Astro Ch. 7

The cores of the terrestrial worlds are made mostly of metal because ______. the core contained lots of radioactive elements that decayed into metals over billions of years, convection gradually brought dense metals downward to the core metals sunk to the centers a long time ago when the interiors were molten throughout the terrestrial worlds as a whole are made mostly of metal

The reason that small planets tend to lose interior heat faster than larger planets is essentially the same as the reason that _________. thunderstorms tend to form on hot summer days gas bubbles form and rise upward in boiling water a large baked potato takes longer to cool than a small baked potato Earth contains more metal than the Moon

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 dense metals falling downward while low-density rock rises upward hot molten rock rising upward throughout the mantle and cool, solid rock falling downward a rapid, up and down churning of the material in the mantle

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 is too far from the Sun to have a global magnetic field. Mars rotates much slower than the Earth. Mars's interior has cooled so much its molten core layer no longer undergoes convection. The Martian core is made of rock, while Earth's core is made of metal.

What are the two geological features that appear to set Earth apart from other terrestrial worlds in our solar system? significant volcanism and tectonics a dense core and plate tectonics mantle convection and a thick atmosphere plate tectonics and a high level of erosion

Which of the following general statements about Earth's atmosphere is not true? The oxygen in our atmosphere was released by living organisms. Without the relatively rare gas called ozone, Earth's surface would be bathed in dangerous ultraviolet light from the Sun. Gas high in the atmosphere absorbs dangerous X rays from the Sun. The nitrogen and oxygen in Earth's atmosphere keep the surface pleasantly warm.

Which of the following best describes how the greenhouse effect works? The greenhouse effect is caused primarily by ozone, which absorbs ultraviolet light and thereby makes the atmosphere much hotter than it would be otherwise. Greenhouse gases absorb infrared light coming from the Sun, and this absorbed sunlight heats the lower atmosphere and the surface. Greenhouse gases absorb X rays and ultraviolet light from the Sun, and this absorbed radiation then heats the atmosphere and the surface. 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.

Suppose that Earth's atmosphere had no greenhouse gases. Then Earth's average surface temperature would be ________. slightly cooler, but still above freezing well below the freezing point of water about the same as it is now slightly warmer, but still well below the boiling point of water

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? Erosion affects the maria more than it affects other regions of the Moon. The maria formed after the heavy bombardment ended. The regions of the maria were hit by fewer impacts than the densely cratered regions. The maria formed within the past 1 billion years.

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. All four geological processes were important in their early histories, but only impact cratering still reshapes their surfaces today. Impact cratering is the only major geological process that has affected their surfaces. Impact cratering shaped these worlds early in their histories. Then, during the past few million years, they were reshaped by episodes of volcanism and tectonics.

What makes us think that Mars must once have had an atmosphere that was warmer and had higher surface pressure? We think it for purely theoretical reasons, based on calculations showing that the Sun has brightened with time. The presence of inactive volcanoes on Mars tells us that there must once have been a lot of outgassing, and hence a thicker atmosphere. The atmosphere is too cold and thin for liquid water today, yet we see evidence that water flowed on the surface in the past. The fact that parts of Mars have a lot of craters tell us that Mars must once have been much warmer.

All the following statements about Mars are true. Which one might have led to a significant loss of atmospheric gas to space? The axis tilt of Mars is thought to change significantly with time. Mars probably once had a much higher density of greenhouse gases in its atmosphere than it does today. Outgassed water molecules are split apart, and the oxygen then reacts chemically with surface rock on Mars. Mars lost any global magnetic field that it may once have had.

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 apparent lack of plate tectonics on Venus The slow rotation of Venus The high surface temperature that has "baked out" all the liquid water from Venus's crust and mantle The smaller size of Venus, which has allowed it to lose much more internal heat than Earth

All the following statements about Venus are true. Which one offers evidence of a global repaving about a billion years ago? Venus has many circular features, called coronae, which appear to be tectonic in origin. Venus has relatively few impact craters and these craters are distributed fairly evenly over the entire planet. Venus's largest features are three elevated regions that look somewhat like continents. Venus appears to lack any water that could lubricate the flow of rock in its crust and mantle.

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. Water was removed from the atmosphere by chemical reactions with surface rock. It is frozen as water ice in craters near the poles. It turned into carbon dioxide by reacting with nitrogen in Venus's atmosphere.

Why are there fewer large impact craters on the Earth's seafloor than on the continents? Erosion erases impact craters must faster on the ocean bottom than on land. The crust on seafloors is younger than on continents, so it has had less time in which to suffer impacts. Most impacts occur on the land. The oceans slow large impactors and prevent them from making craters.

Which two factors are most important to the existence of plate tectonics on Earth? mantle convection and a thin lithosphere oxygen in the atmosphere and mantle convection the existence of life and oxygen in the atmosphere Earth's liquid outer core and solid inner core

Why does Earth have so little carbon dioxide in its atmosphere compared to Venus? Chemical reactions turned Earth's carbon dioxide into nitrogen. 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. Earth's volcanoes outgassed far less carbon dioxide than those on Venus. Earth once had a lot of carbon dioxide, but it was lost to space during the heavy bombardment early in our solar system's history.

Which two factors are critical to the existence of the carbon dioxide (CO2) cycle on Earth? active volcanism and active tectonics plate tectonics and liquid water oceans life and active volcanism life and atmospheric oxygen

Suppose Earth were to cool down a little. How would the carbon dioxide cycle tend to restore temperatures to normal? Cooler temperatures cause volcanoes to become more active, so they release more carbon dioxide into the atmosphere than they do when temperatures are warmer. Cooler temperatures mean more ice and more erosion, which somehow makes the planet warm up. Cooler temperatures allow carbon dioxide to form rain and rain out of the atmosphere. 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.

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) We can learn about past climate from ice cores; (2) Ice cores show that Earth naturally has cooler and warmer periods. (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. (1) The burning of fossil fuels is a form of human activity; (2) Human activity is always bad for the environment. (1) The carbon dioxide cycle regulates Earth's climate; (2) Human activity has disrupted the carbon dioxide cycle.

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: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days. Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours. Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months. Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours.

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 Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours. Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months. Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours. Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days.

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: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months. Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days. Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours. Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours.

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 dust speck to a golf ball a dust speck to a basketball a golf ball to a beach ball a golf ball to a baseball

From center to surface, which of the following correctly lists the interior layers of a terrestrial world? mantle, crust, core mantle, core, crust core, mantle, crust core, crust, lithosphere

What do we mean when we say that the terrestrial worlds underwent differentiation? The five terrestrial worlds all started similarly but ended up looking quite different. Their surfaces show a variety of different geological features resulting from different geological processes. They lost interior heat to outer space. When their interiors were molten, denser materials sank toward their centers and lighter materials rose toward their surfaces.

A terrestrial world's lithosphere is ________. a layer of hot, molten rock encompassing the core and part of the mantle a thin layer of rock that lies between the mantle and crust the interior region in which the planet's magnetic field is generated a layer of relatively strong, rigid rock, encompassing the crust and part of the mantle

The two most important processes in heating the interiors of the terrestrial worlds are: (1) Heat deposited by the process of formation; (2) heat that came from the gravitational potential energy of incoming planetesimals. (1) Heat from convection; (2) heat from thermal radiation. (1) Volcanism; (2) tectonics. (1) Heat deposited by the process of formation; (2) heat released by radioactive decay.

Which of the following is an example of convection? Different kinds of material separating by density, like oil and water. Rocks sinking in water. Warm air expanding and rising while cooler air contracts and fall. Gas bubbling upward through a liquid.

What is a magnetosphere? the region in a planet's atmosphere in which auroras occur a region of space around a planet in which the planet's magnetic field can trap charged particles the layer of a planet in which its magnetic field is generated the uppermost layer of any planetary atmosphere

The processes responsible for virtually all surface geology are _________. eruptions, lava flows, and outgassing convection, conduction, and radiation impact cratering, volcanisms, tectonics, and erosion accretion, differentiation, and radioactive decay

In the context of planetary geology, what do we mean by outgassing? another name for a volcanic eruption the loss of atmospheric gas to outer space the release by volcanism of gases that had been trapped in a planetary interior the evaporation of water that adds water vapor (a gas) to an atmosphere

Which of the following is not an example of tectonics? The gradual disappearance of a crater rim as a result of wind and rain. The slow movement of Earth's lithospheric plates. The stretching of the crust by underlying mantle convection. The formation of a cliff when the lithosphere shrinks.

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 6 inches thick about a half-inch thick about the thickness of a sheet of paper about an inch thick

Why is the sky blue (on Earth)? Because molecules scatter red light more effectively than blue light Because deep space is blue in color No one knows - this is one of the great mysteries of science Because molecules scatter blue light more effectively than red light Because the Sun emits mostly blue light

Which of the following is the most basic definition of a greenhouse gas? a gas that makes a planet much hotter than it would be otherwise, even in small amounts a gas that reflects a lot of sunlight a gas that absorbs infrared light a gas that keeps warms air from rising, and therefore warms the surface

Which of the following best describes the lunar maria? mountainous regions on the Moon frozen oceans of liquid water on the Moon densely cratered regions on the Moon relatively smooth, flat plains on the Moon

Why does the Moon have a layer of "powdery soil" on its surface? It exists because the Moon accreted from powdery material after a giant impact blasted the Earth. It is the result of countless tiny impacts by small particles striking the Moon. It is made by the same processes that make powdery sand on Earth. Recent, large impacts shattered lunar rock to make this soil.

What observational evidence supports the idea that Mercury once shrank by some 20 kilometers in radius? the presence of many long, tall cliffs the characteristics of the Caloris Basin the presence of many impact craters Mercury's unusually high density

Olympus Mons is ______. a great canyon on Mars a huge volcano on Mars a huge volcano on Venus a large lava plain on the Moon

Which of the following is not a similarity between Earth and Mars? Both planets have similar atmospheric pressure. Both planets have polar caps. Both planets have a similar axis tilt and therefore both have seasons. Both planets have similar day lengths.

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 higher reflectivity than Earth. Venus has a much stronger greenhouse effect than Earth. Venus has a higher atmospheric pressure than Earth. Venus is only about 73% as far from the Sun as Earth.

What do we mean by a runaway greenhouse effect? a greenhouse effect that heats a planet so much that its surface rock melts a greenhouse effect that starts on a planet but later disappears as gases are lost to space a greenhouse effect that keeps getting stronger until all of a planet's greenhouse gases are in its atmosphere a process that heats a planet like a greenhouse effect, but that involves a completely different mechanism of heating that doesn't actually involve greenhouse gases

On average, how fast do the plates move on the Earth? a few millimeters per century a few centimeters per year a few kilometers per year about 1 mile per hour

In the context of plate tectonics, what is a subduction zone? A place where two continental plates are colliding. A place where two plates are pulling apart. A place where two plates are slipping sideways against one another. A place where a seafloor plate is sliding under a continental plate.

What is the importance of the carbon dioxide (CO2) cycle? It allows for an ultraviolet-absorbing stratosphere. It regulates the carbon dioxide concentration of our atmosphere, keeping temperatures moderate. It will prevent us from suffering any consequences from global warming. It makes the growth of continents possible.

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 _____. the human release of chemicals called CFCs into the stratosphere the fact that our politicians spout a lot of hot air human activities that increase the concentration of greenhouse gases in Earth's atmosphere the increase in forest fires during recent years

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? whether or not it has liquid water its size its distance from the Sun its composition