Perseid meteor shower on view Aug. 11

By Roy Gephart, Special to the Tri-City HeraldAugust 5, 2012 

RICHLAND, Wash. -- The Perseid meteor shower peaks during the night of Saturday, Aug. 11 in the summer's most popular display of "shooting stars."

Under a dark sky, tens of meteors are visible each hour. During some years, I've counted more than 300 meteors in a single night of peak activity.

If you can't escape the glare of city lights, watch for meteors from the darkest corner of your backyard, a park, or schoolyard.

On Saturday night, you also may choose to drive north of Richland to the LIGO (Laser Interferometer Gravitational-wave Observatory) Hanford facility where families will gather to observe meteors, learn to identify summer constellations, and explore the heavens using telescopes provided by members of the Tri-City Astronomy Club.

That event runs from 8 p.m. to 1 a.m. For more information and directions, search online for "LIGO Hanford."

Meteor observing requires patience -- like fly fishing for brown trout in a swift mountain stream or sighting the red crest of a pileated woodpecker. However, effort pays off.

Though the average Perseid shines with the brightness of a star in the Big Dipper, the most luminous meteors can slice the star-lit sky in a sizzling trail of yellow light.

This year, we're fortunate that the shower peaks on a weekend, making it convenient to stay up late, drink lots of caffeine to stay awake, and judiciously tell your spouse that you're spending the night with friends somewhere in the desert amongst the sagebrush and bluegrass to count meteors.

However, you'll need to build credibility before delivering such a message. So as soon as possible, begin sharing your fascination with meteors, leave astronomy books scattered across the coffee table, and start tucking star charts under your arm.

On the other hand, why not ask your partner to just come along? Pack a midnight snack, chill your favorite white wine, and toss a few lounge chairs into the car. You can turn an evening of meteor observing into a memorable date.

Where do most meteors come from?

The inner solar system is laced with dust to pebble size rocky material released from ancient comets that journeyed billions of miles before slinging around the sun to return into the frigid reaches of deep space.

During the Earth's yearly journey around the sun, it plows through this comet rubble.

When this material slams into the upper atmosphere, air friction quickly incinerates these small fast moving particles. This creates the luminous trails of meteors we see crossing the night sky.

The first few Perseid meteors become visible starting in early July. The last ones continue to be sighted through late August.

However, close to Aug. 11 each year, the Earth orbits through the thickest concentration of particles once released from a comet discovered in 1862 by the two American astronomers Lewis Swift and Horace Tuttle. The comet is named Swift-Tuttle.

Scientists estimate that each day the Earth gains 1,000 tons of cosmic debris from asteroids grinding against each other and comets shedding their rocky litter.

So, take heart that even the Earth is gaining weight as it enters middle age.

If Saturday night is not convenient for observing, large numbers of meteors will also be visible on Friday and Sunday nights.

The best time to watch for Perseids is after midnight. This is when the shower's radiant lies highest in the northeast sky.

On Saturday night, the waning moon rises about 1 a.m. Moonlight will hamper our view of faint meteors but not the brightest ones. Sunday night offers one extra hour of moonless sky.

Though written records of Perseid meteors date back for more than 2,000 years, their origin remained a mystery until the discovery of comet Swift-Tuttle.

We now know these streaks of light originate from solid particles formed during the dawn of our solar system. These particles later rode the sun-lit dusty tails of icy comets before capturing our wonder in the summer's night sky.

* Roy Gephart is a retired environmental scientist and an avid amateur astronomer. He can be reached at roygephart@ yahoo.com.

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