Comets are the relatively small, icy objects that orbit a star. They are classified as “small solar system bodies”, as are asteroids. Along with ice, they contain rocky dust and other complex chemicals, leading them to be described as “dirty snowballs.” Spectra can be used to determine the composition of comets. From them, we know that comets formed far from the sun because the compounds they have can only have condensed in the outer regions of the solar system. Among them include hydrogen compounds, such as water. Carbon Monoxide and Dioxide formed in only the most distant regions of the solar nebula, and comets contain them as well. Further, comets also contain traces of organic molecules as well. This is significant, because this provides the speculation that comets are responsible for providing the organic material that made life possible.