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Suppose we use a baseball to represent Earth. On this scale, the other terrestrial worlds (Mercury, Venus, the Moon, and Mars) would range in size approximately from that of _________. |
a golf ball to a baseball |
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From center to surface, which of the following correctly lists the interior layers of a terrestrial world? |
core, mantle, crust |
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What do we mean when we say that the terrestrial worlds underwent differentiation? |
When their interiors were molten, denser materials sank toward their centers and lighter materials rose toward their surfaces. |
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A terrestrial world’s lithosphere is ________. |
a layer of relatively strong, rigid rock, encompassing the crust and part of the mantle |
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The two most important processes in heating the interiors of the terrestrial worlds are: |
… |
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Which of the following is an example of convection? |
Warm air expanding and rising while cooler air contracts and fall. |
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What is a magnetosphere? |
a region of space around a planet in which the planet’s magnetic field can trap charged particles |
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The processes responsible for virtually all surface geology are _________. |
impact cratering, volcanisms, tectonics, and erosion |
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In the context of planetary geology, what do we mean by outgassing? |
the release by volcanism of gases that had been trapped in a planetary interior |
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Which of the following is not an example of tectonics? |
The gradual disappearance of a crater rim as a result of wind and rain. |
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Suppose we represent Earth with a basketball. On this scale, most of the air in Earth’s atmosphere would fit in a layer that is _________. |
about the thickness of a sheet of paper |
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Why is the sky blue (on Earth)? |
Because molecules scatter blue light more effectively than red light |
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Which of the following is the most basic definition of a greenhouse gas? |
a gas that absorbs infrared light |
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Which of the following best describes the lunar maria? |
relatively smooth, flat plains on the Moon |
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Why does the Moon have a layer of "powdery soil" on its surface? |
It is the result of countless tiny impacts by small particles striking the Moon. |
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What observational evidence supports the idea that Mercury once shrank by some 20 kilometers in radius? |
the presence of many long, tall cliffs |
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Olympus Mons is ______. |
a huge volcano on Mars |
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Which of the following is not a similarity between Earth and Mars? |
Both planets have similar atmospheric pressure. |
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All of the statements below are true. Which one gives the primary reason why the surface of Venus today is some 450°C hotter than the surface of Earth? |
Venus has a much stronger greenhouse effect than Earth. |
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What do we mean by a runaway greenhouse effect? |
a greenhouse effect that keeps getting stronger until all of a planet’s greenhouse gases are in its atmosphere |
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On average, how fast do the plates move on the Earth? |
a few centimeters per year |
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In the context of plate tectonics, what is a subduction zone? |
A place where a seafloor plate is sliding under a continental plate. |
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What is the importance of the carbon dioxide (CO2) cycle? |
It regulates the carbon dioxide concentration of our atmosphere, keeping temperatures moderate. |
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Earth has been gradually warming over the past few decades. Based on a great deal of evidence, scientists believe that this warming is caused by _____. |
human activities that increase the concentration of greenhouse gases in Earth’s atmosphere |
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Based on all we know about the terrestrial worlds, what single factor appears to play the most important role in a terrestrial planet’s geological destiny? |
its size |
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The cores of the terrestrial worlds are made mostly of metal because ______. |
metals sunk to the centers a long time ago when the interiors were molten throughout |
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The reason that small planets tend to lose interior heat faster than larger planets is essentially the same as the reason that _________. |
a large baked potato takes longer to cool than a small baked potato |
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Suppose we had a device that allowed us to see Earth’s interior. If we looked at a typical region of the mantle, what would we see happening? |
not much – on human time scales, the mantle looks like solid rock |
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Recent evidence suggests that Mars once had a global magnetic field. Assuming this is true, which of the following could explain why Mars today lacks a global magnetic field like that of Earth? |
Mars’s interior has cooled so much its molten core layer no longer undergoes convection. |
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What are the two geological features that appear to set Earth apart from other terrestrial worlds in our solar system? |
plate tectonics and a high level of erosion |
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Which of the following general statements about Earth’s atmosphere is not true? |
The nitrogen and oxygen in Earth’s atmosphere keep the surface pleasantly warm. |
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Which of the following best describes how the greenhouse effect works? |
A planet’s surface absorbs visible sunlight and returns this absorbed energy to space as infrared light. Greenhouse gases slow the escape of this infrared radiation, which thereby heats the lower atmosphere. |
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Suppose that Earth’s atmosphere had no greenhouse gases. Then Earth’s average surface temperature would be ________. |
well below the freezing point of water |
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Most of the Moon’s surface is densely covered with craters, but we find relatively few craters within the lunar maria. What can we conclude? |
The maria formed after the heavy bombardment ended. |
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Which of the following best describes the geological histories of the Moon and Mercury? |
Early in their histories, they suffered many impacts and experienced some volcanism and tectonics, but they now have little geological activity at all. |
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What makes us think that Mars must once have had an atmosphere that was warmer and had higher surface pressure? |
The atmosphere is too cold and thin for liquid water today, yet we see evidence that water flowed on the surface in the past. |
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All the following statements about Mars are true. Which one might have led to a significant loss of atmospheric gas to space? |
Mars lost any global magnetic field that it may once have had. |
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Many scientists suspect that Venus has a stronger and thicker lithosphere than Earth. If this is true, which of the following could explain it? |
The high surface temperature that has "baked out" all the liquid water from Venus’s crust and mantle |
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All the following statements about Venus are true. Which one offers evidence of a global repaving about a billion years ago? |
Venus has relatively few impact craters and these craters are distributed fairly evenly over the entire planet. |
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Which of the following best explain what we think happened to outgassed water vapor on Venus? |
Ultraviolet light split the water molecules, and the hydrogen then escaped to space. |
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Why are there fewer large impact craters on the Earth’s seafloor than on the continents? |
The crust on seafloors is younger than on continents, so it has had less time in which to suffer impacts. |
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Which two factors are most important to the existence of plate tectonics on Earth? |
mantle convection and a thin lithosphere |
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Why does Earth have so little carbon dioxide in its atmosphere compared to Venus? |
Earth has just as much carbon dioxide as Venus, but most of it is locked up in carbonate rocks rather than being free in the atmosphere. |
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Which two factors are critical to the existence of the carbon dioxide (CO2) cycle on Earth? |
plate tectonics and liquid water oceans |
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Suppose Earth were to cool down a little. How would the carbon dioxide cycle tend to restore temperatures to normal? |
Cooler temperatures lead to slower formation of carbonate minerals in the ocean, so carbon dioxide released by volcanism builds up in the atmosphere and strengthens the greenhouse effect. |
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Which of the following correctly lists two key pieces of evidence that, together, indicate that we should expect human activity to cause global warming? |
(1) Carbon dioxide tends to make planets warmer than they would be otherwise; (2) Measurements demonstrate that human activity is raising the carbon dioxide concentration in the atmosphere. |
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The choices below describe four hypothetical planets. Which one would you expect to have the hottest interior? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.) |
Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months. |
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The choices below describe four hypothetical planets. Which one’s surface would you expect to be most crowded with impact craters? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.) |
Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days. |
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The choices below describe four hypothetical planets. Which one would you expect to have the most features of erosion? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.) |
Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours. |
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