Tiny meteors will put on a spectacular show tonight

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A SPECTACULAR display of celestial fireworks is expected tonight as a stream of meteors ploughs through the Earth's atmosphere to generate what could be the best gallery of shooting stars for 33 years.

Astronomers at the Armagh Observatory in Northern Ireland calculate that the most intense bombardment should be at about 2am on Thursday but the shooting stars may be visible at any time of night.

A Leonid meteor is typically not much bigger than a grain of sand but when it hits the atmosphere at about 45 miles per second - 40 times the speed of a rifle bullet - the intense heat generated appears as a fiery streak across the sky.

At such speeds, a meteor collision could impart enough energy to cause serious damage to satellites. In addition, the meteors generate clouds of electrically charged particles that can short-circuit a satellite's electrical instruments.

The European and Amer-ican space agencies have warned satellite operators to turn their spacecraft away from the shower. The delicate mirrors of the Hubble space telescope will also be shielded.

The meteors are caused by dust and debris trailing behind Comet Tempel- Tuttle as its solar orbit takes it past the Earth about every 33 years.

The last time Earth passed through the centre of the meteor trail was in 1966 when a spectacular storm peaked with up to 40 shooting stars a second streaking through the sky. Previous meteor storms were in 1799, 1833 and 1866.

David Asher, an astronomer at the observatory, discovered that there are several meteor trails the Earth can pass through and the current activity is caused by a trail created by the comet's pass in 1899.

It is difficult to gauge the number of meteors that will be visible and whether they will reach the 1,000 sightings an hour for the meteor shower to be classified as a storm. "It's marginal as to whether the meteor activity will reach storm level in 1999 but, however strong it turns out to be, European longitudes are ideally placed for observing the outburst," Dr Asher said.

The Leonids can appear at any part of the sky but if their path is plotted they all appear to emanate from the constellation of Leo - which gives them their name.

Nasa scientists will observe the meteors from an aircraft above Israel in a region where the storm is expected to be seen at its most intense.

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