Mars

Photo: NASA, Jet Propulsion Laboratory, and University of Arizona
NYTimes:
Mars is not really blue. But if they looked at realistically colored images, scientists would be trying to distinguish between red rocks and soil and not-quite-so-red rocks and soil. The false-color images, like this one of Ius Chasma in the western part of the Valles Marineris canyon system, stretch the color palate to accentuate details.