A meteor is a bright streak of light that appears in the sky and is often called a shooting or falling star because it looks like it is falling from the sky. The brightest meteors are often called fireballs. When a chuck of matter, called a meteoroid, from outer space enters the atmosphere around the earth, the friction caused by the entry causes the air around it to glow. This lights up the trail of gases from the meteor and is why we can see the light with the naked eye. Most meteors burn out before they reach the Earth’s atmosphere. The ones we see in the night sky only glow for a second or two.
There are millions of meteors entering the atmosphere every day and night. We cannot see them during the day because of the daylight. They come from meteoroids and most are only about the size of a pebble. They become visible at altitudes of 40-75 miles above the surface of the Earth, but they disintegrate by the time they come within 30-60 miles of the Earth. However, some meteors do reach the Earth’s surface, in which case they are called meteorites.
Meteoroids, like the planets, revolve around the sun. Some of them travel faster than others and it is these that glow when they enter our atmosphere because they are traveling faster than the Earth and they clash with the lower speed.
There are three kinds of meteorites that have landed on Earth – stony, iron and stony-iron. The stony meteorites contain combinations of different minerals, such as iron, silicon, oxygen and magnesium. Some are made from the materials of planets, while others are parts that have broken off from asteroids.
When meteorites reach the earth they are usually very tiny. Some large ones have done so, though, such as a 66 pound meteorite that landed on a farm in Nambia. Antarctica seems to have numerous meteorites on its surface, which scientists have studied extensively to help them gain ground in the quest for knowledge of space. When these large meteorites crash to earth the impact causes a crater. There are over a hundred such impact craters or basins on Earth, the largest being the Meteor Crater in Arizona, which measures over four thousand feet wide and is about 500 feet deep.
Meteor showers occur when the Earth meets up with many meteors at the same time. This can occur several times a year and produce a night sky that seems to light up with tiny sparks. The Leonid shower, for example, occurs each year in November.