Pluto is mostly brown. The above picture captures the true colors of Pluto as
well as the highest surface resolution so far recovered. No spacecraft has yet
visited this most distant planet in our Solar System. The above map was created
by tracking brightness changes from Earth of Pluto during times when it was
being partially eclipsed by its moon Charon. The map therefore shows the
hemisphere of Pluto that faces Charon. Pluto's brown color is thought dominated
by frozen methane deposits metamorphosed by faint but energetic sunlight. The
dark band below Pluto's equator is seen to have rather complex coloring,
however, indicating that some unknown mechanisms may have affected Pluto's
surface.
