Pluto was once the ninth and the farthest planet in the solar system but due to new discoveries and further analysis of other bodies in the solar system, Pluto was recategorized as one of the dwarf planets together with Eris, Ceres, Makemake and Haumea.
Bright and dark areas:
Our latest telescopes are not powerful enough to go farther to analyze to the full extent the exact composition of Pluto. The map of Pluto’s surface captured by NASA consists of bright and dark areas. Bright areas are said to be Nitrogen ice, with small amounts of frozen methane, ethane and carbon monoxide gases. The Dark areas on the other side are said to be composed of organic material and/or products of photochemical reactions.