As a comet travels close to the Sun, it warms up and part of the comet evaporates. After a comet has rotated around the Sun many times, a lot of small pieces are left along the way of the comet, that's what we call meteor showers.
A meteor shower happens when the Earth passes through the path of a comet. When this happens the small pieces of the comet, most no larger than a grain of sand, create light signals in the night sky.
Pieces of dust and boulders which enter the Earth's atmosphere are called meteors. On any given night, there are several small meteors that shoot across the sky.
Many of these meteor showers can be predicted and occur at the same time each year.
It happens in the space and the atmosphere of the earth.