De hemel kleurt groen, maar het is geen aurora borealis
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De hemel kleurt groen, maar het is geen aurora borealis
NORTHERN SKY TURNS GREEN, NO AURORAS REQUIRED:
There was no geomagnetic storm on July 18th, but northern skies turned green anyway. Photographer Bryan Hansel recorded the phenomenon over rural Hovland, Minnesota:
Bryan Hansel
The green glow was barely visible to the naked eye, but a deep-sky exposure with Hansel's Nikon D800 digital camera captured it easily.
This is called "airglow." Although it resembles the aurora borealis, the underlying physics is different. Airglow is caused by an assortment of chemical reactions in the upper atmosphere driven mainly by solar ultraviolet radiation; auroras, on the other hand, are ignited by gusts of solar wind. Green airglow is best photographed from extremely dark sites on nights when the Moon is new or below the horizon. It often shows up in long exposures of the Milky Way.
Indeed, the Milky Way was Hansel's actual target. "I run a Milky Way Photography Workshop," he explains."The figures on the dock are three of the photographers in my group and the light is from a camera's LCD screen."
Bron:http://www.spaceweather.com/ | Gewijzigd: 30 januari 2017, 14:11 uur, door Joyce.s
There was no geomagnetic storm on July 18th, but northern skies turned green anyway. Photographer Bryan Hansel recorded the phenomenon over rural Hovland, Minnesota:
Bryan Hansel
The green glow was barely visible to the naked eye, but a deep-sky exposure with Hansel's Nikon D800 digital camera captured it easily.
This is called "airglow." Although it resembles the aurora borealis, the underlying physics is different. Airglow is caused by an assortment of chemical reactions in the upper atmosphere driven mainly by solar ultraviolet radiation; auroras, on the other hand, are ignited by gusts of solar wind. Green airglow is best photographed from extremely dark sites on nights when the Moon is new or below the horizon. It often shows up in long exposures of the Milky Way.
Indeed, the Milky Way was Hansel's actual target. "I run a Milky Way Photography Workshop," he explains."The figures on the dock are three of the photographers in my group and the light is from a camera's LCD screen."
Bron:http://www.spaceweather.com/ | Gewijzigd: 30 januari 2017, 14:11 uur, door Joyce.s
