Deck 10: The Nature and Evolution of Habitability

Question 1

The possible habitability of Mars today is mostly determined by

A) the amount of heat it receives from the Sun
B) the composition of its atmosphere
C) the thickness of its atmosphere
D) geological conditions existing beneath its surface

Answer 1

geological conditions existing beneath its surface

Question 2

The clouds of sulfuric acid present in the venusian atmosphere probably result from

A) the chemical reaction of sulfur dioxide produced by outgassing volcanoes and water
B) the chemical reaction of sulfur dioxide produced by outgassing volcanoes and surface rocks
C) the direct outgassing by volcanoes
D) the boiling of sulfuric acid at the surface

Answer 2

the chemical reaction of sulfur dioxide produced by outgassing volcanoes and water

Question 3

Observations by the Venus Express orbiter have shown

A) the presence of an actively erupting volcano on the surface
B) that the volcanoes on Venus have been extinct for billions of years
C) that lava covered most of the surface of the planet around 750 million years ago
D) evidence for recent volcanic lava flows occurring within the last 250,000 years

Answer 3

evidence for recent volcanic lava flows occurring within the last 250,000 years

Question 4

Evidence for the loss of water from the atmosphere of Venus via the action of ultraviolet light comes from the

A) observation of auroras high in the Venusian atmosphere caused by the action of ultraviolet light on water molecules
B) fact that today, water is found only in the upper atmosphere of Venus
C) observation of an ozone layer in the atmosphere which is formed from the breakup of water molecules by ultraviolet radiation
D) observation of an excess of heavy hydrogen (deuterium) atoms in the atmosphere which are less easily able to escape once the water is broken apart

Question 5

Most of the water that used to be present in the Venusian atmosphere

A) was destroyed in the atmosphere by ultraviolet light from the Sun
B) became chemically incorporated into rocks in the crust
C) was blasted into space by impacts
D) escaped into space

Question 6

Venus is located

A) near the outer border of the Sun's Habitable zone
B) within the Sun's habitable zone
C) near the outer border of the Sun's habitable zone
D) outside the Sun's habitable zone

Question 7

If life is present on Venus today, it will most likely be

A) inside large rocks that are protected from the heat
B) found in the atmosphere where droplets of water can be found
C) endoliths living beneath the crust where liquid water may still be present
D) hyperthermaphiles found on the surface

Question 8

Apart from its distance from its parent star, what is the next most important factor that determines a planet's habitability?

A) whether it has a large moon
B) the size of the planet
C) the chemical composition of its atmosphere
D) the chemical composition of its surface

Question 9

What is the definition of a star's habitable zone?

A) the range of distances from the star where planets with life have been detected
B) the range of distances from the star where rocky planets can form
C) the range of distances from the star where organic molecules can be stable on the surface of a suitable planet
D) the range of distances from the star where liquid water can be stable on the surface of a suitable planet

Question 10

Most of the carbon dioxide on Venus

A) is trapped beneath the surface of the planet in gaseous form
B) has escaped into space
C) is present in its atmosphere
D) is locked up in carbonate rocks in its crust

Question 11

Around 4 billion years ago Venus could have been more Earth-like with liquid water on its surface because

A) Venus has a protective magnetic field
B) its atmosphere was thinner
C) Venus was farther from the Sun
D) the Sun was dimmer so Venus would have received less radiation

Question 12

Based solely on its distance from the Sun, we would expect the surface of Venus to be

A) much hotter than the Earth such that liquid water would only exist as a vapor in the atmosphere
B) much colder than the Earth such that liquid water would freeze
C) hotter than the Earth but not so hot that liquid water could not exist
D) at the same temperature as the Earth with oceans of liquid water

Question 13

If the Earth were to be moved to where Venus is today,

A) the oceans would evaporate, blocking light from the Sun and causing global temperatures to fall
B) carbon dioxide would be released from the oceans leading to higher temperatures but liquid water could still exist on the surface
C) the oceans would evaporate slightly producing a slightly warmer, more humid planet
D) the oceans would evaporate and carbonate rocks would decompose producing a runaway greenhouse effect much more severe than the one that exists on Venus today

Question 14

Over time the Sun's habitable zone has

A) narrowed and moved away from the Sun
B) narrowed and moved closer to the Sun
C) widened and moved closer to the Sun
D) widened and moved away from the Sun

Question 15

The Moon is in the habitable zone of the Sun at the same distance as the Earth but is not habitable. How can this be?

A) the Moon did have water on its surface in the past, but it was destroyed by high-energy particles from the Sun
B) the Moon has never had water on its surface at any time
C) the Moon is too small to retain an atmosphere necessary for liquid water to be stable
D) the Moon did have water on its surface in the past, but it was blasted off the surface by impacts

Question 16

Most of the carbon dioxide on the Earth

A) is locked up in carbonate rocks in its crust or is dissolved in the oceans
B) is trapped beneath the surface of the planet in gaseous form
C) has escaped into space
D) is located in its atmosphere

Question 17

What is the name of the Japanese orbiter sent to Venus in 2010?

A) Hayabusa
B) Benihana
C) Akatsuki
D) Viinasu

Question 18

Europa is located outside the Sun's habitable zone and yet may be habitable. How can this be?

A) Europa's subsurface ocean contains lots of minerals that allow water to remain liquid at much lower temperatures
B) Europa is continually being hit by comets and asteroids which keeps water beneath its surface liquid
C) Europa is tidally heated, allowing liquid water to exist beneath its icy surface
D) Europa is large enough to have appreciable heat trapped inside it to keep water beneath the surface liquid

Question 19

Which of the following statements regarding the determination of surface habitability and subsurface habitability of a planet is correct?

A) both surface and subsurface habitability can be determined only from robotic space probes
B) surface habitability can be determined remotely by studying reflected starlight from a planet, while determining subsurface habitability would require a robotic space probe
C) both surface and subsurface habitability can be determined by analyzing reflected starlight
D) subsurface habitability can be determined remotely by studying reflected starlight from a planet, while determining surface habitability would require a robotic space probe

Question 20

Unlike the Earth, Venus does not have a protective magnetic field because

A) of its proximity to the Sun
B) of its slow rotation
C) it lacks a partially molten iron core
D) there is less magnetized iron on its surface

Question 21

Why does the Sun brighten with time?

A) as time progresses, helium starts to fuse in the core, in addition to hydrogen, leading to an increase in brightness
B) as hydrogen is converted into helium in the core, the number of hydrogen nuclei decreases, decreasing the fusion rate. To maintain the balance with gravity pressing inward, the core compensates by shrinking and heating up
C) as time progresses, more and more heat is trapped inside the core, leading to an increase in brightness
D) as hydrogen is converted into helium in the core, the number of hydrogen nuclei decreases, decreasing the fusion rate. To maintain the balance with gravity pressing inward, the core compensates by expanding and cooling

Question 22

Even though low luminosity stars have narrow habitable zones and hence are less likely to have planets within these zones, they make up for this shortcoming by virtue of the fact that

A) they are very common
B) they have very long lifetimes
C) planets are much more likely to form around them
D) planets around these stars can only form in their habitable zones

Question 23

A star less luminous than our Sun will have a habitable zone that is

A) narrower and closer to the star than the habitable zone of the Sun
B) wider and closer to the star than the habitable zone of the Sun
C) narrower and farther from the star than the habitable zone of the Sun
D) wider and farther from the star than the habitable zone of the Sun

Question 24

Stars much more luminous than the Sun have

A) narrower habitable zones, decreasing the odds of finding habitable planets and lifetimes too short for life to appear
B) wider habitable zones, increasing the odds of finding habitable planets but lifetimes too short for life to appear
C) narrower habitable zones, decreasing the odds of finding habitable planets but much longer lifetimes allowing life to appear and evolve
D) wider habitable zones, increasing the odds of finding habitable planets and much longer lifetimes allowing life to appear and evolve

Question 25

Which of the following factors influence the surface habitability of a planet?

A) planetary size
B) distance from parent star
C) presence of an atmopshere
D) all of these

Question 26

Overall, the likelihood of finding planets in a star's habitable zone depends on the

A) distance from the star to the outer edge of the zone
B) distance from the outer edge of the zone to the nearest other star
C) distance from the star to the inner edge of the zone
D) width of the zone

Question 27

Compared to today, in the future, the Sun's habitable zone will be

A) wider and closer to the Sun
B) narrower and closer to the Sun
C) narrower and farther from the Sun
D) wider and farther from the Sun

Question 28

A star more luminous than our Sun will have a habitable zone that is

A) narrower and farther from the star than the habitable zone of the Sun
B) narrower and closer to the star than the habitable zone of the Sun
C) wider and farther from the star than the habitable zone of the Sun
D) wider and closer to the star than the habitable zone of the Sun

Question 29

If we allow for a simple runaway greenhouse effect, the inner boundary of the Sun's habitable zone would be

A) roughly halfway between the orbits of Venus and Mercury
B) just outside the orbit of the planet Mercury
C) roughly half way between the orbits of the Earth and Venus
D) just inside the orbit of the Earth

Question 30

If we allow for moisture loss due to a moist greenhouse effect, the inner boundary of the Sun's habitable zone would be

A) just inside the orbit of the Earth
B) roughly halfway between the orbits of Venus and Mercury
C) roughly halfway between the orbits of the Earth and Venus
D) just outside the orbit of the planet Mercury

Question 31

Mars currently lacks surface habitability mostly because of

A) the chemical composition of its atmosphere
B) its distance from the Sun
C) its small size
D) the chemical composition of its surface

Question 32

According to optimistic estimates, the end of habitability of Earth will come about

A) a few hundred thousand years from now
B) a billion years from now
C) 3 to 4 billion years from now
D) 100 million years from now

Question 33

When the Sun was younger, how did its habitable zone compare with its habitable zone today?

A) narrower and closer to the Sun
B) narrower and farther from the Sun
C) wider and closer to the Sun
D) wider and farther from the Sun

Question 34

If we allow for a planet with an atmosphere lacking greenhouse gases or dust, the outer boundary of the Sun's habitable zone would be

A) at exactly the current orbital distance of Mars
B) well beyond the orbital distance of Mars
C) roughly halfway between the orbits of the Earth and Mars
D) just inside the orbit of Mars

Question 35

Stars much less luminous than the Sun have

A) wider habitable zones, increasing the odds of finding habitable planets and much longer lifetimes allowing life to appear and evolve
B) wider habitable zones, increasing the odds of finding habitable planets but lifetimes too short for life to appear
C) narrower habitable zones, decreasing the odds of finding habitable planets and lifetimes too short for life to appear
D) narrower habitable zones, decreasing the odds of finding habitable planets but much longer lifetimes allowing life to appear and evolve

Question 36

If we allow for a planet with a thick atmosphere and a strong greenhouse effect, the outer boundary of the Sun's habitable zone would be

A) at exactly the current orbital distance of Mars
B) well beyond the orbital distance of Mars
C) roughly halfway between the orbits of the Earth and Mars
D) just inside the orbit of Mars

Question 37

Optimistically, the habitable zone of the Sun (a G-star) is calculated to extend from about 0.84 to 1.7 AU, while the habitable zones of more massive and luminous A-stars are calculated to extend from about 3.8 to 7.6 AU. Given that G-stars are 7 times more numerous than A-stars, what is the percentage of planets expected in habitable zones around A-stars compared to G-stars like our Sun?

A) 63 %
B) 440 %
C) 31 %
D) 4.4 %

Question 38

The moist greenhouse effect refers to

A) the warming process by which water vapor rises into the upper atmosphere above the ozone layer where it is then broken apart by ultraviolet radiation
B) the point at which water is evaporating from the surface at a faster rate than it is condensing
C) the natural greenhouse effect due to clouds of water vapor in the lower atmosphere
D) an enhanced greenhouse effect above tropical regions of the Earth's surface

Question 39

The range of distances that has remained habitable for the entire duration of the Sun's lifetime is referred to as the

A) continuously habitable zone
B) habitable zone of consistency
C) zone of water stability
D) permanently habitable zone

Question 40

According to conservative estimates, the end of habitability of Earth will come about

A) 3 to 4 billion years from now
B) a few hundred thousand years from now
C) 100 million years from now
D) a billion years from now

Question 41

If global warming causes the frozen Arctic ocean to melt, global ocean levels will not rise since

A) the ice will reform in the Antarctic ocean
B) the melting of floating ice does not affect sea levels
C) the Greenland ice cap will thicken by a corresponding amount
D) more water will evaporate into the atmosphere

Question 42

Measurements of carbon dioxide concentrations in our atmosphere over the past 400,000 years show

A) an indirect correlation with global surface temperatures
B) a direct correlation with global surface temperatures, only over the past century
C) no correlation with global surface temperatures
D) a direct correlation with global surface temperatures

Question 43

When the Sun runs out of nuclear fuel and expands to become a red giant,

A) the Earth's oceans will freeze solid
B) the Earth will be ejected from the solar system
C) the Earth will be destroyed
D) the Earth will experience a runaway greenhouse effect followed by the total loss of its atmosphere

Question 44

As global warming progresses, the

A) landmasses will warm the most
B) equatorial regions will warm the most
C) polar regions will warm the most
D) oceans will warm the most

Question 45

When the Sun ejects its outer layer into space to become a planetary nebula, most likely the

A) Earth will be ejected from the solar system
B) Earth will probably be destroyed
C) Earth's oceans will freeze solid
D) Earth will experience a runaway greenhouse effect followed by the total loss of its atmosphere

Question 46

If we do nothing to slow our emissions of carbon dioxide and other greenhouse gases, by the end of the century the global average temperatures are predicted to increase by

A) 5 to 10 ^oC (10 to 20 ^oF)
B) 1 to 2 ^oC (2 to 4 ^oF)
C) 3 to 5 ^oC (6 to 10 ^oF)
D) less than 1 ^oC (2 ^oF)

Question 47

The Sun will end its life by becoming

A) a black hole
B) a neutron star
C) a white dwarf
D) none of these

Question 48

As global warming raises the moisture content in our atmosphere, storms will

A) become less numerous and less severe
B) disappear all together
C) become less numerous but more severe
D) become more numerous and severe

Question 49

The atmospheric carbon dioxide concentration

A) is higher than it has been at any time during the last million years
B) is higher than it has been at any time during the Earth's history
C) has remained roughly constant during the last million years
D) is lower than it has been at any time during the last million years

Question 50

Rising sea levels in the future will be linked mostly to the melting of

A) the Greenland ice cap only
B) the Antarctic ice cap only
C) the north polar ice cap
D) both the Antarctic and Greenland ice caps

Question 51

As the average surface temperature of the Earth rises, the Northern hemisphere of the Earth is warming more rapidly than the Southern hemisphere because

A) the Northern hemisphere contains more landmass which more readily absorbs solar radiation
B) during summer in the Northern hemisphere, the Earth is closer to the Sun
C) there is less ice in Arctic regions compared to the Antarctic regions so less radiation is reflected out into space
D) there are more clouds in the Southern hemisphere to reflect solar radiation out into space

Question 52

Over the last century, global temperatures have risen by about

A) 0.1 ^oC (0.2 ^oF)
B) 0.8 ^oC (1.4 ^oF)
C) 2.0 ^oC (3.6 ^oF)
D) 3.2 ^oC (5.8 ^oF)

Question 53

When the Sun becomes a red giant

A) some life on Earth may still be able to survive on the surface
B) life will probably not be able to survive even beneath the surface
C) life may still be able to survive in the atmosphere
D) the Earth will be destroyed

Question 54

The recent gradual rise in the Earth's average surface temperature is commonly referred to as

A) global warming
B) the greenhouse effect
C) ozone depletion
D) global heating

Question 55

While there is no doubt that global temperatures are increasing, it is

A) now becoming clear that human activity is indeed causing global warming
B) now becoming clear that this effect is due to the slow brightening of the Sun
C) now certain that human activity has no effect on the Earth's climate
D) still not clear whether human activity is affecting the climate at all

Question 56

As global warming continues, weather patterns will change causing

A) some parts of the Earth's landmass to become warmer while other parts will actually get colder. The ocean temperatures will continue to rise
B) only the oceans to become warmer while the landmasses will become colder
C) only the landmasses to become warmer while the oceans will become colder
D) all parts of the Earth's surface will become warmer

Question 57

Over the past decade, the north polar ice cap has shrunk by approximately

A) 50 %
B) 1 %
C) 20 %
D) 5 %

Question 58

During the last century, sea levels have risen by

A) about 1 meter
B) about 20 centimeters
C) about 2 millimeters
D) less than 1 millimeter

Question 59

The term "global warming" refers to an increase in the average temperature

A) at the poles
B) at the equator
C) of the ozone layer
D) of the planet as a whole

Question 60

Over the past century, the largest increase in global temperatures has occurred during the last

A) 30 years
B) 10 years
C) 50 years
D) 2 years