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ASTRONOMY / PERSEID METEOR SHOWER : Annual Light Show Is Expected to Be the Best in Years

TIMES SCIENCE WRITER

A celestial show that has delighted sky-watchers for the past 1,900 years will paint the northeastern sky with meteors this weekend in what is expected to be the best Perseid Meteor Shower in several years.

The shower peaks every year on Aug. 10 or 11, when the Earth crosses a broad stream of debris left over from the passage of Comet Swift-Tuttle. But this year, for the first time since 1988, the meteors will streak through the Earth’s atmosphere on moonless nights. That will make the specks of vaporizing dust easier to see.

Astronomers around the world will lie on their backs from midnight to dawn Sunday and Monday in a continuing effort to define the size and timing of the shower. In 1988, 157 observers took part in an international survey and reported seeing 32,041 Perseids, according to Paul Roggemans of Belgium, who is coordinating this year’s effort.

The best viewing will begin at midnight Saturday, and observers with a clear view of an unclouded sky should be able to see about 50 meteors every hour, according to the Reuben H. Fleet Space Theater & Science Center in San Diego. The shower is expected to peak in the predawn hours Monday.

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Viewers need no special equipment; binoculars and telescopes limit the area of the sky that can be observed, and a wide field of view is necessary to see as many meteors as possible. The tiny specks of dust will glow brilliantly as they burn up while streaking through the Earth’s atmosphere at more than 35 miles per second.

The Perseids are named for the constellation from which they appear to be coming, and they have been zipping through the summer sky at least since Chinese observers first recorded them July 17, AD 36.

For years the Perseids were known as the “Tears of St. Lawrence” because they were especially bright when the Spanish martyr was killed on Aug. 10, 258.

Because it was not reported to be observed every year, it was not until 1835 that astronomers recognized the Perseids as an annual event. The shower has been observed every year since, though initially no one knew the origin of the meteors.

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In 1866, the astronomer Giovanni Schiaparelli determined that the Perseids follow a course that is almost identical with the orbit of the periodic comet, Swift-Tuttle.

With that discovery came the end of the puzzle over the sky’s own version of “brilliant pebbles.” They are nothing but cometary dust, ending their sojourns in a blaze of glory.


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