LEONID METEORS BY MOONLIGHT
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 Saturday, 18th November. For European observers, the shower is expected to peak at 3:44 a.m., with a rate of possibly greater than 100 shooting stars per hour for up to an hour or two either side of this time.
Dust grains given off by comet Tempel-Tuttle as it orbits the Sun once every 33 years produce these meteors. The 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 45 miles per second. 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 appear 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 well above the south-eastern horizon during the expected peak of the shower. However, the last quarter Moon will be very close to the radiant and may wash out some of the fainter meteors.
Those who wish to observe these meteors are advised to find a clear, dark site, and wrap up in plenty of layers of warm clothing. This year it is advisable to look away from the radiant to avoid the bright Moon, or else stand in the Moon's shadow, as the meteors can be seen in any part of the sky.
More information may be found at the Armagh Observatory web site Leonid Pages.
See also: Leonid trail images for 2000.
FOR FURTHER INFORMATION CONTACT: John McFarland at the Armagh Observatory. Tel.: 028-3752-2928.
| Last Revised: 13th November 2000 WWW contact: webmaster@star.arm.ac.uk |
Go to HOME Page  |