It is believed that comets come from the Oort Cloud or the Kuiper Belt. The Oort Cloud is located on the outer portion
of the solar system and the Kuiper Beltis just beyond Neptune. The best description for a comet is a dirty snowball. The
size of comets can range from 8 to 16 km across. Comets are made-up of a combination of water ice and dust. Comets can also
contain frozen carbon dioxide, carbon monoxide and methane. The four main parts of a comet are nucleus, coma, hydrogen corona
and the tails. The nucleus of a comet, which mainly consists of water ice and dust, is responsible for the spectacular show
a comet puts on. The nucleus reacts with the Suns heat and causes the gases of the comet to sublimate. The coma is created
by these escaping gases and dust. The coma can extend over a million km from the nucleus. A comet normally only has a dust
and an ion tail. The dust tail is the prominent part of the comet and can reach lengths of 10 million km. As the name implies,
the dust tail is comprised of dust blown off from the escaping gas. The ion tail can be 10 times the size the dust tail.
This tail is composed of plasma and reacts to the Suns heat by producing ions. This tail appears bluish in color. A third
tail, made up mainly of sodium, was discovered in the Comet Hale-Bopp. This tail appears yellow in color. The hydrogen corona
is the largest aspect of the comet and can extend many million km from the comet.