Streaking, peaking Perseids face a moonlight washout

August 11
NASA explains how the brightness of the supermoon will affect the annual Perseid meteor shower. (ScienceAtNASA via YouTube)

 

For the peak of the annual Perseid meteor shower, our eyes will battle the moon’s waning brightness on Tuesday evening into Wednesday morning – two days after a full moon. (The moon rises at 9:15 p.m. on Tuesday night and sets at 9:44 a.m. the next day, according to the U.S. Naval Observatory.)

During the usually intense peak of the Perseids, this year’s lunar glow creates so much light that the smaller shooting stars become invisible and the bright ones – at best – hard to see. The flow of the Perseid meteors runs from July 13 to August 26, according to the American Meteor Society (amsmeteors.org). (In practical terms, however, the Perseids slow to a drip several days after peak.)

In a normal year, the Perseids usually peak at around 100 meteors an hour. For the 2014 shower, preliminary Perseid activity studied by the International Meteor Organization (imo.net) indicates between 5 and 10 shooting stars each hour between July 13 and July 30.

For last year’s shower, activity reached 20 meteors each hour around Aug. 5 and shot up to near 40 meteors an hour at Aug. 10. It peaked on Aug. 12/13 with observers counting nearly 120 an hour. Sky gazers saw about 50 Perseid meteors an hour on Aug. 14 and about 20 an hour on Aug. 16.


(Sky & Telescope magazine)

Bill Cooke, NASA meteor expert, holds out hope that for backyard meteor hunters, the Perseids usually toss in a few more fireballs than other large showers, he says.

To observe these Perseids, Alan MacRobert, a senior editor at Sky & Telescope magazine, suggests to relax, be patient and let your eyes adapt to the dark. Even with the moonlight, he says, gazers may see any of the brighter shooting stars at least every several minutes during peak.

Meteors are space dust leftover from comets gone-by. In the case of the Perseids, it’s periodic Comet Swift-Tuttle (109/P.) Comets are huge space snowballs freckled with sand-size dirt, and as they swing by the sun in our solar neighborhood, the space debris leaves a trail of dust.

On its own orbit around the sun, Earth slogs through these comet trails of trash and the dust strikes Earth’s atmosphere – where the dust incinerates. That’s when we see the shooting stars.

The Perseid meteors appear to emanate from the constellation Perseus, which rises in the northeastern heavens at around 11 p.m. now. Certainly you may observe meteors from all directions, but in generally they appear to come from Perseus.

The Washington connection: Comet Swift-Tuttle was discovered in two places independently by astronomers Lewis Swift and Horace Tuttle in July 1862. Tuttle joined the U.S. Naval Observatory here and is buried in an unmarked grave in Oak Hill Cemetery, Falls Church.)

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