Inner Planets
Mercury, Venus, Earth, and Mars
Outer Planets
Jupiter, Saturn, Uranus, Neptune (Pluto)
Asteroid Belt
Most of the asteroids are between the orbits of Mars and Jupiter. This separates the inner planets from the outer planets.
Perturbations In the Orbit
Perturbations in the orbit of an asteroid can cause it to become a meteor.
Comet
A comet is made up of a nucleus, a coma, and a tail