Entry into Earth's atmosphere of multiple meteoroids (see meteor ), traveling in parallel paths, usually spread over several hours or days.
Most meteor showers come from matter released during passage of a comet close to the Sun, and they recur annually as Earth crosses the comet's orbital path. Meteor showers are usually named for a constellation (e.g., Leonid for Leo) or star in their direction of origin. Most showers are visible as a few dozen meteors per hour, but occasionally Earth crosses an especially dense concentration of meteoroids, as in the great Leonid meteor shower of 1833, in which hundreds of thousands of meteors were seen in one night all over North America.