Green beam

On a clear evening, when the Sun descends beyond the horizon, one can observe one of the most beautiful and unusual phenomena of nature - the green beam. At the moment when the disk of the Sun is hiding, the last sunbeam for a moment becomes bright green.

On a clear evening, when the Sun descends beyond the horizon, one can observe one of the most beautiful and unusual phenomena of nature - the green beam

The green beam - the so-called flash on the Sun - sometimes happens in blue or goes from green to blue; they even saw a purple ray. Occasionally it appears when the entire disk of the Sun is still above the horizon; at that moment the beam may be red at the bottom of the disc and green or blue at the top.

Green beam is not easy to see. However, even the ancient Egyptians were familiar with this phenomenon. On a stone column dating back to about 2500 BC, painted the setting (or ascending?) Sun in the form of a semicircle, painted in purple at the top and green below.

Green beam is not easy to see. However, even the ancient Egyptians were familiar with this phenomenon

Some who have heard of the green beam, but who have vainly tried to see it, consider this phenomenon the fruit of somebody's imagination or an optical illusion. "It's the fatigue of the reticular shell of the eye", others say. "Look at the bright light for a long time, and then look away, you'll see additional colors".

The achievements of color photography gave irrefutable proof of the reality of the green beam. These pictures were received in 1954 after a long series of experiments by S. Troisch, instrumentalist and photographer of the Vatican Observatory. It was difficult to work out the appropriate technique. It seemed impossible to find an exposure that would give the exact reproduction of an instantly disappearing phenomenon on the film. Another difficulty was that while the Sun was above the horizon, the light from the disk was brighter than the light from the green beam.

Most of the photos were taken with a telescope. Further study of the green beam and related phenomena will increase our knowledge of the upper atmosphere.

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