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METEORS FROM HALLEY'S COMET: Earth is entering a stream of debris from Halley's Comet, source of the annual eta Aquarid meteor shower. Because the shower's radiant is located below the celestial equator, southern hemisphere observers are favored, but even northerners will be able to see at least a few flecks of Halley-dust disintegrating in the atmosphere when the shower peaks this weekend. The best time to look is during the hours before sunrise on Sunday, May 6th. Bright moonlight will cap the meteor rate at about 30 per hour.
In recent nights, NASA's all-sky meteor network has picked up a number of early eta Aquarid fireballs. This one was bright enough to shine through the glow of sunrise and clouds over Tullahoma, Tennessee, on April 29th:
According to analysts at NASA's Meteoroid Environment Office, this particular speck of comet dust hit the atmosphere traveling 62 km/s (139,000 mph) and disintegrated about 84 km (52 mi) above Earth's surface.
The full Moon of May 5-6, 2012, with interfere with the visibility of the eta Aquarid peak. Radar signals, however, penetrate moonlight with ease. Tune into Space Weather Radio for live echoes from eta Aquarids passing over the US Air Force Space Surveillance Radar in Texas.
THWARTED ESCAPE: Solar activity is low, with only a smattering of minor C-class flares coming from a few 'active regions' scattered across the solar disk. An eruption from sunspot AR1465 on April 29th didn't even get off the ground. NASA's Solar Dynamics Observatory recorded the thwarted escape:
It was AR1465 vs. gravity, and gravity won.
Solar activity should remain low for the next 24 to 48 hours, with no more than a 1% chance of X-class solar flares. As the movie above shows, however, even a weak eruption on the sun is worth watching. Stay tuned for more. Solar flare alerts: text, voice.
more images: from Alan Friedman of Buffalo, NY; from John Stetson of Falmouth, Maine
FIREBALL PHOTOS WANTED: Meteor expert Peter Jenniskens of NASA's Ames Research Center could use some help from the general public--in particular, photographers and business owners with security cameras in central California. He needs photos of the mini-van sized asteroid that exploded over the region on Sunday morning, April 22nd, at 7:51 am PDT. "Our goal is to determine the orbit of the object and to understand how this small asteroid fell apart when it entered the earth's atmosphere," he explains. [Got photos? Submit them here.]
Meteorite hunters, Jenniskens included, are starting to find pieces of the asteroid on the the ground. These samples were lying in the parking lot of Henningsen-Lotus Park, apparently crushed by a passing car:
The meteorites landed not far from Sutter's Mill in El Dorado County, CA, the same place gold was discovered in the 19th century, triggering the California Gold Rush. Jenniskens likens the thrill of finding these space rocks to finding gold: " I think John A. Sutter must have felt the same way when he found the first gold nugget back in January of 1848."
"The meteorites appear to be CM chondrites," he continues. This would make the sample very primitive, possibly contiaining minerals and compounds preserved from a time when the solar system was very young. "I can not say more as the samples have not yet been analyzed. My main concern now is to recover perishable data of the fireball, such as video security camera footage."
More footage will help researchers answer questions like these: "Was this a rubble pile or a monolitihic block? Was the orbit very evolved, or could its semi-major axis perhaps still point us to the source region of CM chondrites in the asteroid belt?" Jeniskens wonders. "This is a rare opportunity to learn about the properties of a particular class of near-Earth objects."
News reports: #1, #2, #3.