the two main constituents of the Earth's atmosphere?
a) CO₂ and O₂.
b) H₂O and CH₄.
c) H₂ and He.
d) N₂ and O₂.
e) CO₂ and H₂O.

38. The very thin atmosphere on the Moon:
a) is left-over from the formation of the solar system.
b) is due to outgassing from the interior of the moon or planet.
c) is due to bombardment of the surface by the solar wind.
d) is caused by evaporation of polar icecaps.
e) was captured from the Earth.

39. Most of Saturn's atmosphere is probably:
a) due to outgassing from volcanoes on the surface of Saturn.
b) due to bombardment of the surface by the solar wind.
c) left-over from the formation of the solar system.
d) due to evaporation of ices on the surface of Saturn.
e) due to life forms on Saturn.

40. The main constituent of the atmosphere of which two objects is CO₂?
a) Triton and Titan.
b) Earth and Titan.
c) Titan and Mars.
d) Venus and Mars.
e) Venus and Titan.

41. Which terrestrial planet or moon has the highest atmospheric pressure at its surface?
a) Venus.
b) Mars.
c) Mercury.
d) Earth.
e) The Moon.

42. The main constituent of the atmospheres of which of the following two objects is nitrogen?
a) Venus and the Earth.
b) Mars and the Earth.
c) Venus and Mars.
d) The Earth and Titan.
e) Jupiter and Saturn.

43. The atmospheres of the Jovian planets were produced mainly by what process?
a) volcanoes.
b) comets hitting the planet and evaporating.
c) sublimination of ices on their surfaces.
d) gravitational capture of solar wind particles.
e) they are left-over from the formation of the solar system.

44. The moon with the thickest atmosphere is:
a) Io.
b) Europa.
c) Callisto.
d) Titan.
e) Triton.

45. Which of the following lists gives the correct order for the listed planets and moons, in terms of surface atmospheric pressure? (from biggest to smallest)
a) Earth, Venus, Mars, Titan, Mercury.
b) Venus, Earth, Mars, Titan, Mercury.
c) Venus, Mars, Titan, Earth, Mercury.
d) Venus, Earth, Mars, Mercury, Titan.
e) Venus, Titan, Earth, Mars, Mercury.

46. Which of the planets or moons listed below has an atmosphere with the same main component as that of Mars?
a) Mercury.
b) Venus.
c) Earth.
d) The Moon.
e) Titan.

47. The extrasolar planets discovered to date are:
a) mostly less massive than the Earth.
b) all orbiting their stars at distances larger than the orbit of Jupiter.
c) visible in pictures taken by the Voyager spacecraft.
d) mostly more massive than the Earth.
e) twelve in total.

48. The stratosphere is:
a) the lowest layer of the Earth's atmosphere.
b) the topmost layer of the Earth's atmosphere.
c) the layer of the Earth's atmosphere that contains the ozone layer.
d) mostly ionized.
e) is the liquid outer core of the Earth.

49. Which of the following planets is most likely to retain a thick atmosphere?
a) a planet with a hot atmosphere, a mass of 10 Earth masses, and a radius of 3 Earth radii.
b) a planet with a hot atmosphere, a mass of 2 Earth masses, and a radius of 3 Earth radii.
c) a planet with a cold atmosphere, a mass of 10 Earth masses, and a radius of 3 Earth radii.
d) a planet with a hot atmosphere, a mass of 10 Earth masses, and a radius of 1 Earth radii.
e) a planet with a cold atmosphere, a mass of 10 Earth masses, and a radius of 1 Earth radii.

50. The atmosphere of Venus is mostly:
a) CO₂ and N₂.
b) Hydrogen and helium.
c) N₂ and O₂.
d) CH₄ and N₂.
e) Potassium and sodium.

51. H₂ is the most common molecule in the atmosphere of:
a) Venus.
b) Earth.
c) The Jovian planets.
d) Mars.
e) Titan.

52. The atmosphere of Mercury is mainly due to:
a) volcanoes.
b) bombardment of its surface by the solar wind.
c) sublimination of ices.
d) left-over gases captured from the original interstellar cloud during the formation of Mercury.
e) evaporation of liquids.

53. N₂ is the most common molecule in the atmosphere of:
a) Venus.
b) Mercury.
c) The Jovian planets.
d) Mars.
e) Titan.

54. Most of the extrasolar planets discovered to date were found by:
a) imaging of the planet by the Voyager or Pioneer spacecraft.
b) imaging of the planet with the Hubble Telescope.
c) Doppler shift measurements of their star or by periodic dimming of the parent star due to a planetary transit.
d) amateur astronomers noticing new bright objects in the sky.
e) none have been found so far.

55. Which of the following objects has the largest atmospheric pressure on its surface?
a) Mars.
b) Triton.
c) Earth.
d) Venus.
e) Europa.

56. The primary constituent of the atmosphere of Jupiter is:
a) hydrogen.
b) CO₂.
c) O₂
d) N₂.
e) sodium.

57. Most of the extrasolar planets found so far have been found using which technique?
a) imaging with ultraviolet telescopes.
b) imaging with optical telescopes.
c) imaging with infrared telescopes.
d) imaging with X-ray telescopes.
e) measuring the alternating redshift/blueshift of a star, due to a planet orbiting around it, or periodic dimming of the star's brightness with time due to a planet blocking part of the star's light.

58. Io is very geologically active. Its atmosphere is rich in:
a) CO₂.
b) H₂.
c) sulfur compounds.
d) O₂.
e) N₂.

59. The sideways `swirling' motion of clouds in the Earth's atmosphere is a consequence of:
a) Meteoroids falling into the atmosphere.
b) The Dynamo Effect.
c) The Coriolis Effect.
d) The Solar Wind.
e) The Earth's magnetic field.

60. The troposphere is:
a) the lowest layer of the Earth's atmosphere, closest to the Earth.
b) the layer of the Earth's atmosphere that contains the ozone layer.
c) the liquid outer core of the Earth.
d) the region outside the Earth where solar wind particles are trapped by the Earth's magnetic field.
e) the outer layer of the Earth's atmosphere, which is ionized by X-rays from the Sun.

61. Which of the following is a greenhouse gas?
a) O₂.
b) CO₂.
c) N₂.
d) Argon.
e) O₃.

62. What component of our atmosphere is predominantly responsible for absorbing the UV from the Sun?
a) O₂.
b) CO₂.
c) N₂.
d) Argon.
e) O₃.

63. What is primarily responsible for protecting us from X-rays from the Sun?
a) The ionosphere.
b) The ozone layer.
c) The troposphere.
d) The Earth's magnetic field.
e) None of the above; X-rays travel freely through the Earth's atmosphere, and are not dangerous to life.

64. Which two objects have atmospheres that are mostly N₂?
a) Earth and Venus.
b) Mars and Io.
c) Uranus and Neptune.
d) Earth and Titan.
e) Mars and Venus.

65. The hydrogen-rich atmosphere of Jupiter is mostly:
a) left-over from the formation of the solar system.
b) due to outgassing from the interior of the planet.
c) due to bombardment of the surface by the solar wind.
d) caused by sublimation of polar icecaps.
e) due to hydrogen fusion in Jupiter's core.

66. The atmospheric pressure on Saturn's moon Titan is:
a) 10^-15 times that of Earth.
b) 10^-11 times that of Earth.
c) 10^-4 times that of Earth.
d) 1.6 times that of Earth.
e) 90 times that of Earth.

67. The Earth's magnetic field is:
a) Weaker than that of Venus, but stronger than the other terrestrial planets.
b) Weaker than that of Mercury and Venus, but stronger than Mars.
c) Weaker than that of Mars, but stronger than the other terrestrial planets.
d) The weakest of all the terrestrial planets.
e) The strongest of all the terrestrial planets.

68. Bombardment of the surface by solar wind particles, and gravitational capture of solar wind particles, is mainly responsible for the atmosphere of:
a) Mercury.
b) Venus.
c) Mars.
d) Titan.
e) Io.

69. The inner core of the Earth is:
a) hot, liquid, mostly metal.
b) hot, solid, mostly metal.
c) cold, solid, mostly metal.
d) hot, liquid, mostly rock.
e) scientists have no idea what the inner core of the Earth is like.

70. Infrared radiation:
a) is strongly absorbed by the N₂ and O₂ in our atmosphere.
b) is responsible for ionizing the ionosphere.
c) is absorbed by the greenhouse gases.
d) is the highest energy type of light.
e) is the longest wavelength type of light.

71. With a small telescope, `stripes' are visible on Jupiter. These are due to:
a) the scattering of light by Jupiter's atmosphere.
b) plate tectonics (Continental Drift).
c) the deflection of moving charged particles by Jupiter's magnetic field.
d) the interaction of solar wind particles with Jupiter's atmosphere.
e) circulation patterns in the atmosphere caused by convection, the rotation of the planet, and the Coriolis effect.

72. The reason the core of the Earth is very iron-rich is:
a) the iron was attracted by the strong magnetic field of the Earth.
b) tidal forces from the Moon pushed iron to the center of the Earth.
c) differentiation in the young molten Earth.
d) the Greenhouse effect.
e) the Coriolis effect.

73. A planet in a different solar system besides our own is called a/an:
a) Oort planet.
b) Kuiper planet.
c) Coriolis planet.
d) Extrasolar planet.
e) Van Allen planet.

74. In class, I did a demonstration in which I rolled a chalk-covered ball across a spinning platform. From the point of view of a viewer watching the demonstration, the ball rolls in a straight line. However, the path left on the platform by the ball was curved. This effect is called:
a) Convection.
b) Differentiation.
c) Aberration.
d) The Coriolis Effect.
e) The Dynamo Effect.

75. What protects us from UV light from the Sun?
a) The ionosphere.
b) The ozone layer.
c) The Earth's magnetic field.
d) CO², CH₄, and H₂O in the atmosphere.
e) None of the above; most of it reaches the surface of the Earth.

76. The region outside the Earth where charged particles from the solar wind are trapped by the Earth's magnetic field is called the:
a) Ozone layer.
b) Greenhouse Zone.
c) Van Allen Belts.
d) Extrasolar Belts.
e) Coriolis layer.

77. The lowest layer of our Earth's atmosphere, which has the densest gas and produces the weather we experience, is called the:
a) Troposphere.
b) Stratosphere.
c) Ionosphere.
d) Ozone layer.
e) Van Allen layer.

78. The atmosphere of Mars is mostly:
a) CO₂ and N₂.
b) Hydrogen and helium.
c) N₂ and O₂.
d) N₂ and CH₄.
e) Potassium and sodium.

79. The global magnetic field of Venus is:
a) About the same as that of Earth.
b) About 90 times greater that of Earth.
c) About 1000 times greater that of Earth.
d) Weaker than that of Earth, but stronger than that of Mercury.
e) Venus does not have a global magnetic field.

80. Seismic S waves:
a) Travel through both liquids and solids.
b) Only travel through rigid material.
c) Only travel through liquids.
d) Do not travel through either solids or liquids, just gases.
e) Only travel across the surface of the Earth; they do not penetrate the interior of the Earth.

81. The generation of the magnetic field of a planet by moving charged particles in the interior is called:
a) Differentiation.
b) The Dynamo Effect.
c) The Coriolis Effect.
d) The Greenhouse Effect.
e) Convection.

82. Visible light from the Sun heats the Earth, which re-radiates this energy in the infrared. This infrared light then get absorbed in the lower layers of the Earth's atmosphere. This process is called:
a) The Coriolis Effect.
b) The Greenhouse Effect.
c) Convection.
d) The Dynamo Effect.
e) The Van Allen Effect.

83. Which of the following is NOT true about blue light compared to red light?
a) Blue light is more likely to be scattered or absorbed in the Earth's atmosphere than red light.
b) Blue light has shorter wavelengths than red light.
c) Blue light travels faster than red light in a vacuum.
d) Blue light slows down more when traveling in glass than red light does.
e) Blue light has a higher frequency than red light.

84. The ionosphere is:
a) the lowest layer of the Earth's atmosphere, closest to the Earth.
b) the layer of the Earth's atmosphere that contains the ozone layer.
c) the liquid outer core of the Earth.
d) where most airplanes fly.
e) the outer layer of the Earth's atmosphere, which reflects AM radio waves.

85. Scientists infer that Venus likely has a liquid layer inside, like the Earth. What is the reasoning?
a) Venus has a very strong magnetic field, like the Earth.
b) Venus is spinning fast, like the Earth.
c) Venus is about the same size as Earth, so cooled at about the same rate.
d) Many earthquakes have been detected on Venus.
e) Venus has very strong Van Allen belts, like the Earth.

86. Extrasolar planets:
a) is the generic name for the four largest planets: Jupiter, Saturn, Uranus, or Neptune.
b) are brown dwarfs.
c) are dwarf planets.
d) are planets orbiting other stars besides the Sun.
e) are large objects in the Kuiper Belt.

87. For which planet or planets is the atmosphere probably mostly left over from the formation of the solar system?
a) Mercury.
b) Venus.
c) Venus, Earth, and Mars.
d) Mars.
e) The Jovian planets.

88. Which moon in our solar system has an atmospheric pressure about 1.6 times that of Earth?
a) The Earth's Moon.
b) Io.
c) Europa.
d) Ganymede.
e) Titan.

89. Which kind of seismic wave travels through both the inner and outer core of the Earth?
a) Both P waves and S waves.
b) Only P waves.
c) Only S waves.
d) Neither P or S waves.
e) Only L waves.

90. Why does Venus have so much more Greenhouse gases in its atmosphere than Earth?
a) on the Earth, some CO₂ from the atmosphere dissolves in the oceans.
b) on the Earth, planet life converts some CO₂ into O₂.
c) on Venus, the higher temperature has caused CO₂ to be released from rocks.
d) Earth is farther from the Sun, so liquid water can exist on its surface.
e) All of the above.

91. The time for the heat to escape from the interior of a planet (and therefore the time for the planet's interior to cool) is proportional to:
a) R, where R is the radius of the planet.
b) R⁴, where R is the radius of the planet.
c) 1/R, where R is the radius of the planet.
d) 1/R⁴, where R is the radius of the planet.
e) It doesn't depend upon the radius.

92. Hot spot volcanism:
a) was responsible for the Mid-Atlantic Ridge.
b) was responsible for the Hawaiian Islands.
c) was responsible for the Andes Mountains.
d) was responsible for the deep sea trench off of the western coast of South America.
e) was responsible for the Appalachian Mountains.

93. The Earth's magnetic field protects us from:
a) harmful ultraviolet photons from the Sun.
b) freezing to death: it helps keep us warm.
c) meteoroids: chunks of rocks from space that might hit the Earth.
d) the Greenhouse Effect.
e) the solar wind.

94. At the Mid-Atlantic Ridge:
a) Two continental plates are moving apart.
b) Two continental plates are colliding.
c) Two continental plates are sliding past each other, one moving north and the other south.
d) A single isolated hot spot in the mantle has created the entire Mid-Atlantic Ridge.
e) A subduction zone is present.

95. The unstable isotope uranium-235 will spontaneously decay to lead-207, with a half-life of 700 million years. This means that in a time of 1.4 billion years:
a) All of the original uranium-235 in a sample will have decayed.
b) Half of the original uranium-235 will have decayed.
c) 3/4ths of the original uranium-235 will have decayed.
d) 1/4th of the original uranium-235 will have decayed.
e) 7/8th of the original uranium-235 will have decayed.

96. The asthenosphere of the Earth is:
a) the upper level of the atmosphere, also called the ionosphere.
b) the liquid outer core of the Earth.
c) a large region around the Earth containing numerous charged particles; also called the Van Allen Belts.
d) the lowest layer of the atmosphere, where weather occurs.
e) the semi-molten upper mantle of the Earth, responsible for plate tectonics.

97. Regions where two continental plates are colliding, and one gets pulled under the surface, are called:
a) Diffraction zones.
b) Subduction zones.
c) Coriolis regions.
d) Van Allen Belts.
e) Hot spot zones.

98. What is the main process responsible for the formation of the Andes Mountains?
a) The Van Allen Belts interacting with the ionosphere.
b) The impact of a very large asteroid.
c) Sea Floor Spreading.
d) Two tectonic plates colliding.
e) Hot spot volcanism.

99. The stratosphere is the second-from-the-bottom layer of the Earth's atmosphere, being between about 15 and 50 km above the surface of the Earth. The stratosphere:
a) reflects most radio emission.
b) is primarily responsible for the Greenhouse Effect here on Earth.
c) is responsible for preventing the solar wind from hitting the surface of the Earth.
d) contains the majority of the Earth's atmosphere.
e) hosts the ozone layer.

100. Venus:
a) Has the strongest magnetic field of all of the terrestrial planets.
b) Is the fastest spinning terrestrial planet.
c) Has an atmospheric pressure that is about the same as that of Earth.
d) Is about half the diameter of Earth.
e) Has an atmosphere which is mostly CO₂.

101. Which of the following objects has an atmosphere that is mostly hydrogen and helium?
a) Mars.
b) Venus.
c) Earth.
d) Jupiter.
e) Titan.

102. Which of the following is most important in protecting us from the solar wind?
a) The ozone layer.
b) The asthenosphere.
c) The Earth's magnetic field.
d) The ionosphere.
e) The Greenhouse gases.

103. The very thin atmosphere on Mercury:
a) is left-over from the formation of the solar system.
b) is due to outgassing from the interior of the planet.
c) is due to bombardment of the surface by the solar wind.
d) is caused by sublimation of polar icecaps.
e) is caused by geysers squirting water into space.

104. The top layer of the Earth's atmosphere is called the:
a) Asthenosphere.
b) Troposphere.
c) Stratosphere.
d) Thermosphere (Ionosphere).
e) Ozone Layer.

105. Which kind of light from Astronomical objects is mostly reflected by the ionosphere, thus cannot be observed from the surface of the Earth?
a) Ultraviolet.
b) Long wavelength radio (greater than 100 meters).
c) Infrared.
d) X-rays.
e) All of the above.

106. Which of the following objects has the highest surface density of craters on its surface?

a) Callisto.
b) Earth.
c) Ganymede.
d) Europa.
e) Io.

107. The colorful displays produced when solar wind particles interact with the Earth's atmosphere are called:
a) The Coriolis Effect.
b) The Greenhouse Effect.
c) The Dynamo Effect.
d) Aurora.
e) Differentiation.

108. Which of the following objects has an atmosphere rich in sulfur compounds?
a) Mars.
b) Callisto.
c) Titan.
d) Io.
e) Mercury.

109. The ionosphere of the Earth:

a) blocks most of the infrared light from the Sun.
b) contains the ozone layer.
c) is responsible for the Earth's magnetic field.
d) is the lowest layer of the atmosphere.
e) is ionized by high energy photons from the Sun.

110. At the San Andreas Fault in California:
a) Two continental plates are pulling apart, and molten lava is flowing up, creating new planetary crust.
b) Two continental plates are sliding past each other.
c) Two continental plates are colliding head-on, and one plate is being pushed up to form a mountain range, while the other plate is forced underneath.
d) There is a single isolated `hot spot' in the mantle underneath the fault, causing geological activity.
e) There is a subduction zone.

111. Which of the following objects has an atmosphere that is mostly carbon dioxide?
a) Mars.
b) Mercury.
c) Earth.
d) Jupiter.
e) Titan.

112. CO₂ in our atmosphere:
a) Absorbs most of the UV from the Sun.
b) Is efficient in absorbing IR light.
c) Protects us from the solar wind.
d) Is produced by plants by photosynthesis.
e) Reflects long wavelength radio waves.

113. The atmosphere of Neptune:
a) is mostly hydrogen and helium.
b) is mostly nitrogen and carbon dioxide.
c) is mostly carbon dioxide and sulfur compounds.
d) is mostly oxygen and argon.
e) Neptune does not have an atmosphere, as far as we know.

114. The mesosphere is the second-from-the-top layer of the Earth's atmosphere, being between about 50 km and 100 km above the surface of the Earth. The mesosphere:
a) reflects most radio emission from space.
b) is primarily responsible for the Greenhouse Effect here on Earth.
c) is responsible for preventing the solar wind from hitting the surface of the Earth.
d) contains the majority of the Earth's atmosphere.
e) none of the above.

115. Which of the following is a subduction zone?
a) The Mid-Atlantic Ridge.
b) The region around the Hawaiian Islands.
c) Off the coast of South America near the Andes Mountains.
d) The San Andreas Fault.
e) All of the above.

116. Which of the following objects has the lowest surface density of impact craters on its surface?

a) Callisto.
b) Venus.
c) Ganymede.
d) Europa.
e) Io.

117. Which of the following has the highest atmospheric pressure at its surface?
a) Mars.
b) Ganymede.
c) Titan.
d) Mercury.
e) Earth.

118. The ozone layer is:
a) in the Earth's troposphere.
b) in the Earth's ionosphere.
c) in the Van Allen belts.
d) in the upper part of the Earth's mantle.
e) in the Earth's stratosphere.

119. Which of the following has the strongest global magnetic field?

a) Earth.
b) Venus.
c) The Moon.
d) Mercury.
e) Mars.

120. If humans colonize Mars, which of the following is a consideration they need to worry about, as far as their long-term safety?
a) An atmosphere which is mostly sulfuric acid.
b) No global magnetic field.
c) A too-strong Greenhouse Effect, causing too high temperatures.
d) Too many active volcanoes.
e) Too strong a gravitational field, making walking too difficult.

121. The global magnetic field of Mars is caused by:
a) convection in the asthenosphere (upper mantle).
b) the solid inner core of Mars, which acts like a giant magnet.
c) moving charged particles in the liquid outer core of Mars.
d) charged particles in the solar wind interacting with Mars' atmosphere.
e) Mars does not have a global magnetic field.

122. Which of the following are the most common molecules in the Earth's atmosphere?
a) N₂ and O₂.
b) CO₂, CH₄, and H₂O.
c) H₂ and He.
d) N₂ and H₂.
e) O₂ and CO₂.

123. Mercury:
a) Has the second strongest magnetic field of all of the terrestrial planets.
b) Has a sidereal day equal to 24 hours 37 minutes.
c) Is tidally locked to the Sun.
d) Has a surface atmospheric pressure that is 1.6 times greater than that of Earth.
e) Has no global magnetic field.

124. Which object in our solar system has a sulfur-rich atmosphere due to on-going volcanic activity?
a) The Earth's Moon.
b) Mercury.
c) Io.
d) Mars.
e) Callisto.

125. The sideways `swirling' motion of clouds in the Earth's atmosphere is a consequence of:
a) The Dynamo Effect.
b) Convection combined with the rotation of the Earth.
c) The Solar Wind combined with the rotation of the Earth.
d) The Earth's magnetic field.
e) Outgassing from the planet.

126. Which of the following is NOT true about the ionosphere of the Earth?
a) It reflects very long wavelength radio waves (greater than 100 meters in wavelength).
b) It is the outermost layer of the Earth's atmosphere.
c) It is ionized by high energy photons from the Sun.
d) The gas pressure in the ionosphere is lower than in any other part of the atmosphere.
e) Another name for the ionosphere is the Van Allen Belt.

127. Which of the following spacecraft has discovered many extrasolar planets by searching for planetary transits?
a) Messenger.
b) Kepler.
c) New Horizons.
d) Voyager.
e) Viking.

128. The unstable isotope carbon-14 will spontaneously decay to nitrogen-14, with a half-life of 5730 years. This means:
a) In a time of 5730 years, all of the carbon-14 will be gone.
b) In a time of 2 X 5730 = 11,460 years, about one quarter of the carbon-14 in the original sample will be left.
c) In a time of 2 X 5730 = 11,460 years, all of the carbon-14 will have changed into nitrogen-14.
d) Each carbon-14 atom lasts 5730 years, then decays.
e) In a time of 3 X 5730 = 17,190 years, about one quarter of the carbon-14 in the original sample will be left.

129. The Greenhouse Effect is mostly caused by what type of light being absorbed by molecules in the Earth's lower atmosphere, causing an increase in the temperature of the atmosphere?
a) Ultraviolet.
b) Radio.
c) Infrared.
d) Visible.
e) X-ray.

130. Rank the surfaces of the following planets in terms of the average age of the rocks, from youngest to oldest?
a) Mercury, Venus, Earth, Mars.
b) Venus, Earth, Mars, Mercury.
c) Earth, Venus, Mars, Mercury.
d) Earth, Mars, Venus, Mercury.
e) Earth, Mars, Mercury, Venus.

131. How many times does Mercury spin on its axis (relative to the stars), for each orbit around the Sun (relative to the stars)?
a) once.
b) 1 1/2 times.
c) twice.
d) 360 times.
e) Mercury does not spin on its axis.

132. The `scarps' seen on Mercury are:
a) Dry river beds.
b) Very large impact basins that have filled with molten lava, that subsequently hardened.
c) Long cliffs.
d) Huge storms in the atmosphere.
e) Subduction zones.

133. Which of the following moons is spiraling in towards its planet, and will eventually be torn apart by tidal forces?
a) The Earth's Moon.
b) Titan.
c) Ganymede.
d) Callisto.
e) Triton.

134. Approximately how frequently does high tide happen here on Earth?
a) Once every six months.
b) Once a month.
c) Twice a month.
d) Twice a day.
e) Once a day.

135. The mountain ranges on the Moon were mostly produced by:
a) Convection under the surface, cracking the surface, producing volcanic mountain, like the Mid-Atlantic Ridge on Earth.
b) Two continental plates colliding, pushing up a mountain range, as in the formation of the Andes Mountains on Earth.
c) Large objects hitting the surface, pushing up mountain ranges around the impact basins.
d) Hot spot volcanism in the Moon's mantle.
e) Subduction Zones.

136. The large dark spots one can see on the face of the Moon without a telescope are:
a) very cratered, compared to the rest of the Moon.
b) very mountainous, compared to the rest of the Moon.
c) smooth lava flows.
d) composed of the oldest known rocks in the solar system.
e) about the diameter of the Earth.

137. According to most scientists, the Moon probably formed:
a) from a collision of a large planetesimal with the Earth.
b) from the Earth cracking and breaking apart into two pieces.
c) elsewhere in the solar system, and was gravitationally captured.
d) simultaneously with the Earth, as a "double planet".
e) there is no evidence for any of the above scenarios.

138. On the Moon, the maria are mostly only seen on the:
a) highlands.
b) far side.
c) dark side.
d) southern hemisphere.
e) near side.

139. Our best views of the surface of Mercury were obtained:
a) By the Magellan spacecraft, using radar mapping.
b) By the Galileo spacecraft.
c) By the Voyager 2 spacecraft.
d) By the Mariner 10 and Messenger spacecraft.
e) By the Hubble Space Telescope.

140. The highlands on the Moon:
a) are darker in color than the maria.
b) are more cratered than the maria.
c) are younger than the maria.
d) were caused by plate tectonics.
e) were caused by hot spot volcanism.

141. The Moon rocks brought back to Earth by the Apollo astronauts:
a) are between one million and 500 million years old.
b) are between 2 and 3 billion years old.
c) are between 3.2 and 4.4 billion years old.
d) are about 10 billion years old.
e) are the oldest rocks known in the solar system.

142. The Moon has many more craters than the Earth. This is because:
a) The Moon protected the Earth from impacts: most of the large objects hit the moon rather than the Earth.
b) The Earth's atmosphere stopped all the potentially damaging objects.
c) The Moon was much more volcanic than the Earth in the past, and these volcanoes caused the craters on the Moon.
d) Plate tectonics has returned cratered surface layers to the Earth's interior and weathering has obliterated more recent craters on the Earth.
e) Sheer luck: just by chance the Earth hasn't been hit by as many objects as the Moon.

Answers: 1c, 2b, 3e, 4b, 5c, 6b, 7c, 8e, 9a, 10a, 11e, 12b, 13d, 14b, 15a, 16a, 17b, 18e, 19c, 20d, 21a, 22a, 23e, 24c, 25e, 26a, 27a, 28d, 29d, 30a, 31a, 32d, 33e, 34e, 35e, 36e, 37d, 38c, 39c, 40d, 41a, 42d, 43e, 44d, 45e, 46b, 47d, 48c, 49e, 50a, 51c, 52b, 53e, 54c, 55d, 56a, 57e, 58c, 59c, 60a, 61b, 62e, 63a, 64d, 65a, 66d, 67e, 68a, 69b, 70c, 71e, 72c, 73d, 74d, 75b, 76c, 77a, 78a, 79e, 80b, 81b, 82b, 83c, 84e, 85c, 86d, 87e, 88e, 89b, 90e, 91a, 92b, 93e, 94a, 95c, 96e, 97b, 98d, 99e, 100e, 101d, 102c, 103c, 104d, 105b, 106a, 107d, 108d, 109e, 110b, 111a, 112b, 113a, 114e, 115c, 116e, 117c, 118e, 119a, 120b, 121e, 122a, 123a, 124c, 125b, 126e, 127b, 128b, 129c, 130c, 131b, 132c, 133e, 134d, 135c, 136c, 137a, 138e, 139d, 140b, 141c, 142d.