More at the THEMIS Instrument site
Primordial and prehistoric come together in a lasting bond of something old, something new, something orange, and something blue. In this false-color image, blue signals cooler sand or dust around an ancient crater, which dates back to a violent time of cataclysmic collisions about 4 billion years ago, shortly after Mars formed. Later, sheets of lava streamed across the surface and lapped against the crater walls. These younger lava rocks "glow" orange and yellow since they retain more heat at night than the sand and dust.
September 19, 2007