Meteoroids are small rocky or metallic bodies that orbit the sun, ranging in size from grains to objects up to a meter wide. They are distinguished as objects significantly smaller than asteroids. Objects smaller than meteoroids are classified as micrometeoroids and interplanetary dust. Most meteoroids come from the asteroid belt, having been perturbed by the gravitational influences of planets, but others are particles from comets, giving rise to meteor showers. Some meteoroids are fragments from bodies such as Mars or the Moon, that have been thrown into space by an impact.

When meteoroids intersect with Earths atmosphere at night, they are likely to become visible as meteors. If meteoroids survive the entry through the atmosphere and reach Earths surface, they are called meteorites. Meteorites are transformed in structure and chemistry by the heat of entry and force of impact.

In summary, meteoroids are small rocky or metallic bodies that orbit the sun, and when they enter Earths atmosphere, they can become visible as meteors. If they survive the entry and reach Earths surface, they are called meteorites.