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CHANCE OF STORMS: NOAA forecastesrs estimate a 65% chance of polar geomagnetic storms on August 10th when one and perhaps two CMEs are expected to hit Earth's magnetic field. The incoming clouds were propelled from the sun by a flurry of erupting magnetic filaments on Aug. 6-7. High-latitude sky watchers should be alert for auroras.
Aurora alerts: text,
voice.
SPACE CHASE: On August 3rd, Japan launched a robotic spacecraft, the HTV-4, to re-supply the International Space Station (ISS). Last night, Larry Sloss saw the HTV-4 in hot pursuit of the ISS in the twilight skies over Priest Lake, Idaho:
"The HTV-4 was trailing the ISS by just 3 seconds," says Sloss.
Many observers noted "HTV-4 flares" this week. Apparently sunlight is glinting off a flat surface of the spacecraft, briefly raising its luminosity to match that of the much larger ISS. Sloss saw one too: "In the image, a brief, bright flare from the HTV-4 is slightly offset from the ISS trail."
HTV-4 has an interesting payload. Among the 5.4 tons of food, spare parts, and other supplies are
Kirobo, a talking robot to join the crew of the ISS, and
Firestation, an experiment to study mysterious Terrestrial Gamma-ray Flashes. Docking is scheduled at approximately 4:30 AM EDT on Friday August 9th.
SPRITES AND JETS OVER OKLAHOMA CITY: High above Earth in the realm of meteors and noctilucent clouds, a strange form of lightning dances at the edge of space. Researchers call the bolts "
sprites," and they are as beautiful as they are mysterious. Jason Ahrns, a graduate student from the University of Alaska Fairbanks, photographed a cluster of
bright red sprites over Oklahoma City on August 6th. Click on the arrow to view a rare high-speed movie of the phenomenon:
"I normally study auroras," says Ahrns, "but I've become involved in sprites as a side interest." At the time of the photo, Ahrns was flying onboard a
Gulfstream V operated by the National Center for Atmospheric Research (NCAR). "We try to get off to the side of sprite-producing storms, ideally about 200 km away, and film them with a couple of Phantom cameras running at 10,000 frames per second. One of the Phantoms has a diffraction grating in front of it to capture high speed spectra, which I don't think has ever been done before."
"We've also managed to record a few sprites over a lightning mapping array so we can identify the exact lightning strike that caused the sprite," he continues. "This has also never done before, and should provide insight into what type of lightning causes sprites."
"Lately," says Ahrns, "I've begun slipping
my personal camera into a spare window of the airplane, and the results have been so impressive that we're planning to make a dSLR (digital camera) a regular part of future campaigns. On August 3rd I recorded
some blue jets over Oklahoma city; I believe these are the first blue jets recorded by an ordinary dSLR." More tales of sprite-chasing may be found on
Ahrns' personal blog.
METEOR RADAR: The Canadian Meteor Orbit Radar (CMOR) is scanning the skies over North America for signs of meteor activity. This all-sky map produced during the early hours of August 8th shows a clustering of echoes in the constellation Perseus:
The meteors CMOR is detecting come from Comet 109P/Swift-Tuttle, source of the annual Perseid meteor shower. Earth is entering Swift-Tuttle's debris stream and Perseid activity is picking up. Forecasters expect the shower to peak on August 12-13 with as many as 100 meteors per hour.
Be alert for fireballs!
Potentially Hazardous Asteroids (
PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding
new ones all the time.
On August 9, 2013 there were 1397 potentially hazardous asteroids.
Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.
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| | 3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| | Realtime and archival images of the Sun from SOHO. |
| | from the NOAA Space Environment Center |
| | the underlying science of space weather |
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