QUIET, WITH A SLIGHT CHANCE OF FLARES: Solar activity is low, and it is likely to stay that way through the weekend. NOAA forecasters say there is only a slight 15% chance of M-class solar flares for the next 48 hours. Free: Solar Flare Alerts
SPRITE-Y NIGHT IN SLOVAKIA: It was a dark and stormy night. After sunset on Friday, Aug. 18th, photographer Ondrej Kralik was hiking through the Low Tatras, a mountain range in central Slovakia. He could see stars overhead, but the horizon was flashing with the impulsive glow of lightning. "I thought a storm was coming," says Kralik, who trained his camera in the direction of the flashes. Instead of capturing the downward strike of lightning, however, he saw sprites:
"I quickly realized that the storm was far away, and I could see over the top of the thunderheads. Sprites were dancing along the cloudtops," says Kralik. "I saw this bright cluster of sprites with the naked eye and my camera captured it as well. Its brightness is approximately -6.7 mag, and it was located about 510 km far above southeast Germany."
"In the foreground under the sprites you can see the main ridge of Low Tatras, (Chabenec 1995 m) and Kotliska (1937 m) on the left," he says. "I was lucky to witness one of the brightest sprites, but as they say, fortune favors the prepared."
Sometimes called "space lightning," sprites are a true space weather phenomenon. They inhabit the upper atmosphere alongside auroras, meteors and noctilucent clouds. Some researchers believe they are linked to cosmic rays: subatomic particles from deep space striking the top of Earth's atmosphere produce secondary electrons that, in turn, kickstart sprites in the highly-charged environment above thunderstorms.
The link to cosmic rays is particularly interesting at this time. For the past two years, space weather balloons have observed a steady increase in cosmic rays penetrating our atmosphere. This increase is largely due to the decline of the solar cycle. Flagging solar wind pressure and weakening sunspot magnetic fields allow more cosmic rays into the inner solar system--a trend which is expected to continue for years to come. So stay tuned for more sprites.
SOLAR ECLIPSE IN THE STRATOSPHERE: During the Great American Solar Eclipse on August 21st, the students of Earth to Sky Calculus and Spaceweather.com launched 11 high-altitude balloons from 5 states in the path of totality. We hoped to catch the Moon's shadow sweeping across the landscape from a vantage point in the stratosphere--and we succeeded. These pictures show the inky-black shadow of the Moon darkening a 70 mile-wide patch of Wyoming/Nebraska:
The camera, a Panasonic GH4, belonged to professional photographer Josh Stansfield. He helped students launch the balloon from Ft. Laramie, Wyoming, and later processed these unique images after the payload was recovered from its landing site in Nebraska.
Another Earth to Sky balloon launched from Wyoming captured a complete HD video of the Moon's shadow racing across the landscape. The launch team is processing it now, and it will be posted soon.
Photography was just one reason for launching so many balloons. We also flew cosmic ray sensors that sampled atmospheric radiation over 7 states (Oregon, Idaho, Wyoming, Kansas, Nebraska, Missouri and Illinois) while temperature and pressure sensors measured the effect of the Moon's shadow on the thermal structure of the atmosphere. A first look at the data suggests that the Moon's space-cold shadow might have the power to make helium balloons explode! Processing all of the data may take days or weeks; right now we're just scratching the surface. Stay tuned for more results.
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