|
Credit & Copyright: Mario Cogo
Explanation:
Difficult to observe, the momentary
green flash above
the rising or setting sun
has been documented as
a phenomenon caused by the atmospheric
bending or refraction of sunlight.
Like a weak prism, the Earth's atmosphere breaks
white sunlight into
colors, bending red colors slightly and green and blue colors
through increasingly larger angles.
When the sky is clear, a
green flash just above the sun's edge
can sometimes be seen for a second or so, when the sun is
close to a distant horizon.
A blue flash is even harder to see though, because the atmosphere
must be extraordinarily clear to avoid scattering
and diminishing the refracted blue sunlight.
Still, from a site near
Roques de los Muchachos (altitude 2,400 meters) on La Palma
in the Canary Islands,
astrophotographer Mario Cogo captured this dramatic telescopic image of
a blue flash on color film in October of 2001.
The image of the setting Sun with large sunspot groups
on its surface is heavily distorted by atmospheric layers.
A lingering green rim is just visible under the tantalizing
blue flash.
|
January February March April May June July August September October November December |
| ||||||||||||||||||||||||||||||||||||||||||||||||
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: green flash - blue flash - refraction
Publications with words: green flash - blue flash - refraction
See also: