Comets are close to the sun. The surface of the comet warms and gasses boil off carrying dust. The coma is made of gas and dust.It is sometimes called a dirty snowball. A comet loses material during each trip around the sun. When all gases boil off, solid material becomes either a meteoroid or asteroid. There are three parts of a comet: nucleus,coma,and tail. The tail is always facing away from the sun.