EVOLUTIONARY RELATION BETWEEN METEORITES, METEOROIDS AND ASTEROIDS OR COMETS

In this paper,the evolutionary relation between meteorites,meteonoids and asteroids or comets is discussed in our viewpoint on the origin of asteroids and comets.Both asteroids and comets are the'halffinished product' of the planets evolved from the primitive nebula,i.e.surviving planetesimals.They show differences in their evolutions,in their orbital characters and their physics-chemical properties only because they form in different places,under different environmental conditions.When volatile-rich comets moved into inner portion of the solar system,they could easily disintegrate into a great number of meteoroids.The surviving planetesimals in the asteroid region could be broken into fragments by collision.Those fragments and crumbs could turn into smaller asteroids or meteoroids.In fact,there is no strict limits between smaller asteroids and bigger meteoroids.Some fragments of planetesimals in the asteroid region would evolve into meteoroids and enter into the atmosphere of the earth,they could then ablaze out as meteors.Cosmic dust,which failed into the solar system from interstellar space,could also become meteoroids