In this interesting VIS image, taken by the NASA - Mars Odyssey Orbiter on March, 9th, 2004, and during its 9.917th orbit around the Red Planet, we can see a little bit of the large and dark-colored (---> made out of Basalt, maybe?) Dunefield that is found of the Floor of Keeler Crater, an ancient Impact Crater located in the Martian Region known as Terra Sirenum.
Keeler Crater, as we have already written before, is an Impact Crater that, to be more specific, is found in the Phaethontis Quadrangle of Mars, and centered at 61° South Latitude and 151,3° West Longitude. It is approx. 95 Km (such as about 58,995 miles) in diameter and it was so named after James Edward Keeler (an American Astronomer who was born on September, 10, 1857, in La Salle - Illinois - and died in San Francisco, California, on August, 12, 1900), and the name was approved by the International Astronomical Union (or "IAU", for short) in the AD 1973.
Just out of curiosity, Keeler Crater lays to the North of Trumpler Crater (another, and more recent, Impact Crater that "interacts" with Keeler Crater). Why such an "interaction"? Nobody can say for sure but, most likely, after Keeler was formed, a later - and powerful - impact, formed Trumpler Crater and, in the process, destroyed part of Keeler Crater itself.
This frame seems to have been taken with the Camera onboard the NASA - Mars Odyssey Orbiter a little bit out of focus, but the reason of such an effect can be found in the presence of a (relatively) layer of Fog and suspended Dust Particles hovering in the lower Atmosphere above the Crater.
Latitude (centered): 60,2955° South
Longitude (centered): 208,2030° East
This image (which is an Original Mars Odyssey Orbiter falsely colored and Map-Projected frame published on the NASA - Planetary Photojournal with the ID n. PIA 19751) has been additionally processed, magnified to aid the visibility of the details, contrast enhanced and sharpened, Gamma corrected and then re-colorized in Absolute Natural Colors (such as the colors that a normal human eye would actually perceive if someone were onboard the NASA - Mars Odyssey Orbiter and then looked down, towards the Surface of Mars), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.