(This 749th Buffalo Sunday News column was first published on August 7, 2005.)
If the weather cooperates, Thursday and Friday this week should be good nights to witness a meteor shower.
The Perseids, so named because these meteors seem to radiate across the sky from the constellation Perseus, should be most evident on those two evenings. If you are fortunate, you might see a meteor every minute or two. This is the time of maximum activity but the full period for Perseid observations this year extends from July 17 to August 24.
The best times for observations will be from 11 p.m. until 4:30 a.m. on August 11/12 and 12/13. On each of those nights Perseus will move from the northeastern skyline below Cassiopeia higher into the heavens and toward the east. The waxing moon will set in the southwest before 11:30 p.m. on both nights and thus will provide little light interference.
According to Gary Kronk, from whom much of the information of this column is drawn, "To best observe the Perseids lie outside in a reclining lawn chair with your feet pointing somewhere between the southern and eastern horizon and look straight up. Do not look at the constellation Perseus, because then meteors directly in front of you will not seem to move much and fainter ones might be missed. When you see a meteor, mentally trace it back and if you arrive at Perseus it is probably a Perseid." This retracing is appropriate because many meteors from other sources may also appear.
It is important to add that you should seek a place to observe that has as little light pollution as possible, not an easy task in this region. Because even in the surrounding countryside every farm seems to have its sodium light burning brightly, I have found no good spot near Buffalo. (I invite readers to inform me of their favorites.) Further afield, on Thursday August 11th, weather permitting, Buffalo Astronomical Association member Bill Aquino tells me that their observatory at the Beaver Meadow Nature Center on Welch Road in Java will be open from sunset through the night. Visitors should dress warm, bring a lawn chair, blanket, mosquito repellent, thermos and a snack.
For those not familiar with the terminology, meteors or "shooting stars" appear as fast-moving white or less often blue-white, red or even green streaks across the sky. Technically meteors are visible meteoroids, which are tiny, usually sand-sized particles that orbit the sun. Our space vehicles often return with their outer surface pitted by collision with these tiny objects. Astronomers believe that meteoroids were produced by comets and the Perseids have been associated with Comet Swift-Tuttle.
Obviously you cannot detect a grain of sand flying through space but, when such objects come within 60 to 80 miles of our Earth, friction with our atmosphere causes them to glow and thus become visible.
Occasionally larger meteors do not burn up completely and fall to Earth. These are called meteorites. In 1992 one was seen and filmed across several eastern states. It broke up into many fragments, one of which hit the trunk of a woman's car outside her Peekskill, NY home. She found a 26-pound meteorite lying beside the damaged car.
Meteorites are not uniformly distributed through space and our planet passes through two areas each year where such dust has accumulated. Each November, when observing conditions are far less comfortable, we pass through another grouping called the Leonids.
The first known Perseid meteor record comes from China in 36 A.D. and they have been recorded fairly regularly ever since. Since 1839 when German astronomer Eduard Heis counted 160 meteors per hour, observers have kept track of the numbers seen each year. The highest hourly rate was about 500 in 1993 when parent Comet Swift-Tuttle was nearby.
The International Meteor Organization (IMO) keeps careful records of meteor activity and local observer Bill Watson has been a regular contributor. He shared with me his August 2003 IMO reports and I was surprised to learn that in nine hours of observations then only about half of the meteors he saw were Perseids.
Watching meteors streak across the sky is an awe-inspiring experience. This week offers a chance to partake of this astronomical feast.-- Gerry Rising