Armagh Observatory, 8 November 1999:

According to calculations by Armagh Observatory astronomer Dr David Asher, the Leonid meteor shower is expected to reach a peak during the early hours of 18th November, with a rate of more than 1000 shooting stars per hour for up to an hour or two either side of 02:00 am. These meteors are produced by dust grains given off by comet Tempel-Tuttle as it orbits the Sun once every 33 years.

This comet revolves around the Sun in the opposite direction to the Earth, so 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 run into the atmosphere, producing the familiar streaks of light.

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. This lies in the constellation Leo, hence the term Leonids. Leo will be above the north-north-eastern horizon during the expected peak of the shower, and the Moon will have just set making viewing conditions in 1999 quite good provided that the sky is clear.

Those who wish to observe these meteors are advised to wrap up warm, find a clear dark site, and to look in the general direction of the radiant, roughly towards the north-east after midnight.

FOR FURTHER INFORMATION CONTACT: David Asher ( or John McFarland ( at the Armagh Observatory. Tel.: 028-3752-292.

See also: Leonid Meteor Page

Last Revised:i 8th November 1999
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