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NASA Science News for August 8, 2007
On Sept. 1st, a flurry of bright and oddly-colored meteors could spill across the skies of western North America–or not. Forecasters are divided about what will happen next month when Earth runs into an ancient stream of debris from mysterious Comet Kiess.
A spectacular meteor shower might be in the offing late next summer, SPACE.com has learned. It may not last very long, but could produce a bevy of bright, swift shooting stars for favorably positioned skywatchers. The prediction is found in a technical report, co-authored by two astronomers who are targeting Sept. 1, 2007 as the date for the potential display.The meteors are called “Aurigids” because they appear to fan-out from the constellation of Auriga, the Charioteer. At least a strong shower
Meteor showers occur whenever we ride into the dusty debris left behind in a comet’s orbit. The debris left behind by Kiess, a comet last seen in 1911, is what produces the Aurigids. The comet takes approximately 2,500 years to orbit the Sun, but there are also dense trails of dust traveling along its orbit. Earth has had glancing blows in the past with a few of these dust trails in 1935, 1986 and 1994.
In 2007, however, the Earth is expected to pass very close to the center of a dust trail, which astronomers Esko Lyytinen of Finland and Peter Jenniskens of the SETI Institute in California said, should result in “a spectacularly rich shower of bright meteors.”
The researchers in the past used computer models to predict outbursts of the Leonid meteor shower, which wowed skywatchers in 2001 and 2002.
Shooting stars, or meteors, are common any night of the year; five or six per hour are normal. During a respectable meteor shower, they can be seen streaking across the sky every few minutes. But occasionally the sky explodes in a shower of sparks, a rare meteor “storm” that is something to get excited about.
Meteor storm possible? No one is certain how strong next year’s Aurigids may be, but tomorrow, Jenniskens will make an announcement at the General Assembly of the International Astronomical Union in Prague concerning an “Aurigid Meteor Storm” of Sept. 1, 2007.
Meteor storms are typically said to involve at least 1,000 meteors per hour, a rate sometimes achieved only in 15-minute bursts. It is not clear what sort of hourly rate Jenniskens will announce as his prediction, however.
“I do not know why Peter Jenniskens will announce this as a storm,” Lyytinen told SPACE.com. “I have not especially tried to predict the strength but I would guess only a good or moderate shower, a storm not impossible.”
The peak of the shower is predicted to occur at 11:37 GMT. Unfortunately this comes during daylight for Europe and much of North America. But the western United States and Canada, as well as much of Alaska and Hawaii will still be in pre-dawn darkness and would be in an excellent position to view it.
Another drawback will be a gibbous Moon, four days past full, whose light could interfere with observing. But, Lytinnen said, many of the meteors are expected to be very bright. “So, maybe the moon does not make very much harm in the observations … I hope.”
At the International Astronomical Union General Assembly in Prague today, Peter Jenniskens revealed his outlook for the 2007 Aurigid Meteor Shower. He forecast rates of at least 400, possibly even exceeding 1,000 meteors per hour.
This prediction is based on the modeling of the trajectories of dust particles ejected from comet Kiess, which in turn fits the three past outbursts of the Aurigids. But this time we will hit-according to the model-very close to the center of the dust cloud, within 39,000 miles (63,000 km.). Since this has never been the case with this shower before, there’s no way to know how strong the shower might be.
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