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Ch. 10 AST 105

Terms in this set (30)

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
just inside the orbit of Mars
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
3 to 5 deg C (6 to 10 deg F)
As global warming raises the moisture content in our atmosphere, storms will
become more numerous and severe
Over the past decade, the north polar ice cap has shrunk by approximately
20%
Over the past century, the largest increase in global temperatures has occurred during the last
30 years
If global warming causes the frozen Arctic ocean to melt, global ocean levels will not rise since
the melting of floating ice does not affect sea levels
Overall, the likelihood of finding planets in a star's habitable zone depends on the
width of the zone
The possible habitability of Mars today is mostly determined by
geological conditions existing beneath its surface
As global warming continues, weather patterns will change causing
some parts of the Earth's landmass to become warmer while other parts will actually get colder. The ocean temperatures will continue to rise
Europa is located outside the Sun's habitable zone and yet may be habitable. How can this be?
Europa is tidally heated, allowing liquid water to exist beneath its icy surface
What is the definition of a star's habitable zone?
the range of distances from the star where liquid water can be stable on the surface of a suitable planet
Most of the carbon dioxide on Venus
is present in its atmosphere
Why does the Sun brighten with time?
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
When the Sun ejects its outer layer into space to become a planetary nebula, most likely the
Earth will probably be destroyed
Based solely on its distance from the Sun, we would expect the surface of Venus to be
hotter than the Earth but not so hot that liquid water could not exist
Observations by the Venus Express orbiter have shown
evidence for recent volcanic lava flows occurring within the last 250,000 years
Unlike the Earth, Venus does not have a protective magnetic field because
of its slow rotation
Which of the following factors influence the surface habitability of a planet?
presence of an atmosphere, distance from parent star, planetary size
When the Sun was younger, how did its habitable zone compare with its habitable zone today?
narrower and closer to the Sun
The atmospheric carbon dioxide concentration
is higher than it has been at any time during the last million years
Which of the following statements regarding the determination of surface habitability and subsurface habitability of a planet is correct?
surface habitability can be determined remotely by studying reflected starlight from a planet, while determining subsurface habitability would require a robotic space probe
Over the last century, global temperatures have risen by about
0.8 deg C (1.4 deg F)
If life is present on Venus today, it will most likely be
found in the atmosphere where droplets of water can be found
A star less luminous than our Sun will have a habitable zone that is
narrower and closer to the star than the habitable zone of the Sun
The clouds of sulfuric acid present in the venusian atmosphere probably result from
the chemical reaction of sulfur dioxide produced by outgassing volcanoes and water
When the Sun becomes a red giant
life will probably not be able to survive even beneath the surface
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?
63 %
Venus is located
outside the Sun's habitable zone
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
they are very common
The range of distances that has remained habitable for the entire duration of the Sun's lifetime is referred to as the
continuously habitable zone
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