Another Red Planet: Pluto

With New Horizons set to make the long-awaited July 14th fly by of Pluto, we are getting an unprecedented view of this distant dwarf planet.   And now we can clearly see we have one more red planet (see the NASA image above), the color attributed to hydrocarbon molecules formed from the interaction of cosmic rays and solar ultraviolet light with Pluto's methane atmosphere and surface.

New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado, recently stated:

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.

While Dr. Stern may believe everyone knew Pluto was a red planet, I am not sure that was the case with everyone in the past.  Take a look at solar system illustration below and you will see it was not a red planet for everyone.  Yet now we know, and I expect future graphics will be somewhat different.