Perseids Will Peak on August 11

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.

Original Source: Sky and Telescope News Release

Get Ready for the Perseids

Image credit: ESA
The annual Perseid meteor shower is coming, and astronomers say it could be unusually good this year.

The shower begins gently in mid-July when Earth enters the edge of a cloud of debris from Comet Swift-Tuttle.

Dust-sized particles will hit our atmosphere and appear to streak across the night sky. At first there will be just a few meteors each night, but then the rate will build. The Perseids are visible between 23 July and 22 August but, by 12 August, at the peak of the shower, skywatchers can expect to see possibly 80-100 meteors per hour if skies are clear.

This is a good year for Perseids for two reasons. First, the Moon is new in mid-August, so moonlight will not spoil the show as much as it would have done last year, had the sky been clear! Second, in addition to the usual shower on 12 August, there might be an extra show of meteors late in the evening of 11 August caused by a ?filament? of dust drifting across Earth’s orbit for the first time.

This filament, like all the dust in the Perseid cloud, again comes from Comet Swift-Tuttle. The difference is, the filament is relatively young. It ?boiled? off the comet in 1862. Other dust in the cloud is older (perhaps thousands of years old), more dispersed, and responsible for the month-long shower that peaks on 12 August. The filament will eventually disperse, too, but for now it retains some of its original ribbon shape.

According to current predictions, Earth will move through the filament on Wednesday, 11 August at 23:00 CEST. This will produce a surge of mostly faint meteors over Europe and Asia. Because of the way Comet Swift-Tuttle?s orbit is tilted, its dust falls on Earth’s northern hemisphere. Meteors appear to stream out of the constellation Perseus, which is barely visible south of the equator.

Later that night and into the early morning hours of Thursday, 12 August, observers will see the ?traditional? Perseid peak caused by the older dust from Swift-Tuttle. The best time to look for these traditional Perseids is during the hours before dawn on Thursday.

How to observe the Perseids
The best way to observe them is to look towards the northeast after dark. They appear to originate from the constellation of Perseus which at midnight lies just below the easily recognisable ‘W’ of Cassiopeia.

Try looking around 22:00-23:00 CEST on Wednesday, when Perseus is hanging low in the eastern sky. You won’t see many meteors then, but the ones you do see could be memorable. On Thursday morning, the highest frequency of meteors is likely just before dawn.

Original Source: ESA News Release