The faint young Sun paradox or problem describes the apparent contradiction between observations of liquid water early in the Earth's history and the astrophysical expectation that the Sun's output would be only 70% as intense during that epoch as it is during the modern epoch. The issue was raised by astronomers Carl Sagan and George Mullen in 1972. Explanations of this paradox have taken into account greenhouse effects, astrophysical influences, or a combination of the two.
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Famous quotes containing the words faint, young, sun and/or paradox:
“The waves have now a redder glow—
The hours are breathing faint and low—
And when, amid no earthly moans,
Down, down that town shall settle hence,
Hell, rising from a thousand thrones,
Shall do it reverence.”
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—Henry David Thoreau (1817–1862)
“...This
is the paradox of vision:
Sharp perception softens
our existence in the world.”
—Susan Griffin (b. 1943)