A meteor shower is a celestial event in which a number of meteors appear in the night sky. It is usually caused by the Earth passing through the debris left behind by a comet or asteroid. To observe a meteor shower, one can use a TELESCOPE, a device that magnifies distant objects, or visit a PLANETARIUM, an observatory that projects images of stars and planets onto a dome-shaped ceiling. The Leonid meteor shower is one of the most famous meteor showers, occurring every November.