Earth and Terrestrial Planets

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

1

A planet is most likely to have tectonic activity if it has high internal temperature. high surface gravity. low internal temperature. a dense atmosphere. low surface gravity.

1

A terrestrial world's lithosphere is ________. 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 a layer of hot, molten rock encompassing the core and part of the mantle the interior region in which the planet's magnetic field is generated

1

Where is most of the water on Mars? in frozen lakes and oceans on its surface distributed evenly throughout its atmosphere in its clouds frozen on the peaks of its tall volcanoes in its polar caps and subsurface ground ice

5

As you found in Part A, early Mars had both core convection and a strong magnetosphere. What is the connection between these two things? Core convection helps generate a magnetic field, and the magnetic field creates the magnetosphere. Core convection creates volcanism and outgassing, the gas creates the magnetosphere. Both core convection and a magnetosphere are consequences of a strong greenhouse effect. Both core convection and a magnetosphere can exist only a very young planet.

1

Earth has a relatively strong magnetic field, but Mars does not. Which of the following probably explains why Mars lacks a strong magnetic field today? Its core is too cool for convection. Its lithosphere is too thick. It is too far from the Sun. It rotates too slowly.

1

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

1

How have we been able to construct detailed maps of surface features on Venus? by using radar from spacecraft that were sent to orbit Venus by studying Venus from Earth with powerful telescopes by studying Venus with powerful telescopes on spacecraft that were sent to orbit Venus by making computer models of geological processes on Venus by landing spacecraft on the surface for close-up study

1

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 the evaporation of water that adds water vapor (a gas) to an atmosphere another name for a volcanic eruption the loss of atmospheric gas to outer space

1

Its rotation is too slow. It is too close to the Sun. It is too large. It does not have a molten metallic outer core. Its atmosphere is too thick.

1

Rank the five terrestrial worlds in order of size from smallest to largest. Moon, Mercury, Mars, Venus, Earth Mercury, Venus, Earth, Moon, Mars Mercury, Moon, Venus, Earth, Mars Moon, Mercury, Venus, Earth, Mars Mercury, Moon, Mars, Earth, Venus

1

Scientists can estimate the age of a planetary surface by counting __________. impact craters tectonic features erosion features volcanoes

1

The atmospheres of Venus and Mars are primarily composed of carbon dioxide. Why is the surface of Venus so much hotter than the surface of Mars? Venus' atmosphere is thousands of times thicker than Mars' atmosphere. Carbon dioxide on Venus behaves differently than it does on Mars. The clouds of Venus are composed of sulphuric acid, which traps more heat. Venus is much closer to the sun than Mars.

1

The processes responsible for all surface geology on the terrestrial planets are ________. impact cratering, volcanisms, tectonics, and erosion eruptions, lava flows, and outgassing accretion, differentiation, and radioactive decay convection, conduction, and radiation

1

There are no auroras on Venus because it lacks a strong magnetic field. is too hot. lacks strong winds. lacks atmospheric oxygen.

1

Volcanism is more likely on a planet that has high internal temperatures. is struck often by meteors and solar system debris. is closer to the Sun. doesn't have an atmosphere or oceans.

1

What are the two geological features that appear to set Earth apart from other terrestrial worlds in our solar system? View Available Hint(s) Plate tectonics and a high level of erosion A dense core and plate tectonics Significant volcanism and tectonics Mantle convection and a thick atmosphere

1

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. 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. They lost interior heat to outer space.

1

What is the primary message of the full graph (with all three curves shown)? Climate models successfully reproduce the major recent trend in temperature data only if both human and natural factors are included. Climate models can successfully reproduce the major recent trends in temperature data by considering natural factors alone. Climate models are unable to account for the major recent trend in temperature data.

1

Which of the following best describes how the greenhouse effect works? View Available Hint(s) 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. 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 X-rays and ultraviolet light from the Sun, and this absorbed radiation then heats the atmosphere and the surface. Greenhouse gases absorb infrared light coming from the Sun, and this absorbed sunlight heats the lower atmosphere and the surface.

1

Which of the following best describes impact cratering? the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface the eruption of molten rock from a planet's interior to its surface the disruption of a planet's lithosphere by internal stresses the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather

1

Which of the following best describes the geological histories of the Moon and Mercury? View Available Hint(s) Early in their histories, they suffered many impacts and experienced some volcanism and tectonics, but they now have little geological activity at all. Impact cratering is the only major geological process that has affected their surfaces. All four geological processes were important in their early histories, but only impact cratering still reshapes their surfaces today. 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.

1

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

1

Which of the following best explain what we think happened to outgassed water vapor on Venus? View Available Hint(s) 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.

1

Which of the following correctly lists two key pieces of evidence that, together, indicate that we should expect human activity to cause global warming? View Available Hint(s) (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) We can learn about past climate from ice cores; (2) ice cores show that Earth naturally has cooler and warmer periods. (1) The carbon dioxide cycle regulates Earth's climate; (2) human activity has disrupted the carbon dioxide cycle.

1

Which of the following is the main reason why Venus has so little wind erosion? its slow rotation its relatively close distance from the Sun its thick atmosphere its small size

1

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

1

Which of the following statements are supported by the data shown? Earth's global average temperature has generally risen over the past century. Earth's global temperature today is higher than it has ever been before. Atmospheric carbon dioxide levels have risen dramatically over the past century. Human activity has caused the carbon dioxide concentration to swing up and down wildly over the past 800,000 years. Rises in global average temperature tend to be closely associated with rises in atmospheric carbon dioxide concentration.

1 3 5

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

1, 3, 5

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? View Available Hint(s) 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 estimate it by averaging guesses made by many individual scientists. They assume that this temperature would be about the same as the temperature of Mars, which has much less of an atmosphere than Earth.

2

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? View Available Hint(s) Mercury is much hotter than the Moon. Venus has a higher average temperature than Mercury. Earth is the only planet with an ozone layer in its atmosphere. Earth has a higher average temperature than Mars.

2

How does the amount of heat released in a planet's interior by radioactive decay change with time? It increases with time. It drops off with time. It stays constant at all times.

2

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

2

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

2

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? View Available Hint(s) A rapid, up and down churning of the material in the mantle Not much; on human time scales, the mantle looks like solid rock. Hot molten rock rising upward throughout the mantle and cool, solid rock falling downward Dense metals falling downward while low-density rock rises upward

2

The cores of the terrestrial worlds are made mostly of metal because ______. View Available Hint(s) 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 the core contained lots of radioactive elements that decayed into metals over billions of years, convection gradually brought dense metals downward to the core

2

The existence of a core-mantle-crust interior structure tells us that a world __________. View Available Hint(s) is undergoing interior convection once had a molten interior formed initially from metal, around which rock was later added has a molten interior today

2

What key process underlies why Mars changed so much from its early conditions to its conditions today? Slowing of its rotation rate. Interior cooling. Evaporation of its ocean. Outgassing.

2

What makes us think that Mars must once have had an atmosphere that was warmer and thicker? 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 tells us that Mars must once have been much warmer. We think it for purely theoretical reasons, based on calculations showing that the Sun has brightened with time.

2

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

2

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

2

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

2

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

2

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

2

Which of the following occur as the greenhouse gas concentration increase? Select all that apply. the average surface temperature falls more infrared light is absorbed in the lower atmosphere less visible light reaches the ground the average surface temperature rises more infrared light comes to Earth from the Sun more visible light reaches the ground more visible light is absorbed in the lower atmosphere

2, 4

Which of the following statements about our solar system's terrestrial worlds are true? View Available Hint(s) They all have active volcanoes. Their interiors all have a core, mantle, and crust. They are all of nearly the same age. They all have surfaces that are heavily cratered today. They all have lithospheres that extend almost all the way to their cores. They are all made primarily of rock and metal.

2,3,6

According to current climate models and given the current emission rate of carbon dioxide, how much will the Earth's average temperature increase by the end of this century? 0°C 0-2°C 2-5°C 5-7°C 7-10°C

3

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

3

As a general rule, smaller planets __________ than larger planets. rotate faster have larger cores cool more rapidly have stronger magnetic fields rotate slower

3

As discussed in the video, the leading hypothesis for why Mars changed holds that interior cooling led to loss of its magnetosphere, allowing the solar wind to strip atmospheric gas away. How has the MAVEN mission provided evidence for this hypothesis? It has measured the strength of the magnetic field that Mars had long ago. It has measured the rate at which Mars's interior has lost heat. It has measured rates of gas loss from the atmosphere today. It measured the amount of atmospheric gas that Mars had long ago.

3

How does Earth's magnetosphere affect our atmosphere? It produces chemical reactions that cause ozone to form in the upper atmosphere. It scatters the shorter wavelengths of light from the sun and causes the sky to be blue. It deflects solar wind particles that would otherwise strip away the atmosphere. all of the above

3

Mars' atmosphere is mostly carbon dioxide. Why does it not experience a runaway greenhouse effect like Venus? Mars does not have enough additional water to magnify the warming. Mars is protected by its magnetic field. Mars' atmosphere is too thin.

3

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? View Available Hint(s) 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.

3

Sunsets and sunrises often appear red because the Sun emits more red light when it's rising and setting. sunlight must pass through more atmosphere, which scatters the longer wavelengths more than the shorter wavelengths, allowing more red light to reach your eye. sunlight must pass through more atmosphere, which scatters the shorter wavelengths more than the longer wavelengths, allowing more red light to reach your eye. the cooler atmosphere in the morning and evening absorbs more blue light. none of the above

3

Suppose Earth were to cool down a little. How would the carbon dioxide cycle tend to restore temperatures to normal? View Available Hint(s) 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 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. Cooler temperatures allow carbon dioxide to form rain and rain out of the atmosphere.

3

The choices that follow 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.) View Available Hint(s) 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. 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.

3

The choices that follow 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.) View Available Hint(s) 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. Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours.

3

The total CO2 concentration of the atmosphere has increased by about ________ since 1750. Refer to the figure above. 2.5 % 250% 25% None. It has decreased.

3

The two most important processes in heating the interiors of the terrestrial worlds are ________. (1) heat generated by accretion during the process of formation; (2) heat that came from the gravitational potential energy of incoming planetesimals (1) volcanism; (2) heat from radioactive decay (1) heat generated by accretion during the process of formation; (2) heat released by radioactive decay (1) heat from radioactive decay; (2) heat from thermal radiation

3

What makes us think that Mars must once have had an atmosphere that was warmer and had higher surface pressure? View Available Hint(s) The fact that parts of Mars have a lot of craters tell us that Mars must once have been much warmer. We think it for purely theoretical reasons, based on calculations showing that the Sun has brightened with time. 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 presence of inactive volcanoes on Mars tells us that there must once have been a lot of outgassing, and hence a thicker atmosphere.

3

Which of the following gases best absorbs ultraviolet light? carbon dioxide hydrogen ozone nitrogen oxygen

3

Which of the following is the most basic definition of a greenhouse gas? a gas that absorbs visible light a gas that keeps warm air from rising, and therefore warms the surface a gas that absorbs infrared light a gas that reflects infrared light

3

Which of the following planets has the thinnest atmosphere? Earth Venus Mars

3

Which two factors are critical to the existence of the carbon dioxide (CO2) cycle on Earth? View Available Hint(s) Life and active volcanism Active volcanism and active tectonics Plate tectonics and liquid water oceans Life and atmospheric oxygen

3

Why does the burning of fossil fuels increase the greenhouse effect on Earth? Burning produces infrared light, which is then trapped by existing greenhouse gases. Burning fuel warms the planet. Burning releases carbon dioxide into the atmosphere. Burning depletes the amount of ozone, thereby warming the planet.

3

Why is Mars red? The red color of Mars is a result of the scattering of light in the Martian sky. The red color is caused by water ice chemically bound in surface rock. Chemical reactions between surface rock and atmospheric oxygen literally rusted the surface. Martian volcanoes released a much redder lava than volcanoes on Earth.

3

The greenhouse effect makes Earth warmer than it would be otherwise by about 15 K. 30 K. -16 K. There is no greenhouse effect.

30k

All of the following statements are true. Which one explains why Mars has lost so much more interior heat than Earth. Mars has lost much more atmospheric gas than Earth. Mars lacks a large moon. Mars has a much weaker greenhouse effect than Earth. Mars is smaller than Earth. Mars is farther from the Sun than Earth.

4

All the following statements about Venus are true. Which one offers evidence of a global repaving about a billion years ago? View Available Hint(s) 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. 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.

4

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

4

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

4

Many scientists suspect that Venus has a stronger and thicker lithosphere than Earth. If this is true, which of the following could explain it? View Available Hint(s) The smaller size of Venus, which has allowed it to lose much more internal heat than Earth The slow rotation of Venus 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

4

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

4

Of the four gases CO2, H2O, N2, and O2, which are greenhouse gases? all four only CO2 all except O2 CO2 and H2O CO2 and N2

4

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

4

Spacecraft have landed on all the terrestrial worlds except Mars. Venus. Moon. Mercury.

4

The choices that follow 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.) View Available Hint(s) Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 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. Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours.

4

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

4

What are the conditions necessary for a terrestrial planet to have a strong magnetic field? a rocky mantle only fast rotation only a molten metallic core only both a molten metallic core and reasonably fast rotation both a molten metallic core and a rocky mantle

4

Which of the following general statements about Earth's atmosphere is not true? View Available Hint(s) 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.

4

Which of the following is an example of convection? ice floating on a frozen lake rocks sinking in water different kinds of material separating by density, like oil and water warm air expanding and rising while cooler air contracts and falls

4

Why are there fewer large impact craters on the Earth's seafloor than on the continents? View Available Hint(s) The oceans slow large impactors and prevent them from making craters. Most impacts occur on the land. 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.

4

Why does Earth have the strongest magnetic field among the terrestrial worlds? It rotates much faster than any other terrestrial world. It is by far the largest terrestrial world. It is the only one that has a molten metallic outer core. It is the only one that has both a molten metallic outer core and reasonably rapid rotation. It is the most volcanically active world.

4

Why would the weather become more severe as the greenhouse effect increased? Warming would dry out the atmosphere, leading to severe droughts. Warming would reduce the amount of water on the Earth. Warming would deplete the ozone layer and let in more particles from the solar wind. Warming would increase the evaporation of the oceans, leading to more water in the atmosphere and more frequent and severe storms. all of the above

4

How did the lunar maria form? The giant impact that created the Moon left smooth areas that we call the maria. The maria are the result of gradual erosion by micrometeorites striking the Moon. The early bombardment created heat that melted the lunar surface in the regions of the maria. Volatiles escaping from the Moon's interior heated and eroded the surface in the regions of the maria. Large impacts fractured the Moon's lithosphere, allowing lava to fill the impact basins.

5

Suppose Earth's atmosphere had no greenhouse gases. This would cause Earth's average surface temperature to be at the boiling point of water. the same temperature as it is now. slightly warmer than it is now. at the freezing point of water. well below the freezing point of water.

5

What kind of surface features may result from tectonics? mountains volcanos valleys cliffs all of the above

all

Which of the terrestrial worlds has the strongest magnetic field? the Moon Mercury Mars Venus Earth

earth

The terrestrial planet cores contain mostly metal because the entire planets are made mostly of metal. radioactivity created metals in the core from the decay of uranium. metals condensed first in the solar nebula and the rocks then accreted around them. convection carried the metals to the core. metals sank to the center during a time when the interiors were molten throughout.

last

Which terrestrial planet would have its surface temperature the most dramatically changed if its greenhouse gases were removed from its atmosphere? Earth Venus Mars Mercury

venus

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

visible light from the Sun