These two views of Mars are derived from the MGS Thermal Emission
Spectrometer (TES) measurements of global broadband (0.3 - ~3.0 microns)
visible and near-infrared reflectance, also known as albedo. The range
of colors are in dimensionless units. The values are the ratio of the amount
of electromagnetic energy reflected by the surface to the amount of
energy incident upon it from the sun (larger values are brighter surfaces).
The TES instrument was built by Santa Barbara Remote Sensing and
is operated by Philip R. Christensen, of Arizona State University, Tempe, AZ.