[meteorite-list] Perseid Meteors to Peak Late on the Night of August 11th

Tue Aug 10 11:16:39 EDT 2004

Sky & Telescope
Cambridge, Massachusetts

Contact:
Alan MacRobert, Senior Editor

Press Release: August 5, 2004

Perseid Meteors to Peak Late on the Night of August 11th

The Perseid meteor shower, an annual celestial event beloved by millions of 
skywatchers around the world, returns to the night sky this coming week.

Sky & Telescope magazine predicts that the Perseid shower will reach its peak 
late Wednesday night and early Thursday morning, August 11-12. The rate of 
activity should pick up steam after midnight until the first light of dawn. 
North America, especially the West and Hawaii, is optimally positioned to catch 
the best of the shower.

An observer under a dark sky might typically see more than 60 Perseids per hour 
between midnight and dawn. Since the waning crescent Moon will be only three 
days from new at the time of shower maximum, posing minimal interference with 
the view, this is an opportune year for watching them.

You'll need no equipment but your eyes. The darker your sky, the better - any 
artificial light pollution in your sky will reduce the number of meteors that 
are visible. But even if you live in an urban or suburban area, you have a good 
chance of seeing at least some meteors. Find a dark spot with a wide-open view 
of the sky. Bring a reclining lawn chair, insect repellent, and blankets or a 
sleeping bag; clear August nights can get surprisingly chilly.

"Go out after about 11 p.m. or so, lie back, and watch the stars," says Sky & 
Telescope senior editor Alan MacRobert. "Relax, be patient, and let your eyes 
adapt to the dark. With a little luck you'll see a 'shooting star' every couple 
of minutes on average."

Perseids can appear anywhere and everywhere in the sky. So the best direction to 
watch is wherever your sky is darkest, probably straight up. Faint Perseids 
appear as tiny, quick streaks. Occasional brighter ones may sail across the 
heavens for several seconds and leave a brief train of glowing smoke.

If you trace each meteor's direction of flight backward far enough across the 
sky, you'll find that your imaginary line crosses a spot in the constellation 
Perseus, near Cassiopeia. This is the shower's radiant, the perspective point 
from which all the Perseids would appear to come if you could see them 
approaching from interplanetary space. The radiant is low in the north-northeast 
before midnight and rises higher in the northeast during the early-morning hours.

Don't give up if it's cloudy Wednesday night. The Perseid shower lasts for about 
two weeks, with good rates in the predawn hours of August 10th through 15th. 
This year the ever-thinning Moon becomes less of a problem with each passing 
night. Far fewer meteors will appear before midnight, even on the night of the 
shower's maximum, because the radiant is then quite low in the sky. The radiant 
is always low or below the horizon for Southern Hemisphere countries like 
Australia, New Zealand, and South Africa, where few, if any, Perseids can be seen.

The Perseid meteoroids are tiny, sand- to pea-size bits of rocky debris that 
were shed long ago by Comet Swift-Tuttle. This comet, like others, is slowly 
disintegrating as it orbits the Sun. Over the centuries, its crumbly remains 
have spread all along its 130-year orbit to form a sparse "river of rubble" 
hundreds of millions of miles long.

Earth's own path around the Sun carries us through this stream of particles 
every mid-August. The particles, or meteoroids, are traveling 37 miles per 
second with respect to Earth at the place where we encounter them. So when one 
of them strikes the upper atmosphere (about 50 to 80 miles up), it creates a 
quick, white-hot streak of superheated air.

For several years in the early 1990s the Perseids performed spectacularly, 
flaring with outbursts of up to hundreds of meteors per hour. The particles 
responsible for these outbursts were probably shed during Comet Swift-Tuttle's 
swing by the Sun in 1862.

Astronomers Esko Lyytinen of Finland and Tom Van Flandern of Washington, DC, 
have alerted skygazers to the possibility that this "extra" Perseid peak could 
make a comeback in 2004. They predict that this year, the rubble trail released 
in 1862 will pass just 200,000 kilometers (125,000 miles)) inside Earth's orbit 
on August 11th, just as observing conditions become optimal for meteor watchers 
in Eastern Europe and eastern North Africa eastward to central Russia, India, 
and western China.

Will the Perseids "storm" in 2004? There's only one way to find out: Get outside 
and watch the show!

More about the Perseid meteors — and how to watch and photograph them — appears 
in the August 2004 issue of Sky & Telescope magazine and online in the articles 
listed at the end of this press release.

Sky Publishing Corp. was founded in 1941 by Charles A. Federer Jr. and Helen 
Spence Federer, the original editors of Sky & Telescope magazine. The company's 
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