ON THE ORIGIN OF COMETS

Comets are rich in volatile material.It suggests that comets should form and keep for a long time in the low temperature region of the outer solar system.This paper analyses the structure of the outer edge region of the solar nebular disk,and shows that no formation zone of comets can exist there.We consider that comets would evolve from the surviving planetesimals in Jupiter-Neptune region.Such planetesimals make of both the rocky and icy materials and may be called as eometesimals.