StarWatch for the greater Lehigh Valley

AUGUST  2001


258   AUGUST 5, 2001:     PA Fireball was Big
The meteorite shower that pelted North Central, PA on Monday evening, July 23rd was probably one of a dozen events which occurred on that date. The Earth is continuously being bombarded by rocks from outer space, but most of them land over water or in sparsely populated areas where witnesses are few. This event was certainly much bigger than most, something that might have killed people or animals had they been in the path of the oncoming fragments. Sonic booms louder than thunder, a residual dust trail from a detached main body, shock fronts of air powerful enough to move curtains, open doors, and push over corn; and vibrations from sonic booms that caused pictures to fall off walls and break windows are good evidence that something big happened. There were a lot of scared folks that evening and rightfully so. Keep in mind that what happened is not related to the annual showers of meteors which can be seen in our skies. Meteorites strike Earth as a result of wayward asteroids which cross the Earthís orbit. The flash of light left by meteors is created by debris lost by comets as they pierce the atmosphere of Earth. It is the larger debris from the asteroid belt which makes it to the surface to become meteorites. There has never been a witnessed fall of a meteorite produced by a meteor shower. Witnessed meteorite falls, where the rock was touched or picked up shortly after it was seen to hit the ground, were found to be cold; some were even covered by frost. The Perseid meteor shower is coming. More information about the yearís best meteor shower will follow next week or read ahead at the web site below.

259   AUGUST 12, 2001:     Perseid Week
During this week Perseid meteors "fly," and hopefully with better weather, it might just be a good time to get outdoors and observe the show. Sunday into Monday misses the peak activity by one day, but you can catch Perseid meteors through August 22nd if you are persistent. The moon begins the week at third quarter, rising later each night and diminishing in brightness until it is new on August 19th. Unfortunately, the start of the week sees the moon close to the location in the sky from where Perseid meteors are emanating. Your best bet will be to lie out in a reclining lawn chair, starting your observations after 11 p.m. Point the foot end of the chair towards the south and observe directly overhead. This will help to minimize any distractions caused by moonlight while allowing the observer to catch meteors that have longer paths. As you watch for Perseids, you'll notice a position in the sky from which these meteors appear to be diverging. This area is called the radiant, and it is located between the top of Perseus, the Hero, and the bottom of the "W" which is Cassiopeia, the Queen. Print a map of this region of the sky by going online to this week's StarWatch at the web address below. Annual meteor showers, such as the Perseids, result from debris discarded by comets as they circle the sun. The orbit of Comet Swift-Tuttle comes close enough to Earth's orbit so that dust particles, which were once part of Swift-Tuttle's tail, pierce the atmosphere, causing the air to glow creating Perseids. It is this cylinder of incandescent air, about one mile in diameter and tens of miles long, that we perceive as a meteor. We never observe the glowing particle, which is about as small as a grain of sand.

Perseid Meteor Map

260   AUGUST 19, 2001:     Thunder in the Canyon
For individuals who enjoy looking up, the heavens present numerous opportunities for diversion. When I first came to Chaco Canyon, near Nageezi, New Mexico in mid-May, the nights were always radiantly clear and the temperatures near or below freezing. Physically, my observing companions and I were taxed to the point where we hoped for a cloudy evening. Our prayers were finally answered. The summer monsoons abruptly started on June 22nd. The monsoonal model works this way. Weather patterns drive moisture-laden air inland from the Pacific or Gulf of Mexico. As this moisture rises over higher terrain, it cools and its ability to hold water decreases. This causes clouds to form, and astronomers get a break. Well, not always... If the pattern is really active, as it can be in Chaco, the canyon can be surrounded by dozens of thunderstorms by late afternoon or early evening. Since the air is clear and the rain minimal, driving to a slightly higher vista can give you a panorama of Earth continuously being pounded by bright flashes of electricity. On one such evening, July 9th, the canyons really rocked. I observed the development of a supercell, a storm so huge that it created its own weather. It happened over North Mesa in just 30 minutes. The ground warmed by the dayís sun caused the atmosphere to lift so rapidly that air was driven across the canyon into the developing tempest. The canyon air with its higher moisture content continued fueling the storm. Within minutes, clouds over South Mesa began to elongate and shear into the stormís boundary. The night was lit up by magnificent pyrotechnics. Astrophotography switched to lightning photography. And again, no one slept!

261   AUGUST 26, 2001:     Lightning Beetle
A long time ago when the Holy Ones were deciding how all would be in harmony, there was a lovely white creature called Lightning Beetle. He was chosen to place the stars in the sky. After sundown, Beetle would begin his trek in the East where darkness arrived first. He carried a large bag filled with sparkling quartz, positioning each stone carefully in the sky, and polishing any that had become dusty during the previous night. Invisibly he would zigzag across the heavens, placing the final stars in the west where the light of day remained the longest. The People and creatures of the Earth were filled with wonderment over the beauty which Beetle created each night, and they told him how special and good he was at his task. At first Beetle responded modestly, saying that no creature was more important than any other. He continued to perform his task with humility. But gradually the praises that were bestowed upon him began to make Beetle think that he was more important. The Holy Ones watched without comment. Then one evening while listening to these compliments, Lightning Beetle forgot to notice the setting sun. It became darker and no stars appeared. Realizing his mistake, Beetle grabbed his sack and scurried to place the stars in the sky. But a number of the crystals were dusty, so some stars did not shine with their original brightness. Because he was white, everyone could see him as he moved back and forth. As a consequence, the Holy Ones decided to make Lightning Beetle black like the night and stinky. Thereafter, he could place the stars in a darker sky and never be accidentally seen again, so says the SW native legend. Source: Liz Churchill, Utah Valley State., Orem... See Lightning Beetle at the web address below.

[Lightning Beetle]
Liz Churchill, ethnonaturalist at Utah Valley State in Orem, holds Lightning Beetle in her hand. More commonly this insect is known as the Bombardier Beetle or Brachinus crepitans. Digital photography by Gary A. Becker.

August Star Map

August Moon Phase Calendar