It is estimated that anywhere from 37,000 to 78,000 tons of meteorites hit Earth’s surface each year. Most of this figure is made up of micrometeorites, which are dust-sized specks about 50 µm (micrometer - one millionth of a meter) to 2 mm in diameter. Approximately one micrometeorite lands on every square meter of Earth per year. It is most likely that loads of micrometeorites are right outside your door!