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Astro2021 cpt 10

Terms in this set (65)

the range of distances from the star where liquid water can be stable on the surface of a suitable planet
What is the definition of a star's habitable zone?
exists around all stars
A habitable zone
move outward
Over time, as they age, the habitable zone of stars like our Sun
Europa is tidally heated, allowing liquid water to exist beneath its icy surface
Europa is located outside the Sun's habitable zone and yet may be habitable. How can this be?
the Moon is too small to retain an atmosphere necessary for liquid water to be stable
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?
surface habitability can be determined remotely by studying reflected starlight from a planet, while determining subsurface habitability would require a robotic space probe
Which of the following statements regarding the determination of surface habitability and subsurface habitability of a planet is correct?
the size of the planet
Apart from its distance from its parent star, what is the next most important factor that determines a planet's habitability?
have thick, hydrogen atmospheres
Theoretical calculations suggest that Earth-sized planets could be habitable on their surfaces outside of habitable zones if they
warmer than the Earth, but not so warm that liquid water could not exist
Based solely on its distance from the Sun, we would expect the surface of Venus to be
only be slightly warmer
If Venus had the same atmosphere as the Earth, it would
is present in its atmosphere
Most of the carbon dioxide on Venus
is locked up in carbonate rocks in its crust or is dissolved in the oceans
Most of the carbon dioxide on the Earth
it condensed into the oceans
When the Earth first formed it had large quantities of water vapor in its atmosphere while today the levels of water vapor are much lower. Where did most of the water vapor go?
it was destroyed in the atmosphere by ultraviolet light from the Sun
When Venus first formed it had large quantities of water vapor in its atmosphere while today only very low levels of water are present. Where did most of the water vapor go?
the presence of sulfuric acid clouds in the atmosphere
, and the detection from orbit of elevated levels of infrared radiation from volcanic features on the surface
Which of the following provides evidence for active volcanism on Venus today and in the past?
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
Evidence for the loss of water from the atmosphere of Venus via the action of ultraviolet light comes from the
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
If the Earth were to be moved to where Venus is today,
outside the Sun's habitable zone
Venus is located
between the orbits of the Earth and Venus
The inner boundary of the Sun's habitable zone currently lies
the Sun was dimmer so Venus would have received less radiation
Around 4 billion years ago Venus could have been more Earth-like with liquid water on its surface because
found in the atmosphere where highly acidic droplets of water can be found
If life is present on Venus today, it will most likely be
distance from the Sun
The case of Venus tells us that which of the following is a critical factor in determining surface habitability?
planetary size
The case of Mars tells us that which of the following is a critical factor in determining surface habitability?
wider and farther from the star than the habitable zone of the Sun
A star more luminous than our Sun will have a habitable zone that is
narrower and closer to the star than the habitable zone of the Sun
A star less luminous than our Sun will have a habitable zone that is
wider habitable zones, increasing the odds of finding habitable planets but lifetimes too short for life to appear
Stars much more luminous than the Sun have
narrower habitable zones, decreasing the odds of finding habitable planets but much longer lifetimes allowing life to appear and evolve
Stars much less luminous than the Sun have
have extremely short lifetimes of the order of millions of years
Although stars much more luminous than our Sun have wider habitable zones, planets around them are unlikely to have developed life because high luminosity stars
have very narrow habitable zones
Although low luminosity stars are very common, the probability of individual stars having planets within their habitable zones is low because low luminosity stars
the Moon
If distance from the Sun were the only factor affecting surface habitability, which of the following would be habitable?
plate tectonics to be present
The minimum size that makes it possible for a planetary surface to remain habitable over long time periods is a size that allows
its small size
Mars currently lacks surface habitability mostly because of
it is too small
, and its crust is too dry and stiff to break into plates
What is a possible reason why Venus does not have plate tectonics?
presence of a magnetic field
Which is NOT a critical factor that determines the habitability of a rocky planet?
size
， distance from parent star
， and presence of an atmosphere
Which of the following is a crucial factor in enabling habitability on the surface of a rocky planet?
it exerts a pressure which allows liquid water to be stable
, and it protects the surface against harmful solar radiation
What role does an atmosphere play in surface habitability?
thermal escape
, large impacts
, and solar wind stripping
What can contribute to a planet losing its atmosphere?
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
The moist greenhouse effect refers to
just inside the orbit of the Earth
If we allow for moisture loss due to a moist greenhouse effect, the inner boundary of the Sun's habitable zone would be
roughly half way between the orbits of the Earth and Venus
If we allow for a simple runaway greenhouse effect, the inner boundary of the Sun's habitable zone would be
just beyond the orbit of Mars
If Mars had a thicker atmosphere with a strong greenhouse effect, the outer boundary of the Sun's habitable zone would lie
narrower and closer to the Sun
When the Sun was younger, how did its habitable zone compare with its habitable zone today?
wider and farther from the Sun
Compared to today, in the future, the Sun's habitable zone will be
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
Why does the Sun brighten with time?
continuously habitable zone
The range of distances that has remained habitable for the entire duration of the Sun's lifetime is referred to as the
a billion years from now
According to conservative estimates, the end of habitability of Earth will come about
3 to 4 billion years from now
According to optimistic estimates, the end of habitability of Earth will come about
the Earth will experience a runaway greenhouse effect followed by the total loss of its atmosphere
When the Sun runs out of nuclear fuel and expands to become a red giant,
life will probably not be able to survive even beneath the surface
When the Sun becomes a red giant
Earth will be destroyed
When the Sun ejects its outer layer into space to become a planetary nebula, most likely the
global warming
The recent gradual rise in the Earth's average surface temperature is commonly referred to as
orbiting satellites
, weather stations
, and water temperature measurements by ships
Today, global average temperatures are estimated using
risen by about 0.85°C (1.5°F)
Over the last century, global average temperatures have
the amount of the rise in the atmospheric concentration tracks almost perfectly with the amount of carbon dioxide being released by industry
, estimates of changes in the amount of carbon dioxide from natural sources such as volcanoes and the oceans can account for no more than about 1% of the rise in the atmospheric concentration
, and the ratio of carbon isotopes is consistent with the increase in carbon dioxide levels coming primarily from the burning of fossil fuels
Evidence that the recent rise in carbon dioxide concentration is due to human activity and not natural factors comes from
the Northern hemisphere contains more landmass which more readily absorbs solar radiation
As the average surface temperature of the Earth rises, the Northern hemisphere of the Earth is warming more rapidly than the Southern hemisphere because
ice cores drilled out of the Antarctic ice sheet
Long-term data on global carbon dioxide levels can be obtained from analyzing air trapped in
a direct correlation with global surface temperatures
Measurements of carbon dioxide concentrations in our atmosphere over the past 800,000 years show
is higher than it has been at any time during the last 800,000 years
The atmospheric carbon dioxide concentration
now becoming clear that human activity is indeed a major contributor to global warming
While there is no doubt that global temperatures are increasing, it is
match real climate data quite well
Climate models which have been developed over many decades
completely fail to match real climate data
Climate models which ignore human activity
some parts of the Earth's landmass to become warmer while other parts will experience more extreme winters. The ocean temperatures will continue to rise
As global warming continues, weather patterns will change causing
polar regions will warm the most
As global warming progresses, the
become more numerous and severe
As global warming raises the moisture content in our atmosphere, storms will
may rise by several meters
Climate models predict that due to the melting of the polar ice caps, sea levels by the end of this century
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