Asteroids and meteors
- An asteroid typically has a nearly circular orbit and is large enough to be observed in a telescope from earth
- Meteoroids are much smaller and are typically only noticed when they enter the earth's atmosphere, becoming meteors.
- Most of these burn up due to air friction, long before reaching the surface
- Some explode in mid-air
- Some actually reach the Earth (meteorites); they make a crater if they hit land.