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The Leonid meteors are set to make their annual return over the interval from 13th to 22nd November. The meteors, or shooting stars, are produced by debris from periodic comet Tempel-Tuttle, which makes a fly-past of the Sun approximately every 33 years. During each close approach to the Sun, the comet sheds a stream of dust and small particles. These streams of particles can remain intact for centuries before dispersing.

Each year the Earth encounters the ancient broad stream of material during mid-November. This year is rather unusual, though, in that the Earth will come close to the edges of two of the more coherent dense dust trails, resulting in two main meteor showers, one on the Thursday, 13th November and the other on Wednesday, 19th November. The western United States and the Asian Pacific coast region will be favoured on the 13th November, while the east coast of America will be favoured for the display on the 19th.

According to Armagh astronomer, Dr David Asher, and collaborators, the first shower will be produced by material emitted from the comet in 1499. This dust stream contains a number of dense trails which will give rise to multiple showers between 1:15pm and 6:20pm. The Moon will be closer to this stream but the lunar impacts will not be observable from the Earth as they will occur on the Moon's far side.

The second shower, on the 19th November, resulting from an encounter with the dust trail emitted in 1533, will produce meteor activity for a few hours centred around 8:00am. As with the shower six days earlier, activity may under ideal observing conditions exceed 100 meteors per hour, although it is unlikely that many meteors will be visible from Northern Ireland owing to the rapid brightening of the dawn sky around that time.

Northern Ireland viewers may have their best views between 00:50am and 01:30am on Thursday 20th November when the Earth encounters the dust trail emitted by Tempel-Tuttle in the year 1333. It was material emitted by the comet in 1333 that led to the rare display of a shower of bright meteors, known as "fireballs", on the early morning of 17th November 1998. However, peak rates may be no more than 20 meteors per hour, but the meteors may be somewhat brighter than for most of this year's other Leonid encounters.

Observers are advised to wrap up in plenty of layers of warm clothing and view from a dark, preferably elevated, site. Although the meteors radiate from the constellation Leo, which may be seen in the East after midnight, they can appear in almost any part of the sky. If the Moon is prominent at any time, try to view the sky with your back to the Moon, or from within the shadow of a building. It may be worthwhile observing the Leonids after midnight on as many days as possible between 13th and 22nd November in case of unexpected additional activity.

FOR FURTHER INFORMATION CONTACT: David Asher or John McFarland at the Armagh Observatory, College Hill, Armagh, BT61 9DG. Tel.: 028-3752-2928; FAX: 028-3752-7174; djaarm.ac.uk; jmfarm.ac.uk; Website: http://star.arm.ac.uk/

See also: Leonid Meteors Site

Last Revised: 2003 November 7th
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