A meteor shower, some of which are known as a "meteor storm" or "meteor outburst," is a celestial event where a group of meteors are observed to radiate from one point in the sky. These meteors are small fragments of cosmic debris entering Earth's atmosphere at extremely high speed. They vaporize due to friction with the air, leaving a streak of light that very quickly disappears. Most of the small fragments of cosmic debris are smaller than a grain of sand, so almost all fragments disintegrate and never hit the earth's surface. Fragments which do contact earth's surface are called meteorites.