The smallest planet in the solar system, Mercury is rocky and cratered with almost no atmosphere to serve as protection from meteors. As a result, many impact craters are visible on the surface. The most notable feature on Mercury is the Caloris Basin (also called Caloris Planitia), an impact crater with a diameter of over 950 miles. To better understand Mercury, NASA launched MESSENGER, the Mercury Surface, Space Environment, Geochemistry, and Ranging spacecraft. Since it's launch in 2004, MESSENGER has been orbiting Mercury and has collected over 170,000 images of the planet.
This color enhanced view of Mercury builds upon the monochrome images of Mercury that have been created using MESSENGER imagery. You can see a monochrome version from MESSENGER here. While the monochrome view provides a view similar to what the human eye would see, this new colorful view of Mercury highlights the chemical, mineralogical, and physical differences between the rocks that make up Mercury's surface. Young crater rays, extending radially from fresh impact craters, appear light blue or white. Medium- and dark-blue areas are a geologic unit of Mercury's crust known as the "low-reflectance material", thought to be rich in a dark, opaque mineral. Tan areas are plains formed by eruption of highly fluid lavas. The giant Caloris basin is the large circular tan feature located in the northern hemisphere.