Perseids

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The Perseids Are Falling!
In 2004, search the skies July 23–August 22 for the Perseid meteor showers. http://www.infoplease.com/spot/meteor1.html

A meteor shower is an increase in the number of meteors observed in a particular part of the sky. Meteor showers usually occur annually and with varying intensity.

The meteors of a meteor shower all appear to originate at a single point in the sky known as the radiant point, or radiant. A shower is named for the constellation in which its radiant is located, e.g., the Lyrids appear to come from a point in Lyra, the Perseids from Perseus, and the Orionids from Orion.

On an Average Day . . .
While the average counting rate of meteors for the entire sky is between 5 and 10 per hr, an observer may see twice this number in one part of the sky during a shower, and in the case of the Perseids, possibly more than 100 in an hour. Meteor showers are closely associated with comets.

When a comet breaks up, a swarm of particles eventually becomes scattered out over its entire orbit. If this orbit intersects that of the earth, a meteor shower will be observed. The shower will be particularly intense in those years when the original comet would have been observed.

Significant showers
The Andromedids are associated with Biela's comet, and the Aquarids and Orionids are thought to be associated with Halley's comet. Some of the better-known meteor showers and their approximate dates are: Lyrids, Apr. 22 (2005); Perseids, Aug. 12; Orionids, Oct. 21; Taurids, Nov. 5; Leonids, Nov. 17; Geminids, Dec. 14.

Source: The Columbia Encyclopedia, Fifth Edition Copyright 1993, Columbia University Press. Licensed from Inso Corporation. All rights reserved.