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According to calculations by Dr David Asher of the Armagh Observatory and Robert McNaught of the Anglo-Australian Observatory, a Leonid meteor storm is expected to be visible this year from Northern Ireland, with a peak during the early hours of 19th November. The peak rate could be more than 1000 shooting stars per hour for up to an hour either side of 04:00.

Dust grains emitted by comet Tempel-Tuttle as it swings past the Sun once every 33 years produce the Leonid meteors. This comet revolves around the Sun in the opposite direction to the Earth, so that when the Earth crosses the trail of debris - which is composed of a number of dense discrete streams of dust particles - the dust grains enter the atmosphere at very high speeds, about 160,000 miles per hour. Most of the dust grains are very small, vaporizing in a few seconds at heights of 50 or 60 miles as they speed into the Earth's atmosphere, producing the familiar streaks of light.

Leonid dust trails in 2002
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Leonid dust trails 2002

McNaught/Asher estimates for years 2000 to 2006

The dust particles move in very similar orbits around the Sun, but by perspective they seem to come from a single point in the sky known as the radiant. The radiant lies in the constellation Leo, hence the term Leonids. Leo will be fairly high in the south-east during the expected peak of the shower, however, the nearly full Moon will also be quite high in the western sky and its light may wash out the fainter meteors. The gas giant planet Jupiter will be shining brightly close to the radiant this year.

Meteor storm prediction had until recently been a rather uncertain science, but the techniques developed by David Asher and Robert McNaught have enabled storms to be forecast accurately to within a few minutes. This year, their calculations indicate two storms: the first, peaking at 4:00 am being visible from the UK and Ireland; the second, peaking at 10:36 am being visible from north America.

Those who wish to observe these meteors are advised to wrap up warm, find a clear dark site, and to look towards the northeast or southeast away from the glare of the Moon. The usual annual background Leonid meteor shower occurs this year from 15th to 20th November peaking on the night of 17/18 November and it is best observed after midnight.

Prof. Mark Bailey or John McFarland at the Armagh Observatory.
Tel.: 028-3752-2928; FAX: 028-3752-7174;
e-mails: meb@star.arm.ac.uk and jmf@star.arm.ac.uk

See also:
Armagh Observatory Leonid Pages
Astronomical Society of Australia

Last Revised: 2002 November 8th
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