|a transient rain of meteors, such as the Perseids, occurring at regular intervals and coming from a particular region in the sky. It is caused by the earth passing through a large number of meteoroids (a meteor swarm)|
A brief period of heightened meteor activity, often occurring regularly in a particular part of the sky at a particular time of year. Meteor showers are generally named after the constellation in which they appear to originate; thus the Perseids appear to originate in the constellation Perseus and the Leonids in the constellation Leo. The showers occur when the Earth passes through a region having a greater than usual concentration of interplanetary debris, such as particles left by a disintegrating comet, at certain points in its orbit. Although the meteors enter the Earth's atmosphere on parallel trajectories, perspective makes it appear as if they originate from the same point in the sky, known as the radiant.