- Comets are made up of a mixture of dust, ice, rocky material, and organic compounds.
- They have highly elliptical orbits that bring them close to the Sun and then far out into the solar system.
- As a comet approaches the Sun, solar radiation causes its ices to vaporize, creating a glowing coma (the fuzzy atmosphere around the nucleus) and often a tail that points away from the Sun due to the solar wind.
- Comets are often called "dirty snowballs" because of their icy composition.
- Famous comets include Halley's Comet, Hale-Bopp, and Comet Hyakutak