The three primary types of asteroids are C-type, M-type and S-type. Asteroids are categorized according to their composition. C-type asteroids are carbonaceous, M-type asteroids are metallic and S-type asteroids are silicaceous.
Three-fourths of the asteroids in the solar system's asteroid belt are carbonaceous. Dark C-type asteroids are found in the portion of the asteroid belt facing away from the sun. M-type asteroids are found in the middle of the belt, and most of the metal in M-type asteroids is iron and nickel. The S-type asteroids reside in the inner portion of the asteroid belt.
The asteroid belt is located between Mars and Jupiter. Most of the asteroids in our solar system are found in this belt, though asteroids can be located throughout space. Asteroids are thought to be leftover material from the formation of the solar system, but they're not close enough together to form planets. Asteroids in the belt range in size from 20 feet to 583 miles across. Most are irregularly shaped and are pitted and cratered.
Asteroids occasionally enter Earth's atmosphere. When an asteroid crashes to Earth it is called a meteorite. Small meteorites do little damage. Large ones entering the atmosphere create shock waves and other potentially hazardous conditions and are thought to be behind some extinction events.