Pluto is red-brown
New Horizons’ RALPH instrument confirms that Pluto is reddish brown probably caused by hydrocarbon molecules that are formed when cosmic rays and solar ultraviolet light interact with methane in its atmosphere and on its surface.
Pluto’s reddish color has been known for decades, but New Horizons is now allowing us to correlate the color of different places on the surface with their geology and soon, with their compositions. This will make it possible to build sophisticated computer models to understand how Pluto has evolved to its current appearance.