Some components, like sodium, are easy to identify but others are difficult, because they are dim or masked by other radiations. Curved tails in comets have the same light characteristics as the Sun, and therefore are reflecting sunlight. Because in space only solid particles reflect sunlight, these curved tails are primarily dust. Also detected are water, carbon dioxide, and many combinations of hydrogen, carbon, oxygen, and nitrogen. Probably, some substances in the nucleus, such as water and carbon dioxide, have broken apart and recombined to give many other compounds.
Comets contain methane and ethane.
On Earth, bacteria produce almost all methane, and ethane comes from methane. 33 Dust particles in comets vary in size from pebbles to specks smaller than the eye can detect. How dust could ever form in space is a recognized mystery. In fact, the particular type of olivine, which is rich in magnesium, is especially abundant in rocks beneath oceans and continental crust. Crystalline patterns form because atoms like to arrange themselves in patterns that minimize their total energy.