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Meteor showers still surprise astronomers

Kappa Cygnid meteor, shown here, popped up unexpectedly during the Perseids meteor shower. An astronomer wonders if these light shows will ever be as predictable as lunar eclipses.
Kappa Cygnid meteor, shown here, popped up unexpectedly during the Perseids meteor shower. An astronomer wonders if these light shows will ever be as predictable as lunar eclipses. Jan Eric Krikke
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An unexpected meteor shower popped up during the annual Perseids shower Aug. 11-13, 2007. Among the fast-moving Perseids were several slow-moving meteors from a shower called the "Kappa Cygnids," radiating from a point between the bright stars of Vega and Deneb. Some meteors were as bright as the first quarter moon and flashed in multiple colors.

Koen Miskotte, a leading amateur astronomer of the Dutch Meteor Society, first alerted us to the shower. Many Kappa Cygnids exhibited irregular light curves and end flares. Spanish astronomers Josep M. Trigo-Rodríguez of the Institute of Space Sciences and José M. Madiedo of the University of Huelva reported that the bright meteors had been recorded on all-sky cameras of the Spanish Meteor Network and activity of the Kappa Cygnids appeared to peak around Aug. 13 00h UTC, during the peak of the Perseids, but lasted for several days.

At the time, a group of 12 researchers were deployed over California and the Pacific Ocean in a Gulfstream GV jet to prepare for an observing campaign for the rare Aurigid meteor shower two weeks later, on Sept. 1. Sure enough, while watching the video tapes that were recorded during this test flight, numerous slow Kappa Cygnid meteors were discovered.

Amazingly, for just trying, we already got something out of this practice campaign. The Kappa Cygnids had last erupted in 1993, and perhaps also in 1999, and the 2007 return was completely unexpected. The new observations of the Kappa Cygnids may shed light on the origin of this shower.

Unlike the Aurigids, the Kappa Cygnids do not have a known parent body, and no predictions can be made yet to forecast the next return. They move in short, 6 to 12-year orbits and are much younger than the 2,000-year-old Aurigids.

August 28 Lunar Eclipse
Last night, August 28, there was a lunar eclipse here in California. Predictions were widely circulated when the Moon would move into the shadow of Earth. Sure enough, I watched, delighted to see the last sliver of unobstructed sunlight disappear when the Moon, exactly on time, moved completely into the shadow. I spent the night taking pictures of the fading Moon, watching the sky become even darker.

Will meteor showers become as predictable as lunar eclipses in the future? Early astronomers in the ancient Orient and China predicted lunar eclipses after noticing periodic patterns in their return. Precise predictions became possible centuries ago once Newton formulated the law of gravity. The application of Newton's law to predicting meteor showers is something we have been able to do well only very recently. In the past ten years we have had some success in predicting the return of unusual showers by calculating how the planets hustle the dust trails in and out of Earth's path.

So far, the Aurigid shower on September 1 is our most ambitious prediction. The meteors date from 2000 years ago, four times farther back in time than the previous record holder, the year 2000 Ursid outburst, which dated from the time of Columbus.

Will the Aurigid shower return as predicted between 4 and 5 PDT in the early Saturday morning of September 1? Will it be visible from western parts of the USA and Mexico? Again, we're flying to observe based upon our predictions. Only by making these observations can we improve our methods, and make forecasting meteor showers as reliable as predicting eclipses.

Please join us in making observations. We invite that the general public to submit digital images and camcorder pictures of the Aurigid meteors.

(Peter Jenniskens is a meteor astronomer at the SETI Institute's Carl Sagan Center.)