Mon, 20 Aug 2012 11:59 CDT
High above Earth in the realm of meteors and noctilucent clouds, a strange and beautiful form of lightning dances at the edge of space. Researchers call the bolts "sprites"; they are red
, and tend to come in bunches
. Jesper Grønne of Silkeborg, Denmark, photographed these specimens on August 15th:
© Jesper Grønne
After several years of hunting sprites from my location in Denmark, I finally caught some last week--the first danish Red Sprites ever photographed," says Grønne. "They were located 50 km to 90 km above a thunderstorm some 350 km away over the North Sea. There were 2 flashes, each producing 5-6 individual Red Sprites."
"Sprites are a true space weather phenomenon," explains lightning scientist Oscar van der Velde of Sant Vicenç de Castellet, Spain. "They develop in mid-air around 80 km altitude
, growing in both directions, first down, then up. This happens when a fierce lightning bolt draws lots of charge from a cloud near Earth's surface. Electric fields [shoot] to the top of Earth's atmosphere--and the result is a sprite. The entire process takes about 20 milliseconds."
Although sprites have been seen for at least a century, most scientists did not believe they existed until after 1989 when sprites were photographed by cameras onboard the space shuttle. Now "sprite chasers
" routinely photograph sprites from their own homes. "I used an astro-modified Canon 5D II in video-mode to catch my sprites," says Grønne. Give it a try!
Diagram: How to Look for Sprites
(used with permission of sky-fire.tv