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MISSING GAMMA-RAY
BURSTS: A group of gamma-ray bursts at the
edge of the Universe has gone missing. This week, researchers have
gathered to discuss their whereabouts at a special meeting on gamma-ray
mysteries: full
story.
ORIONID OUTBURST:
The 2008 Orionid meteor shower put on a surprisingly
good show. At maximum on Oct. 21st, observers around the world counted
40+ meteors per hour, about twice the usual rate. A fireball monitoring
station at the Marshall Space Flight Center in Huntsville, Alabama,
recorded this flurry:
Click
to view a larger movie (2 MB gif)
In the movie, the "floodlight" arcing slowly across the
sky is the Moon. "Lunar glare should have spoiled the show,
but the shower was so bright, we saw it despite the Moon's interference,"
says Bill Cooke of NASA's Meteoroid Environment Office.
The source of the Orionid meteor shower is Halley's Comet. Every
year in October, Earth's crosses a stream of Halley-dust, and meteors
fly out of the constellation Orion. The extra Orionids of 2008 probably
came from a denser-than-usual filament of dust. This is the third
October in a row Orionids have surged, suggesting a trend. Maybe
next year's outburst won't be such a surprise!
UPDATED: 2008
Orionid Meteor Gallery
[IMO meteor counts]
[2006 Orionids]
SUNSET MIRAGE:
According to the California almanac, on Oct. 16th the San Francisco
sun should have set at 6:30 pm sharp, yet when photographer Mila
Zinkova looked at 6:36 pm the sun was still "up"--in
strangely distorted form:
"The explanation is simple," says Zinkova. "The
picture I took was not a picture of the sun itself, but a mirage
of the sun." Furthermore, she points out, there is a boat in
the scene--it is the towering brown blob in the foreground! "The
view was just incredible."
Atmospheric optics expert Les Cowley explains what happened: "To
make this sun mirage, light from the already set sun was channelled
around the curvature of the earth inside an immense atmospheric
waveguide. Very strong multiple temperature
inversions refracted the sun's rays to make a ducted
mock-mirage
sunset. The nearby boat was also miraged. The California Coast with
its cold ocean currents overlaid by warm winds from the land is
ideal for seeing sights like these."
more images: from
Aymen Ibrahem of Alexandria, Egypt; from
Tamas Ladanyi of Balatonvilagos, Hungary; from
Simon Thomas of Porec, Croatia; from
Peter Pammer of Jauerling, Austria
Oct.
2008 Aurora Gallery
[Previous Octobers: 2007,
2006, 2004,
2003, 2002,
2001,
2000]
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