Perseid Meteors in 2013

Perseid Meteor from 2005

This yearòÀÙs Perseid meteor shower is already in progress and will continue till around 24th August. The peak of activity is expected to occur on the evening of 12th August with a maximum of around 50 òÀÓ 100 meteors per hour under ideal conditions. However, a single observer may only see a fraction of this number, depending on the clarity of the sky and the fraction of the sky unclouded. Most people observing from a dark, clear observing site should expect to see around a dozen meteors per hour.

The Perseid meteors take their name from that of the constellation, Perseus, from where they appear to radiate. They are usually one of the most reliable annual meteor displays. The meteors are generally fast and bright, and may leave glowing 'persistent trains'. Assuming a clear sky, conditions for observing the peak are good this year, with a waxing crescent Moon on the night of August 12th.

Most meteors are produced by comets, which shed trails of dust while passing through the inner solar system on their elliptical orbits around the Sun, In this case, the comet is a Halley-type short-period comet, 109P/Swift-Tuttle which was discovered in July 1862 and has an orbital period of 133 years.

In the case of the Perseids, the Earth encounters this dust at high speed òÀÔ over 200,000 kilometres per hour òÀÔ and this causes the small dust grains, with sizes ranging from typically a few millimetres up to a centimetre or more, to vaporize in the EarthòÀÙs atmosphere at a height of almost 100 kilometres. It is this vaporization, or burning up of the dust in the EarthòÀÙs atmosphere, that produces the visible meteor.

During the late evening of 12th August, the constellation Perseus will lie low in the north. In order to see the Perseids to best effect (although it is possible to see some meteors while looking in any direction) you should select, if possible, a dark, clear site with a good vista towards the north or east. To observe meteors to best effect, you should always avoid light pollution, and allow time for your eyes to become accustomed to the dark. Then, look at an angle of about 45 degrees away from the radiant, in this case the rising constellation of Perseus, keeping the radiant near the edge of your field of view. To avoid fatigue, wrap up warm and recline in a comfortable chair under a rug or sleeping bag, if cold.

During the 1990s, when the PerseidsòÀÙ parent periodic comet 109P/Swift-Tuttle last passed through the inner planetary system, there was much shower activity. Although the comet is now receding from the inner solar system, and will not return until around 2126, the number of meteors has remained at a fairly high level. Look out for the planets Venus, low in the west after sunset, and Saturn, near the Moon on the 12th. For general observations of meteors, check Armagh ObservatoryòÀÙs web page Meteor Camera Detections.

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

Last Revised: 2013 August 2nd