A meteor that has fallen to the ground is called a meteorite. Meteorites can be found in most parts of the world, and are generally composed of stone, iron, or a combination of the two. Several times during the year, hundreds of meteors can be seen in a single night. This event is known as a meteor shower and happens when the Earth passes through the debris left behind by a comet . Most of this debris is the size of dust or sand.
Some particles can be a little larger, about the size of a small pebble.
These larger particles can cause extremely bright meteors known as fireballs . The Doomsday Legacy The Earth-crossing asteroids present some reason for concern. Several hundred of these have been discovered with a diameter of over a mile. At the extremely high speed with which these objects travel, even small asteroids can cause a great deal of damage. Barringer Crater in Arizona is nearly a mile across and was formed by a meteor only 150 feet in diameter.