We know that there are billions of meteors in the universe. These exist after star collisions which break into smaller pieces.
When these meteorites enter the Earth’s atmosphere, 100 kilometers above its surface, at a speed of between 50 and 70 kilometers per second, they begin to decompose and turn into dust, since the temperatures that develop are huge. This powder becomes a shiny substance at such temperatures and sometimes evaporates.
[Source: http://www.phys.org]
