Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto  Such ices have a tendency to vaporize, producing an atmosphere
Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes, astronomers have concluded that the components of Pluto' s atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance
A mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed.