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OCA Chapter 10

Terms in this set (30)

The recent gradual rise in the Earth's average surface temperature is common referred to as?
Global warming
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
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
The moon is the habitable zone of the sun at the same distance but it is not habitable. How can this be?
the moon is too small to retain an atmosphere necessary for liquid water to be stable
The atmospheric carbon dioxide concentration is higher or lower?
Is higher than it has been at any time during the last million years
Why does the Sun brighten with time?
as hydrogen is converted into helium at its core, the number of hydrogen nuclei decreases, decreasing the fusion rate. To maintain the balance with gravity pressing inward, the core compensates by shrinking up and heating up
When the sun runs out of nuclear fuel and expands to become a red giant
the Earth will experience a runaway greenhouse effect (like Venus) followed by the total loss of its atmosphere
The moist greenhouse effect refers to what?
The warming process by which water vapor rises into the upper atmosphere above the ozone layer where it is then broken apart by UV radiation
According to conservative estimates, the end of habitability of Earth will come about when?
a billion years from now
When the sun was younger, how did its habitable zone compare with its habitable zone today?
narrower and closer to the sun
Over time, the Sun's habitable zone has?
widened and moved away from the sun
Around 4 billion years ago, Venus could have been more Earth like with liquid water on its surface because?
the Sun was dimmer so Venus would have received less radiation
Over the past century the largest increase in global temperatures has occurred during the last how many years?
50 years
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 what?
just inside the orbit of Mars
Rising sea levels in the future will be linked mostly to the melting of what?
both the Antarctic and Greenland ice caps
The range of distances that has remained habitable for the entire duration of the Sun's lifetime is referred to as what?
continuously habitable zone
If the Earth were to be moved to where Venus is today, what would happen?
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
A star more luminous than our Sun will have a habitable zone that is what?
wider and farther from the star than the habitable zone of the Sun
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 what?
they are very common
If life is present on Venus today, it will most likely be?
found in the atmosphere where droplets of water can be found
As global warming progresses, the?
polar regions will warm the most
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
Overall, the likelihood of finding planets in a star's habitable zone depends on the?
width of the zone
Most of the carbon dioxide on Venus is?
is present in its atmosphere
Most of the water that used to be present in the Venusian atmosphere is?
was destroyed in the atmosphere by ultraviolet light from the Sun
Which of the following factors influence the surface habitability of a planet?
all of these i.e.

1. distance from the parent stars
2. planetary size
3. presence of an atmosphere
Over the last century, global temperatures have risen by about how many degrees?
0.8 oC
Apart from its distance from its parent star, what is the next most important factor that determines a planet's habitability?
the size of the planet
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?
well beyond the orbital distance of Mars
Evidence for the loss of water from the atmosphere of Venus via the action of ultraviolet light comes from the?
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
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