What are Asteroids?
Asteroids | Objects That Orbit the Sun
Asteroids are rocky and metallic objects that orbit the sun. They can be as small as a pebble or as large as 1000km in diameter. They're believed to be the leftovers from the formation of the solar system although some believe they may be the remains of a planet that was destroyed in a massive collision many millions of years ago.
When an asteroid is on a collision course with Earth it's called a meteoroid and should one enter our atmosphere, friction causes it to incinerate into a streak of light which is known as a meteor. If the meteoroid does not burn up completely the part that's left which subsequently crashes into the surface of Earth is called a meteorite.