Leonid Meteors Outburst

This year's annual display of the Leonid meteor shower occurs from 10th to 21st November, with the broad peak of activity occurring during the night of Tuesday 17th and Wednesday 18th. According to theoretical predictions by David Asher of the Armagh Observatory, and colleagues, there may be up to 100 meteors per hour seen under ideal conditions during the late evening of the 17th and early morning of the 18th November.

Meteors, or shooting stars, are the streaks of light produced when small, cometary dust particles, orbiting the Sun, run into the Earth's atmosphere and vaporise in a few seconds at altitudes of about 100 km. Large particles, up to pebble-size, can produce very bright meteors known as fireballs, rivalling in luminosity some of the brighter planets. The Leonid meteors are produced by particles that are shed from periodic comet 55P/Tempel-Tuttle every time it passes close to the Sun during its approximately 33-year orbital journey. The radiant of the Leonids, that is, the area from which they appear to diverge, lies in the 'head' of the constellation Leo.

This year's activity results mainly from the Earth passing through trails of dust emitted by Comet Tempel-Tuttle in the years 1466 and 1533. Esko Lyytinen and Markku Nissinen of Finland further predict that the 1466 trail may produce enhanced rates generally, with at least 40 meteors per hour occurring for much of November 17th.

Leonids travel at very high speeds through our atmosphere, at up to about 160,000 miles per hour, and many leave lasting glows known as persistent trains. World-wide, conditions this year are favourable for observing the shower as there will be no interference from the nearly new Moon. The most favoured longitudes are from the extreme east of Europe to Japan. It is likely that viewers in the UK and Ireland will miss the main activity but might catch some long Earth-grazing meteors at the end of the display at around midnight on 17/18th November, after the radiant rises in the north-east at about 10:30pm. However, observers should, as usual, be on the alert for any unexpected meteor activity.

Weather permitting, observers should make themselves comfortable in a dark site away from artificial lights, and scan the area of sky from the north-west to east. At this time of year, you should of course wrap-up well in several layers of warm clothing to ward off the cold. Results from around the world will be posted at this web site.

See also: Leonids 2009

FOR FURTHER INFORMATION PLEASE CONTACT: John McFarland at the Armagh Observatory, College Hill, Armagh, BT61 9DG. Tel.: 028-3752-2928; FAX: 028-3752-7174; jmfat signarm.ac.uk.

Last Revised: 2009 November 10th