Astronomy 101 Exam 4 – Flashcards

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

Based on its surface features, the most important event on Venus in the past billion years or so was _______. -the onset of mantle convection, which caused Venus's lithosphere to split into plates like those on Earth -the impact of an unusually large asteroid that left a deep scar on one side of the planet -a global "repaving" that erased essentially all the surface features that had existed earlier -the eruption of a giant volcano that formed one of Venus's "continents"

Which of the following does NOT provide evidence that Mars once had abundant liquid water on its surface? -the presence of canali, discovered in the late 1800s by Giovanni Schiaparelli and mapped by Percival Lowell -the presence of features that look like dried-up riverbeds -the presence of very old craters that appear to have been eroded by rain -the presence of "blueberries" made of the mineral hematite

What are the basic requirements for a terrestrial world to have a global magnetic field? -a core layer of molten, convecting material and sufficiently rapid rotation -a metal core and rapid rotation -a metal core, a rocky mantle, and sufficiently rapid rotation -a core that has a molten layer and a mantle that has convection

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

A terrestrial world's lithosphere is ________. -a layer of hot, molten rock encompassing the core and part of the mantle -a layer of relatively strong, rigid rock, encompassing the crust 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

The major processes that heat the interiors of the terrestrial worlds are __________. -(1) heat deposited as the planets were built from planetesimals; (2) heat of accretion; (3) heat that came from the gravitational potential energy of incoming planetesimals -(1) heat deposited as the planets were built from planetesimals; (2) heat deposited as the planets underwent differentiation; (3) heat released by radioactive decay -(1) heat of accretion; (2) heat from convection; (3) heat from thermal radiation -(1) volcanism; (2) tectonics; (3) erosion

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

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

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

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

Shown below are the four terrestrial planets of our solar system. Assume that all the planets started out equally hot inside. Rank the planets based on their expected cooling rates, from fastest cooling to slowest cooling.

Shown following are three terrestrial planets of our solar system. Rank the planets based on the amount of time the surface of the planet has had a moderate to high level of volcanic/tectonic activity, from longest to shortest.

About how long would it take for a footprint to be erased? (Hints: Use the Moon's surface area to determine the impact rate per square centimeter, and estimate the size of a footprint.) -≈100days -≈10years -≈1,000years -≈1,000,000years

Assuming that features you see on Mars are similar to features found on Earth, what would a casual inspection of the interactive photo of Mars lead you to suspect about water on Mars? -Abundant surface water is found in large, brownish pools inside craters. -There are numerous small streams flowing with water. -Surface water only exists as frozen ice. -No surface water currently exists in any form.

Which of the following Mars surface features provides dramatic evidence that volcanism has played a role in shaping the surface of Mars? -the polar caps -the southern highlands -Valles Marineris -Olympus Mons

When you zoom in on the section labeled "Southern Highlands," which geologic processes are most clearly evident? -volcanism and erosion -impact cratering and erosion -impact cratering and volcanism -tectonics and erosion -volcanism and tectonics

Which describes our understanding of flowing water on Mars? -It was never important. -It was important once, but no longer. -It is a major process on the Martian surface today.

How many of the five terrestrial worlds are considered "geologically dead"? -none -two -four

What is the longest-lasting internal heat source responsible for geological activity? -accretion -radioactive decay -sunlight

In general, what kind of planet would you expect to have the thickest lithosphere? -a large planet -a small planet -a planet far from the Sun

Which of a planet's fundamental properties has the greatest effect on its level of volcanic and tectonic activity? -size -distance from the Sun -rotation rate

Based on Planet Z's size, orbital distance, and rotation rate, which of the following properties is it likely to have? Check all that apply. -seasons -erosion due to liquid water -polar ice caps -active volcanoes -active tectonics -strong winds and violent storms -a surface crowded with impact craters -an atmosphere produced by outgassing

You have found that Planet Z should have active tectonics and volcanism and an atmosphere produced by volcanic outgassing. What single factor explains why the planet should have these characteristics? Planet Z: -has a slow rotation rate. -has a large size for a terrestrial planet. -closely orbits its star. -lacks axis tilt.

In Part A, you found that Planet Z should not have polar ice caps or liquid water. What single change to Planet Z's characteristics would allow it to have these things? -a larger axis tilt -a larger size -a greater distance from its star -a smaller size

In Part A, you found that Planet Z should not have strong winds and violent storms. What single change to Planet Z's characteristics would cause it to have strong winds and violent storms? -a greater distance from its star -a faster rotation rate -a smaller size -a larger axis tilt

In Part A, you found that Planet Z should not have seasons. What single change to Planet Z's characteristics would cause it to have seasons? -a greater distance from its star -a faster rotation rate -a larger axis tilt -a smaller size

What do we conclude if a planet has few impact craters of any size? -The planet was never bombarded by asteroids or comets. -Its atmosphere stopped impactors of all sizes. -Other geological processes have wiped out craters.

What is the name of the outer rigid layer of a planet? -crust -mantle -lithosphere

Just as the surface area-to-volume ratio depends on size, so can other properties. To see how, suppose that your size suddenly doubled-that is, your height, width, and depth all doubled. (For example, if you were 5 feet tall before, you now are 10 feet tall.) By what factor has your waist size increased? -1 -2 -4 -8

Just as the surface area-to-volume ratio depends on size, so can other properties. To see how, suppose that your size suddenly doubled-that is, your height, width, and depth all doubled. (For example, if you were 5 feet tall before, you now are 10 feet tall.) How much more material will be required for your clothes? (Hint: Clothes cover the surface area of your body.) -1 -2 -4 -8

Just as the surface area-to-volume ratio depends on size, so can other properties. To see how, suppose that your size suddenly doubled-that is, your height, width, and depth all doubled. (For example, if you were 5 feet tall before, you now are 10 feet tall.) By what factor has your weight increased? (Hint: Weight depends on the volume of your body.) -1 -2 -4 -8

Just as the surface area-to-volume ratio depends on size, so can other properties. To see how, suppose that your size suddenly doubled-that is, your height, width, and depth all doubled. (For example, if you were 5 feet tall before, you now are 10 feet tall.) The pressure on your weight-bearing joints depends on how much weight is supported by the surface area of each joint. How has this pressure changed? -1 -2 -4 -8

Listed below are geographic features of the terrestrial worlds. In each case, identify the geological process: impact cratering, volcanism, erosion, or tectonics (where tectonics is any large-scale processes affecting the structure of the planetary crust), most responsible for the feature described. Match the geographic feature to the appropriate geologic process.

1. The slowly increasing distance between South America and Africa is due to

2. Old Faithful Geyser at Yellowstone National Park in the United States acquires its energy from a

3. Layered __________________ exposed by erosion can be seen when looking at the Grand Canyon in the United States.

4. Australia is composed of relatively old and thick

5. The extremely deep ocean Marianas Trench is a result of

6. ____________________ found in the Atlantic Ocean between North America and Europe is composed of dense and relatively young rock.

7. The earthquakes that occur in Southern California generally occur above a

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

Which of the following is not generally true of all the terrestrial world lithospheres? -The thickness of the lithosphere depends on interior temperature, with cooler interiors leading to thicker lithospheres. -The lithosphere extends from somewhere in the mantle all the way to the surface. -The lithosphere is broken into a set of large plates that float upon the softer rock below. -Rock in the lithosphere is stronger than rock beneath it.

Which internal heat source still generates heat within the terrestrial worlds today? -Heat of accretion. -Heat from differentiation -Heat from convection. -Heat from radioactive decay.

The reason that small planets tend to lose interior heat faster than larger planets is essentially the same as the reason that ________. -gas bubbles form and rise upward in boiling water -a large baked potato takes longer to cool than a small baked potato -thunderstorms tend to form on hot summer days -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? -dense metals falling downward while low-density rock rises upward -not much - on human time scales, the mantle looks like solid rock -a rapid, up and down churning of the material in the mantle -hot molten rock rising upward throughout the mantle and cool, solid rock falling downward

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

Which of the following most likely explains why Venus does not have a global magnetic field like Earth? -Its rotation is too slow. -It does not have a metallic core. -It has too thick of an atmosphere. -Unlike Earth, Venus does not have a liquid outer core.

You discover an impact crater that is 10 kilometers across. Which of the following can you conclude? -It was created by the impact of an object about 1 kilometer across. -It was created within the past 10 million years. -It was created by the impact of an object about 10 kilometers across. -It was created within the past 1 billion years.

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 maria formed within the past 1 billion years. -The regions of the maria were hit by fewer impacts than the densely cratered regions.

Which of the following is the underlying reason why Venus has so little wind erosion? -its thick atmosphere -its slow rotation -it's relatively close distance to the Sun -its small size

Which of the following best describes the geological histories of the Moon and Mercury? -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. -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. -Early in their histories, they suffered many impacts and experienced some volcanism and tectonics, but they now have little geological activity at all.

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 high surface temperature that has "baked out" all the liquid water from Venus's crust and mantle. -The slow rotation of Venus. -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.

What are the two geological features that appear to set Earth apart from all the other terrestrial worlds? -mantle convection and a thick atmosphere -significant volcanism and tectonics -plate tectonics and widespread erosion -shield volcanoes and plate tectonics

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

Why is Earth's continental crust lower in density than seafloor crust? -Continental crust comes from Earth's inner core while seafloor crust comes from the outer core. -Continental crust comes from volcanoes while seafloor crust comes from geysers. -Continental crust is made as the lowest-density seafloor crust melts and erupts to the surface near subduction zones. -Continental crust is made from a low-density volcanic rock called basalt.

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

What's the fundamental reason that Mars, unlike the Earth, has become virtually geologically dead? -its farther distance than Earth to the Sun -its large size compared to the Earth -its rapid rotation compared to the Earth -its slow rotation compared to the Earth -its closer distance than Earth to the Sun -its small size compared to Earth

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 composition -its distance from the Sun

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

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 Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours. -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 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 Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours. -Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days. -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 basketball -a dust speck to a golf ball -a golf ball to a baseball -a golf ball to a beach ball

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

What do we mean when we say that the terrestrial worlds underwent differentiation? -Their surfaces show a variety of different geological features resulting from different geological processes. -They lost interior heat to outer space. -The five terrestrial worlds all started similarly but ended up looking quite different. -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 thin layer of rock that lies between the mantle and crust -a layer of hot, molten rock encompassing the core and part of the mantle -a layer of relatively strong, rigid rock, encompassing the crust and part of the mantle -the interior region in which the planet's magnetic field is generated

The major processes that heat the interiors of the terrestrial worlds are: -(1) Volcanism; (2) tectonics; (3) erosion. -(1) Heat deposited as the planets were built from planetesimals; (2) heat deposited as the planets underwent differentiation; (3) heat released by radioactive decay. -(1) Heat of accretion; (2) heat from convection; (3) heat from thermal radiation. -(1) Heat deposited as the planets were built from planetesimals; (2) heat of accretion; (3) heat that came from the gravitational potential energy of incoming planetesimals.

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

What are the basic requirements for a terrestrial world to have a global magnetic field? -A metal core, a rocky mantle, and sufficiently rapid rotation. -A core layer of molten, convecting material and sufficiently rapid rotation. -A core that has a molten layer and a mantle that has convection. -A metal core and rapid rotation.

In general, which things below are affected by a magnetic field? -Charged particles or magnetized materials (such as iron). -Rocks of all types. -Gases and liquids. -Iron-bearing minerals only.

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

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

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

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

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

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

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

Which of the following does NOT provide evidence that Mars once had abundant liquid water on its surface? -the presence of features that look like dried up river beds -the presence of canali, discovered in the late 1800s by Giovanni Schiaparelli and mapped by Percival Lowell. -the presence of "blueberries" made of the mineral hematite -the presence of very old craters that appear to have been eroded by rain

Based on its surface features, the most important event on Venus in the past billion years or so was _______. -the onset of mantle convection, which caused Venus's lithosphere to split into plates like those on Earth -the eruption of a giant volcano that formed one of Venus's "continents" -a global "repaving" that erased essentially all the surface features that had existed earlier. -the impact of an unusually large asteroid that left a deep scar on one side of the planet

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

How does seafloor crust differ from continental crust? -Seafloor crust is thicker, younger, and lower in density. -Seafloor crust is thicker, older, and higher in density. -Seafloor crust is thinner, younger, and higher in density. -Seafloor crust is thinner, older, and lower in density.

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 slipping sideways against one another. -A place where two plates are pulling apart. -A place where a seafloor plate is sliding under a continental plate.

Which of the following places is the result of volcanoes erupting over a hot spot in the mantle? -the Himalayas -California -the Appalachians -Hawaii

-Mars, because we see dried up riverbeds *Notice the pattern that looks like branches, which is actually lots of small channels feeding into a larger river.*

-an impact crater *It is Meteor Crater in Arizona.*

These four photos show features of Earth that change with time, some fast and some slow. Which one of these features is being shaped primarily by the process we call tectonics?

-1 *The smooth, dark regions are the lunar maria.*

-Valles Marineris *Notice that it is a large canyon stretching almost halfway around Mars.*

-Liquid water still flows occasionally at or near the surface. *The gullies are presumably formed by flowing water, and they must be recent or they would have been erased by winds. (Photos taken a few years apart also show new gullies, providing further evidence of their recent origin.)*

-The yellow color is arbitrary, since this image was created with radar data rather than visible light. *We use radar to study the surface of Venus because we cannot otherwise see through Venus's thick clouds.*

-They represent boundaries between the plates that make up Earth's lithosphere. *And the white arrows indicate directions of plate movement.*

-2 *This is the mid-Atlantic ridge, where mantle material emerges to the ocean floor and spreads out as new seafloor crust.*

-The most important factor in a planet's geological history is its size. *Notice that size is the key factor in volcanism and tectonics. Impacts (show at the top) affect all worlds equally. The only geological process not shown is erosion, but we know that erosion depends on having an atmosphere, which in turn depends on having outgassing from volcanism (and tectonics).*

What important change in the Sun over the past four billion years is thought to be very important to understanding the climates of Venus, Earth, and Mars? -a gradual reduction in the amount of ultraviolet and X-ray radiation coming from the Sun -a gradual brightening with time -a gradual weakening of the solar wind with time -a gradual dimming with time

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

Which of the following best describes the nature and origin of the atmospheres of the Moon and Mercury? -They have very thin atmospheres produced by outgassing but still have the layers of a troposphere, thermosphere, and exosphere. -They have thin exospheres only, with gas coming from impacts of subatomic particles and photons. -They have thin tropospheres only, with gas coming from evaporation and sublimation. -They have only small amounts of gas, all of which is left over from outgassing long ago.

What do we mean by a runaway greenhouse effect? -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 -a greenhouse effect that keeps getting stronger until all of a planet's greenhouse gases are in its atmosphere -a greenhouse effect that starts on a planet but later disappears as gases are lost to space -a greenhouse effect that heats a planet so much that its surface rock melts

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

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

Based on everything we have learned about Venus and Mars, what is the most surprising aspect of Earth's climate history? -the fact that Earth had enough water to form oceans -the fact that Earth apparently got a lot of atmospheric gas from outgassing by volcanoes -the fact that Earth's climate can be affected by changes in its axis tilt -the fact that the temperature of our planet has remained relatively steady throughout our planet's history

Which of the following is NOT an expected consequence of global warming? -an increase in the number and intensity of hurricanes -melting of polar ice and glaciers -warming up of the entire Earth by the same amount -an increase in the severity of winter blizzards

Which planet(s) have an atmosphere that consists mostly of carbon dioxide? -Venus and Mars -Venus, Earth, and Mars -Mars only -Venus only

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

The greenhouse effect occurs in the -troposphere. -stratosphere. -lithosphere.

On a cloudless day, what happens to most of the visible light headed toward Earth? -It is reflected by Earth's atmosphere. -It is absorbed and reemitted by gases in Earth's atmosphere. -It is completely reflected by Earth's surface. -It reaches Earth's surface, where some is reflected and some is absorbed.

On a day with complete cloud cover, what happens to the visible light headed toward Earth? -The clouds reflect much of it back to space, though some still reaches the surface. -It is absorbed by the clouds, which causes the clouds to heat up. -It reaches the surface just as it does on a cloudless day.

What happens to the energy that the ground absorbs in the form of visible sunlight? -It is returned upward in the form of infrared light. -It is returned upward in the form of visible light. -It makes the ground continually get hotter and hotter.

The greenhouse effect raises Earth's surface temperature (from what it would be otherwise) because the infrared light radiated by Earth's surface __________. -travels directly out to space -becomes permanently trapped by greenhouse gases -is temporarily absorbed by greenhouse gases and then reemitted in random directions

What is the leading hypothesis for Venus's lack of water? -Venus formed closer to the Sun and accreted very little water. -Its water is locked away in the crust. -Its water molecules were broken apart, and hydrogen was lost to space.

What kind of gas is most affected by thermal escape? -greenhouse gases -light gases -all gases equally

What causes the release of oxygen into Earth's atmosphere? -outgassing -evaporation/sublimation -photosynthesis

If Earth had as much carbon dioxide in its atmosphere as Venus, our planet would be too hot for liquid water to exist on the surface.

The following images show four types (wavelengths) of light. Rank these from left to right based on the amount of each that is emitted (as thermal radiation) by Earth's surface, from greatest to least. If you think that two (or more) types should be ranked as equal, drag one on top of the other(s) to show this equality.

In Part A, you found that Earth emits only infrared light. This infrared light can be absorbed by greenhouse gases, such as carbon dioxide and water vapor, in the atmosphere. In fact, all the terrestrial planets emit infrared light from their surfaces. The following images show the four terrestrial planets in our solar system. Rank these planets from left to right based on the total amount of infrared-absorbing greenhouse gases in their atmospheres, from greatest to least.

The following images show the four terrestrial planets in our solar system. Rank the planets from left to right based on the strength of the greenhouse effect occurring at their surfaces, from strongest to weakest.

The following images show the four terrestrial planets in our solar system. Rank the planets from left to right based on the amount by which the greenhouse effect increases their surface temperatures, compared to what their temperatures would be without the greenhouse effect, from largest to smallest increase.

The average temperature over the past 1000 years has been about 15∘C. From the graphs, you can conclude that Earth's average temperature during the past 400,000 years has __________. -varied between about −10∘C and +4∘C -stayed remarkable steady, never varying by more than about 2∘C -varied between about 7∘C and 19∘C -never been as high as it is today

On the graphs shown, you can identify an ice age by looking for __________. -a trough (bottom of a dip) on the temperature graph -a place on the temperature graph where the temperature curve falls steeply -a peak on the temperature graph -a trough (bottom of a dip) on the carbon dioxide graph

Notice that the peaks and troughs on the temperature graph occur at the about the same times as peaks and troughs on the carbon dioxide graph. What can we infer from this fact alone? -Higher global average temperatures cause higher carbon dioxide concentrations. -There is a correlation between the carbon dioxide concentration and the global average temperature. -Higher carbon dioxide concentrations cause higher global average temperatures. -The carbon dioxide concentration is inversely related to the global average temperature.

Although the data show only a correlation between the carbon dioxide concentration and the global average temperature, there are other reasons to think that a rise in the carbon dioxide concentration actually causes a rise in the global average temperature. All of the following statements are true. Which statements lend support to the idea that carbon dioxide is a cause of planetary warming? Check all that apply. -Models of the greenhouse effect successfully predict the temperatures of Venus and Mars from their atmospheric carbon dioxide amounts. -We understand the physical mechanism of the greenhouse effect, through which carbon dioxide can increase a planet's temperature. -Isotope ratios in atmospheric carbon dioxide show that much of the carbon dioxide in Earth's atmosphere today comes from the burning of fossil fuels. -Models of Earth's climate that include recent increases in the carbon dioxide concentration match observed temperature increases better than those that do not include it.

Based on the evidence that atmospheric carbon dioxide is a cause of planetary warming, what aspect of the graphs should most concern us? -Earth's past temperature rises and falls naturally. -Earth's past carbon dioxide concentration rises and falls naturally. -The carbon dioxide concentration today is significantly higher than at any time in the past 400,000 years and is rapidly rising.

Make a prediction: If the rise in carbon dioxide concentration continues at its current pace, the concentration in the year 2037 will be about _____ parts per million. -330 -390 -430 -510

The energy that warms Earth's surface comes primarily in the form of __________. -infrared light from the Sun -heat from Earth's interior -ultraviolet light from the Sun -visible light from the Sun -heat from the Sun

Earth's temperature remains fairly steady, which means that Earth must return the same amount of energy to space that it receives from the Sun. In what forms does Earth return most of this energy to space? Check all that apply. -infrared light emitted by the surface and atmosphere -visible light emitted by the surface and atmosphere -ultraviolet light reflected by the surface -visible light reflected by clouds -visible light reflected by the surface

Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, make Earth warmer than it would be otherwise because these gases __________. -reflect visible light coming from the Sun -form clouds that emit thermal radiation -absorb visible light coming from the Sun -absorb infrared light emitted by the surface

According to scientists, the naturally occurring greenhouse effect makes Earth about 31∘C warmer than it would be if there were no greenhouse gases in our atmosphere. How do scientists "know" what Earth's temperature would be without greenhouse gases? -They estimate it by averaging guesses made by many individual scientists. -Ancient fossils allow them to infer Earth's temperature at a time before our atmosphere contained greenhouse gases. -They calculate this temperature from Earth's reflectivity and distance from the Sun. -They assume that this temperature would be about the same as the temperature of Mars, which has much less of an atmosphere than Earth.

All of the following statements are true. Which one provides strong observational support for the claim that greenhouse gases make a planet warmer than it would be otherwise? -Earth is the only planet with an ozone layer in its atmosphere. -Earth has a higher average temperature than Mars. -Venus has a higher average temperature than Mercury. -Mercury is much hotter than the Moon.

Based solely on an understanding of the greenhouse effect (as displayed in the figure), which one of the following statements is true? -Humans are causing global warming. -We do not yet understand the greenhouse effect well enough to make predictions about how it affects our planet. -Global warming poses a grave threat to our future. -We should expect an increase in the greenhouse gas concentration to lead to global warming.

Which terrestrial world has the most atmosphere? -Venus -Earth -Mars

What kind of light warms the stratosphere? -infrared -visible -ultraviolet

Which of the following is a strong greenhouse gas? -nitrogen -water vapor -oxygen

In which direction do hurricanes in the Southern Hemisphere rotate? -clockwise -counterclockwise -either direction

Where is most of the CO2 that has outgassed from Earth's volcanoes? -in the atmosphere -escaped into space -locked up in rocks

Listed following are characteristics of the atmospheres of Venus, Earth, and Mars. Match each atmospheric characteristic to the appropriate planet.

The following images show the four terrestrial planets in our solar system. Rank these planets from left to right based on the atmospheric pressure at the surface, from highest to lowest. (Not to scale.)

The following images show the four terrestrial planets in our solar system. Rank these planets from left to right based on the total amount of gas in their atmospheres, from most to least. (Not to scale.)

1. Most of the charged particles from the Sun are deflected around Earth by the

2. Earth's ________________ absorbs most of the ultraviolet light arriving here from the Sun.

3. Most of the X-rays coming from the Sun are absorbed in the

4. Gas particles in Earth's atmosphere most easily escape from the

5. The densest layer of the atmospheres of Venus, Earth, and Mars is the

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

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 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 -a greenhouse effect that keeps getting stronger until all of a planet's greenhouse gases are in its atmosphere

The greenhouse effect occurs in the -troposphere. -stratosphere. -lithosphere.

Which of the following correctly lists the terrestrial worlds in order from the thickest atmosphere to the thinnest atmosphere? (Note: Mercury and the Moon are considered together in this question.) -Earth, Venus, Mars, Moon/Mercury -Venus, Mars, Moon/Mercury, Earth -Mars, Venus, Earth, Moon/Mercury -Venus, Earth, Mars, Moon/Mercury

Which lists the jovian planets in order of increasing distance from the Sun? -Jupiter, Saturn, Uranus, Pluto -Saturn, Jupiter, Uranus, Neptune -Jupiter, Saturn, Uranus, Neptune

Why does Neptune appear blue and Jupiter red? -Neptune is hotter, which gives bluer thermal emission. -Methane in Neptune's atmosphere absorbs red light. -Neptune's air molecules scatter blue light, much as Earth's atmosphere does.

Why is Jupiter denser than Saturn? -It has a larger proportion of rock and metal. -It has a higher proportion of hydrogen. -Its higher mass and gravity compress its interior.

Some jovian planets give off more energy than they receive because of -fusion in their cores. -tidal heating. -ongoing contraction or differentiation.

Why is Io more volcanically active than our moon? -Io is much larger. -Io has a higher concentration of radioactive elements. -Io has a different internal heat source.

What is unusual about Triton? -It orbits its planet backward. -It does not keep the same face toward its planet. -It is the only moon with its own rings.

Which moon shows evidence of rainfall and erosion by some liquid substance? -Europa -Titan -Ganymede

Each ring particle in the densest part of Saturn's rings collides with another about every 5 hours. If a ring particle survived for the age of the solar system, how many collisions would it undergo?

Saturn's rings -have looked basically the same since they formed along with Saturn. -were created long ago when tidal forces tore apart a large moon. -are continually supplied by impacts between small moons.

The main ingredients of most satellites of the jovian planets are -rock and metal. -hydrogen compound ices. -hydrogen and helium.

Listed following are some of the distinguishing geological characteristics of the moons orbiting Jupiter. Match each characteristic to the appropriate moon.

Io experiences tidal heating primarily because __________. -Io has an unusually elongated shape that makes it look more like an egg than a sphere -Io is made of relatively soft materials that deform quite easily -Io is located very close to Jupiter -Io's elliptical orbit causes the tidal force on Io to vary as it orbits Jupiter

From Part A, Io's elliptical orbit is necessary to its tidal heating. This elliptical orbit, in turn, is a result of the orbital resonance among Io, Europa, and Ganymede. This orbital resonance causes Io to have a more elliptical orbit than it would otherwise, because __________. -Europa and Ganymede always pull on Io from the same direction as Jupiter pulls on Io -all three moons orbit with the same period, staying aligned at all times -Io periodically passes Europa and Ganymede in the same orbital position -Europa and Ganymede are unusually large moons

We cannot see tidal forces or tidal heating; rather, we predict that they must occur based on the orbital characteristics of the moons. What observational evidence confirms that tidal heating is important on Io? -Io's unusual, egg-like shape -active volcanoes on Io -the orbital resonance between Io, Europa, and Ganymede -Io's surprisingly elliptical orbit

The orbital resonance also gives Europa an elliptical orbit, so it also experiences tidal heating. However, Europa experiences less tidal heating than Io, because Europa __________ than Io. -is much smaller -is farther from Jupiter -is more perfectly spherical in shape -contains much more ice

We now know of many Jupiter-size planets around other stars. Suppose that future observations show that one of these planets has two orbiting moons. What additional information, if any, would we need to decide whether these moons experience tidal heating? -We need to know their orbital periods. -We need to know whether either moon is volcanically active. -We need to know whether the planet also has a third moon. -No other information is needed: With two moons, there is sure to be tidal heating. -No other information is needed: With two moons, there is no chance of any tidal heating

Saturn's rings are composed of __________. -gas from the early solar system -a series of solid concentric circles -lots of individual particles of ice and rock -parts of Saturn's upper atmosphere being vented into space

Saturn's rings look bright because __________. -light from the Sun reflects off the material in the rings -the material in the rings is hot and creates its own light -light from Saturn reflects off the material in the rings

Which of the following statements correctly describes the motion of the particles in Saturn's rings? -Particles in all the rings hover motionlessly high above Saturn. -Particles in the inner rings orbit Saturn at a faster speed than particles in the outer rings. -Particles in the inner rings orbit Saturn at a slower speed than particles in the outer rings. -All the particles in the rings orbit Saturn with the same orbital period.

The following images show Earth and the four jovian planets of our solar system. Rank these planets from left to right based on their distance from the Sun, from closest to farthest. (Not to scale.)

The following images show Earth and the four jovian planets of our solar system. Rank these planets from left to right based on their size (average equatorial radius), from smallest to largest. (Not to scale.)

The following images show Earth and the four jovian planets of our solar system. Rank these planets from left to right based on their mass, from lowest to highest. (Not to scale.)

Which of the following statements best describes the general pattern of composition among the four jovian planets? -Jupiter and Saturn have compositions that are fairly different from the compositions of Uranus and Neptune. -All four planets have essentially the same composition. -Jupiter is made mostly of hydrogen and helium, while the other three jovian planets are made mostly of hydrogen compounds. -Jupiter is made mostly of hydrogen, Saturn is made mostly of helium, Uranus is made mostly of hydrogen compounds, and Neptune is made mostly of rock.

Look at the densities of the jovian planets given in Figure 1. Which of the following statements best describes the pattern of jovian planet densities? -The more massive the planet, the lower the density. -Jupiter is the densest, and the densities of the other planets decrease in order of distance from the Sun. -The more massive the planet, the higher the density. -There is no clear trend in the densities. -Jupiter is the densest, and the densities of the other planets increase in order of distance from the Sun.

Which of the following statements best explains why the densities of Uranus and Neptune are higher than those of Jupiter and Saturn? -They have a higher proportion of hydrogen compounds and rock. -They are at greater distances from the Sun. -Their interiors are more compressed due to stronger gravity. -They have higher masses. -They have stronger magnetic fields.

Which of the following best explains why Jupiter's density is higher than Saturn's? -Jupiter is closer to the Sun than Saturn. -Jupiter is more massive than Saturn. -Jupiter has a higher proportion of hydrogen compounds and rock than Saturn. -Jupiter has a stronger magnetic field than Saturn.

Based on the leading scientific theory of solar system formation, which of the following statements best explains why Uranus and Neptune have a significantly different composition and higher density than Jupiter and Saturn? -Jupiter and Saturn captured more gas from the solar nebula than Uranus and Neptune. -The lower temperatures at the locations of Uranus and Neptune allowed more material to condense into solid form into solid form. -The lower masses of Uranus and Neptune allowed more of their hydrogen and helium gas to escape into space. -Jupiter and Saturn formed closer to the Sun, where there was more hydrogen and helium gas and less hydrogen compounds and rock.

What atmospheric constituent is responsible for the blue color of Uranus and Neptune? -methane -ammonia -hydrogen -water

Sort each of the planetary properties below based on whether they apply to some, all, or none of the four jovian planets in our solar system.

The main ingredients of most satellites of the jovian planets are -rock and metal. -hydrogen compound ices. -hydrogen and helium.

Saturn's many moons affect its rings through -tidal forces. -orbital resonances. -magnetic field interactions.

1. The largest moon in the solar system is

2. The jovian moon with the most geologically active surface is

3. Strong evidence both from surface features and magnetic field data support the existence of a subsurface ocean on

4. _________________ is responsible for the tremendous volcanic activity on Io.

5. __________________ is the most distant of Jupiter's four Galilean moons.

6. The fact that Europa orbits Jupiter twice for every one orbit of Ganymede is an example of a(n) ___________________.

Which of the following shows the four jovian planets correctly scaled in size?

Which of the following photos shows the planet Neptune?

-the Great Red Spot *The Great Red Spot is a very large storm, wide enough to swallow two or three Earths.*

-about the same size (radius) as Jupiter *Notice that the curve turns back downward at masses just a couple times that of Jupiter, and the radius of a 10 Jupiter-mass object is about the same as the radius of Jupiter*

-Jupiter's magnetic field *The magnetic field is stronger where the lines are closer together and weaker where they are farther apart.*

-volcanoes on Jupiter's moon Io *Tidal heating makes Io the most volcanically active place in the solar system.*

-Saturn's moon Titan *Notice the fuzzy atmosphere that is clearly visible.*

-Jupiter's moon Europa *Notice the long cracks in the icy surface.*

-It is quite small in size compared to moons that are spherical. *If it were larger, it would be spherical.*

-About a size that you could hold in your arms. *Most of the ring particles are about this size, though there is lots of variation.*

Saturn's rings: -have looked basically the same since they formed along with Saturn. -were created long ago when tidal forces tore apart a large moon. -are continually supplied with new particles by impacts with small moons.

Which of the following is a general characteristic of the four jovian planets in our solar system? -They are lower in average density than are the terrestrial planets. -They are less massive then any of the terrestrial planets. -They have solid surfaces. -They have very little hydrogen, helium, and hydrogen compounds.

What atmospheric constituent is responsible for the blue color of Uranus and Neptune? -water -ammonia -hydrogen -methane

Which statement about Io is true? -It is thought to have a deep, subsurface ocean of liquid water. -It is the most volcanically active body in our solar system. -It is the only moon in the solar system with a thick atmosphere. -It is the largest moon in the solar system.

Which moon is considered likely to have a deep, subsurface ocean of liquid water? -Europa -Triton -Io -Miranda

Suppose you could float in space just a few meters above Saturn's rings. What would you see as you looked down on the rings? -Nothing—up close, the rings would be so completely invisible that you'd have no way to know they are there. They can be seen only from a distance. -dozens of large "moonlets" made of metal and rock, each a few kilometers across -a solid, shiny surface, looking much like a piece of a DVD but a lot bigger -countless icy particles, ranging in size from dust grains to large boulders

Which moon has a thick atmosphere made mostly of nitrogen? -Triton -Ganymede -Titan -Europa

Which of the following statements about the moons of the jovian planets is NOT true? -Some of the moons are big enough that we'd call them planets (or dwarf planets) if they orbited the Sun. -Many of the moons are made largely of ices. -Most of the moons are large enough to be spherical in shape, but a few have the more potato-like shapes of asteroids. -One of the moons has a thick atmosphere.

Which of the following best describes the internal layering of Jupiter, from the center outward? -solid rock core; layer of solid metallic hydrogen; layer of pure liquid hydrogen; cloud layer -liquid core of hydrogen compounds; liquid hydrogen layer; metallic hydrogen layer; gaseous hydrogen layer; cloud layer -core of rock, metal, and hydrogen compounds; thick layer of metallic hydrogen; layer of liquid hydrogen; layer of gaseous hydrogen; cloud layer -core of rock and metal; mantle of lower density rock; upper layer of gaseous hydrogen; cloud layer

Overall, Jupiter's composition is most like that of _________. -the Sun -a comet -Earth -an asteroid

How do typical wind speeds in Jupiter's atmosphere compare to typical wind speeds on Earth? -They are slightly slower than average winds on Earth. -They are about the same as average winds on Earth. -They are much faster than hurricane winds on Earth. -They are slightly faster than average winds on Earth.

HOMEWORK 11

According to Figure 12.25, the odds of a 100-meter asteroid hitting Earth over the course of one year is approximately __________. -somewhat less than 1 in 100 -That information cannot be inferred from the figure, which only reports typical time between impacts. -about 1 in 1,000,000 -somewhat less than 1 in 1000

According to current evidence, Pluto is best explained as ______. -an escaped moon of Jupiter or Saturn -a terrestrial planet that is surprisingly far from the Sun -a large member of the Kuiper belt -a very small jovian planet

Which direction do a comet's dust and plasma tails point? -generally away from the Sun -straight behind the comet in its orbit -always almost due north -perpendicular to the ecliptic plane

A typical meteor is created by a particle about the size of a _________. -baseball -pea -basketball -car

A rock found on Earth that crashed down from space is called _________. -a meteorite -an impact -a meteor -an asteroid

The asteroid belt is located _________. -between the orbits of Earth and Mars -between the orbits of Mars and Jupiter -beyond the orbit of Neptune -between the orbits of Jupiter and Saturn

Among discovered meteorites, we have found some with all the following origins EXCEPT _________. -being a fragment from the surface of the Moon -being a fragment of a shattered asteroid -being a fragment from the surface of Mars -being a fragment from Comet Halley

Which statement is NOT thought to be true of all comets in our solar system? -Comets always have tails. -All comets orbit the Sun. -All comets are icy in composition. -All comets are leftover planetesimals that originally condensed beyond the frost line in the solar nebula.

When a comet passes near the Sun, part of it takes on the appearance of a large, bright ball from which the tail extends. This part is called _________. -the nucleus -the plasma tail -the Oort core -the coma

Which of the following statements about asteroids, Kuiper belt objects, and Oort cloud objects is true? -Objects in the asteroid belt are made mostly of ice. -Objects in the asteroid belt and Kuiper belt orbit the Sun in nearly the same plane as the planets, but objects in the Oort cloud do not. -Objects in the Oort cloud are made mostly of rock and metal. -Objects in the Kuiper belt are made mostly of rock and metal.

Jupiter nudges the asteroids through the influence of -tidal forces. -orbital resonances. -magnetic fields.

Did a large terrestrial planet ever form in the region of the asteroid belt? -No, because there was never enough mass there. -No, because Jupiter prevented one from accreting. -Yes, but it was shattered by a giant impact.

How big an object causes a typical shooting star? -a grain of sand or a small pebble -a boulder -an object the size of a car

Listed following are some distinguishing characteristics of comets, meteors, and asteroids. Match these to the appropriate category of objects.

Listed following are several objects in the solar system. Rank these objects from left to right based on their distance from the Sun, from closest to farthest.

Listed following are several objects in the solar system. Rank these objects from left to right based on their orbital period around the Sun from shortest to longest.

Listed following are several objects in the solar system. Rank these objects from left to right based on the distance from the Sun at which they are presumed to have formed, from nearest to farthest.

The following figures show four positions (1-4) of a comet during its orbit of the Sun. Also shown is the orbit of the Earth around the Sun. Rank the positions of the comet from left to right based on the size of its tail, from shortest to longest. (Not to scale; tails not shown.)

A few hundred tons of comet dust gets added to Earth daily from the millions of meteors that enter our atmosphere. Estimate the time it would take for Earth to get 0.1% heavier at this rate. -10^10 years -10^14 years -10^18 years -10^20 years

A few hundred tons of comet dust gets added to Earth daily from the millions of meteors that enter our atmosphere. Is this mass accumulation significant for Earth as a planet?

A comet entering the inner solar system from afar will __________. -form a tail and some time later form a coma. -form a coma and some time later form a tail -always form a tail, but only sometimes form a coma

During the time that a comet passes through the inner solar system, the comet can appear quite bright because __________. -heat from the Sun causes the comet's nucleus to glow -increasing friction causes the comet's nucleus to glow -sunlight reflects off the comet's tail and coma -sunlight reflects off the comet's nucleus

A comet's plasma tail always points directly away from the Sun because __________. -of pressure exerted by the fast-moving charged particles in the solar wind -centrifugal forces throw the tail outward as the comet travels around the Sun -the comet's nucleus overheats on the Sun-facing side, forcing energetic jets of gas to shoot out from the dark side -the tail is left behind as the comet moves through its orbit

Which are thought to have formed farthest from the Sun? -asteroids -Kuiper belt comets -Oort cloud comets

What does Pluto most resemble? -a terrestrial planet -a jovian planet -a comet

Which have the most elliptical and tilted orbits? -asteroids -Kuiper belt comets -Oort cloud comets

The minimum size of an object that could cause a mass extinction is a little less than _____. -10m -100m -1km -10km -10 km

An object 10 kilometers across hits Earth __________. -about once every 1 million years -about once every 100 million years -about once every 1 billion years -just once in Earth's history

What is the probability that an object 100 meters in diameter will hit Earth during the coming year? -about 1 in 2 -about 1 in 10 -about 1 in 1000 -about 1 in 100 million -zero

Which statement below most accurately describes the impacts we should expect on Earth during the coming year? -Earth will be hit by one object about 100 meters in diameter and several objects of about 10 meters in diameter. -Earth will be hit by at least one object a few meters in diameter, along with many smaller objects. -Earth will be hit by one object that is a few meters in diameter, but no larger or smaller objects. -Only objects smaller than 1 meter across will hit Earth.

The impact of a 100-meter object will not cause "widespread" devastation, but it could still kill millions of people if it struck a major city. In Part C, you found that the probability of such an impact in any single year is only 1 in 1000. Suppose we learn that it has already been 1200 years since the last such impact. What would that tell us? -Nothing; we would still presume that the chance of such an impact during the next year is 1 in 1000. -We are overdue for the impact of a 100-meter object, so we should expect the impact of an even larger object during the next few years. -There must be something wrong with the graph, because if the 1 in 1000 probability were correct, then there would have been an impact some time during the past 1000 years. Since there wasn't, the actual probability must be lower than 1 in 1000. -We are clearly due for such an impact, so the actual probability for the coming year must be much higher than 1 in 1000.

About how often does a 1-kilometer object strike Earth? -every year -every million years -every billion years

What would happen if a 1-kilometer object struck Earth? -It would break up in the atmosphere without causing widespread damage. -It would cause widespread devastation and climate change. -It would cause a mass extinction.

The asteroid belt lies between the orbits of -Earth and Mars. -Mars and Jupiter. -Jupiter and Saturn.

Can an asteroid be pure metal? -No, all asteroids contain rock. -Yes, it must have formed where only metal could condense in the solar nebula. -Yes, it must have been the core of a shattered asteroid.

1. About a trillion comets are thought to be located far, far beyond Pluto in the

2. The bright spherical part of a comet observed when it is close to the Sun is the

3. A comet's _________________ stretches directly away from the Sun.

4. A comet's _________________ is the frozen portion of a comet.

5. Particles ejected from a comet can cause a(n) ________________________ on Earth.

6. The ____________________ extends from about beyond the orbit of Neptune to about twice the distance of Neptune from the Sun.

Which photo shows an object that looks most like a typical asteroid?

-the asteroid belt *As shown, the asteroid belt lies between the orbits of Mars and Jupiter.*

-There are few if any asteroids at the indicated orbital period of about 4 years. *The gap means few asteroids, and notice this is at an orbital period of 4 years.*

-It would have looked virtually the same. *A comet does not move noticeably through our sky in a matter of minutes. In fact, the comet will still be in nearly the same place relative to the stars for many days, because it is quite far away and therefore moves slowly through our sky.*

A comet grows tails (plasma tail and dust tail) when it comes close to the Sun. Which of the following diagrams shows a comet's tails correctly oriented as they appear along its orbit?

-the Kuiper belt *As shown, the Kuiper belt lies in the region just beyond Neptune's orbit.*

What of the following sketches shows the dwarf planets Pluto and Eris correctly scaled in comparison to Earth?

Pluto looks much like one of the following objects. Which one?

-every day *But nearly all of these objects burn up in the atmosphere and therefore do not hit the ground.*

-about once every 50 million years *These are rare events, but they have had a profound effect on Earth's biological history.*

Which of the following statements is not true? -Objects in the Oort cloud contain large proportions of ice. -Objects in the asteroid belt are made mostly of rock and metal. -Objects in the Kuiper belt are made mostly of rock and metal. -Objects in the asteroid belt and Kuiper belt orbit the Sun in nearly the same plane as the planets, but objects in the Oort cloud do not.

A rock found on Earth that crashed down from space is called ______. -an impact -a meteor -an asteroid -a meteorite

The asteroid belt is located ______. -beyond the orbit of Neptune -between the orbits of Earth and Mars -between the orbits of Mars and Jupiter -between the orbits of Jupiter and Saturn

Which statement about asteroids is not true? -Many but not all orbit the Sun in the asteroid belt. -Some are more like loosely bound piles of rubble than solid chunks of rock. -Most asteroids are not spherical in shape. -If we could put all the asteroids together, they would make an object about the size of Earth.

A typical meteor is created by a particle about the size of a _________. -basketball -pea -baseball -car

What do we mean by a primitive meteorite? -a meteorite that was discovered by primitive people -a meteorite that fell to Earth at least 4 billion years ago -a type of meteorite that is usually made mostly of high-density metals -a meteorite that is essentially unchanged since it first condensed and accreted in the solar nebula some 4.6 billion years ago

Among discovered meteorites, we have found some with all the following origins except _________. -being a fragment from the surface of Mars -being a fragment from Comet Halley -being a fragment from the surface of the Moon -being a fragment of a shattered asteroid

Which statement is not thought to be true of all comets in our solar system? -Comets always have tails. -All comets orbit the Sun. -All comets are icy in composition. -All comets are leftover planetesimals that originally condensed beyond the frost line in the solar nebula.

Which direction do a comet's dust and plasma tails point? -generally away from the Sun -perpendicular to the ecliptic plane -always almost due north -straight behind the comet in its orbit

When a comet passes near the Sun, part of it takes on the appearance of a large, bright ball from which the tail extends. This part is called _____. -the plasma tail -the Oort core -the coma -the nucleus

The total number of comets orbiting the Sun is estimated to be about ______. -100,000 -1 trillion -1,000 -1 million

Halley's comet is named after the English scientist Edmund Halley (1656--1742) because ______. -he was the first person to see it when it passed near Earth in 1682. -it was in honor of his financial support. -he was the most famous astronomer alive in England during its appearance in 1758. -he calculated its orbit and predicted the year in which it would next be seen.

What is Charon? -A captured moon of Neptune -The largest of Pluto's three known moons -The largest known Kuiper belt comet -The largest known asteroid

According to current evidence, Pluto is best explained as ______. -a large member of the Kuiper belt -an escaped moon of Jupiter or Saturn -a very small jovian planet -a terrestrial planet that is surprisingly far from the Sun

What is Eris? -The largest known asteroid. -A moon of Pluto. -An icy object that orbits in the Kuiper belt and is larger than Pluto -An extrasolar planet ejected by another solar system and captured by ours.

What was the Shoemaker-Levy 9 impact? -the impact thought to have wiped out the dinosaurs -the ninth impact witnessed by astronomers in modern times -the 1994 impact of a chain of comet fragments into Jupiter -the impact that created the Moon's largest crater

What do we mean by a mass extinction? -the extinction of a large fraction of the world's plant and animal species in a relatively short period of time -the extinction of large animals, such as dinosaurs -the extinction of any species of plant or animal that has mass -an extinction caused by the impact of an asteroid or comet

If the hypothesis tracing the extinction of the dinosaurs to an impact is correct, the dinosaurs died off largely because ______. -the impact caused massive earthquakes worldwide -of global climate effects initiated by dust and smoke that entered the atmosphere after the impact -of injuries suffered from direct hits of pieces of the asteroid or comet -radiation from iridium in the asteroid caused the dinosaurs to die of cancer