Explanation:
What's happening over the horizon?
Although the scene may appear somehow
supernatural,
nothing more unusual is occurring than a
setting Sun and some well placed clouds.
Pictured above are
anticrepuscular rays.
To understand them, start by picturing common
crepuscular rays that are seen any time that sunlight pours though scattered clouds.
Now although sunlight indeed travels along
straight lines, the projections of these lines onto the
spherical sky are
great circles.
Therefore, the
crepuscular rays from a
setting (or rising) sun
will appear to re-converge on the other side of the sky.
At the anti-solar point 180 degrees around from the
Sun, they are referred to as
anticrepuscular rays.
Pictured above is a particularly striking set of
anticrepuscular rays photographed in 2001
from a moving car just outside of Boulder,
Colorado,
USA.
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