What is a Meteorite ?
A meteorite is a solid piece of material which reaches the surface of the Earth after passage through the atmosphere.
Meteorites are not to be confused with meteoroids or meteors. To go over it briefly, a meteor is the visual effect you see, caused by the passage of meteoroid through the atmosphere. The small which enters the atmosphere and causes the 'meteor' effect is called a 'meteoroid'. A meteoroid can only become a 'meteorite' if it reaches the surface of the ground.
The majority of the bodies producing the meteors we see are cometry in origin. They are small grains of dust or particles the size of a grain of sand and are unable to survive the passage through the atmosphere intact. Most of the larger bodies which survive the plunge through the atmosphere and to the surface are asteroidal in origin. Scientists have been able to find this out by deducing orbits for the larger bodies which have been observed in the air and recovered. The orbits can be found for fireballs or bolides which produce meteorites by using double station plotting and more accurately double station photography. The fireball is captured on two or more cameras separated by many kilometres and using trigonometry and the difference in position of the fireball against the background stars its orbit can be recovered.
The fact that it is known many meteorites come from asteroids gives scientists the opportunity to study the early solar system using unaltered meteorite material.