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Last Updated: Thursday, 12 August, 2004, 08:25 GMT 09:25 UK
Moonlight 'will not spoil' meteor show
Perseid meteor, Nasa
The light show will not be spoilt by moonlight this year
The annual Perseid meteor shower, which peaks on 12 August, could provide a "spectacular" show this year, according to Irish astronomers.

Sky watchers were hoping to witness a surge of meteors just before dawn on Thursday.

The meteors peak on Thursday 12 and Friday 13 August after 2330 BST and should be visible with the naked eye from a dark location.

Stargazers were left frustrated on Wednesday night as cloud blocked any chance of seeing the spectacle.

Meteors are streaks of light in the sky caused by blazing pieces of dust drawn into the Earth's atmosphere from near space.

The Perseids are caused when the Earth passes through debris shed by Comet 109P/Swift-Tuttle. This comet travels through the inner planets every 130 years, most recently in 1992.

The annual celestial event is a firm favourite of sky watchers. In the past, hundreds of meteors per hour have been observed flaring brightly in the night sky.

A spokesman for the Irish Astronomical Association said conditions this year were particularly favourable.

He added: "Some experts also think that activity will be unusually high this year.

"Activity will be quite high on the nights of the tenth, eleventh and twelfth of August with best rates in the early hours of 12 August, and a possible early burst of activity early on the previous evening.

"You'll see most meteors by looking nearly overhead, but to get a proper view you must get away from all the light pollution of our towns and cities.

"If there's a lot of artificial light nearby, you might see only about one tenth as many meteors as if you were out in a dark rural sky."

Last year's event was marred because the Moon was nearly full, drowning out the glow from the Perseids.

Astronomers think a faint, extra surge of meteors may be visible on 11 August at 2200 BST due to a filament of dust that boiled off 109P/Swift-Tuttle in 1862 and is only now crossing the Earth's orbit.

If predictions are correct, another surge might occur just before dawn on 12 August due to the influence of Jupiter's gravity concentrating some of the fine comet dust.

The Perseids are so called because tracing their tails back in the night sky mostly leads to the constellation Perseus.

This contains a point called the Perseus radiant - the perspective point from which the meteors would appear to come if they could be seen approaching from interplanetary space.

The Perseids are sometimes called the Tears of St Lawrence because the saint's feast day falls on 10 August.

The dust itself consists of particles that are roughly the size of a match head - or a dried pea - that are travelling at around 50km per second. As they enter the Earth's atmosphere, they burn up with a short-lived burst of light, heat and ionisation.

Perseids set for sky show
11 Aug 03  |  Science/Nature
Skywatchers treated to celestial display
13 Aug 02  |  Science/Nature

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