By: Tom Wickersham

Annual Perseid Meteor Shower Viewing

Has all this discussion about a "dark sky ordinance" peaked your curiosity? Are you not quite sure what you're missing? If so, here's your chance to watch the night sky come alive.

Explorit Science Center's Astronomy Club will be hosting their annual Perseid Meteor Shower party this Wednesday, August 12, 8:30 p.m. at Fairfield Elementary. Known by the members of the club as the "Big One," the Perseid Meteor Shower has proven to be a great opportunity for meteor gazing.

Every year, about August 12, the Earth enters an area of its orbit around the sun that lies close to the orbit of Comet Swift-Tuttle. The debris from this comet creates the Perseid Meteor shower, the most popular and most famous of all showers.

As we watch the late night sky in mid August, this debris--mostly particles the size of grains of sand--will be traveling 30 or 40 miles per second and vaporizing into incandescent streaks as they incinerate in Earth's protective blanket of air. This shower is notable for its constancy and for the rapid movements of the meteors as they streak through the sky. Approximately 45 percent of the meteors leave "trains" or smoke-like trails that persist for a few seconds.

The Perseid meteor shower gets its name from the location of the radiant of the shower in the constellation Perseus. The radiant, however, is an optical illusion appearing to be the point in the sky from which the meteors originate. The Comet debris that enters our atmosphere is traveling in parallel paths around the sun, but from our perspective, it seems the meteors are "radiating" from one spot in the sky to all other areas of the sky.

The phenomenon is somewhat similar to standing between a pair of railroad tracks and looking down them to one point on the horizon. The tracks, like the paths of the comet dust, appear to radiate in two directions toward you, but in fact are parallel lines.

That meteor showers were the result of comets was surmised, though not proven, by American Edward Claudius Herrick in 1838, who investigated historical accounts of meteor displays and actually documented the history of the Perseid shower as a periodic event.

This Connecticut amateur ultimately had to concede that two other investigators had discovered the annual nature of the Perseid shower independently (and earlier) in Brussels and Cincinnati. Herrick's evidence, however, was more complete and compelling.

We should keep in mind that in Herrick's time, most scientists argued that meteors in general were phenomena of weather and were not originating in outer space. In fact, the word "meteor" refers to weather-based phenomena.

So don't miss out on this stellar event at Fairfield elementary. It's free and open to all. There is a big grassy area for chairs and blankets and an area of asphalt for telescopes and other items. For more information call Explorit at (530) 756-0191 or read Explorit's Astronomy Club newsletter on-line at www.dcn.davis.ca.us/GO/EXPLORIT.

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Explorit Science Center is located at 3141 5th Street in East Davis. The current exhibition is The Way the Ball Bounces: The Science of Toys and Games. Public hours are Saturday from 11:00 a.m. to 4:30 p.m., Sunday from 1:00 to 4:30 p.m., and Tuesday through Friday from 2:00 to 4:30 p.m. Regular admission is $3; members, teachers (with school ID) and children under 4 are free.