The Yukon meteorites are thought to be fragments of a C-type asteroid. In addition, carbonaceous chondrites contain mineral grains even older than the solar system - pieces of dust that formed long ago around far distant stars. When comets approach the sun, they begin to warm and melt. Evaporating gases and dust that sputter off the surface of a comet create long tails that can sometimes be seen from Earth. Comet dust forms a cloud of debris that trails the comet in its orbit around the sun.
Comets are about the same size as the smaller asteroids.
Most fireballs are caused by millimeter-sized pebbles. That's about 600 million times brighter than an object with visual magnitude -3. The Leonid meteor shower in November of each year is a well-known event.