They range in size from several miles to the size of a small pebble. Sometimes these objects get close enough to the Earth that they are pulled in by its gravity . Outside the Earth's atmosphere , these objects are known as meteroids. They can enter the atmosphere at speeds of up to 45,000 miles per hour. Once a meteroid enters the atmosphere, it is known as a meteor.
Most meteors burn up in the atmosphere before they can reach the ground.
The bright, glowing streak they leave in the sky is cause by hot ionized gases formed from the heat of friction. Occasionally, a large meteor will survive its trip through the atmosphere to reach the ground. 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.