These images were obtained by the Dawn spacecraft on July 23, 2011. The bottom two images are false-color, where different colors represent visible and infrared light wavelengths. Scientists are studying these images to better understand the different materials on the surface. The Visible and Infrared Mapping Spectrometer is an imaging spectrometer, provided by the Italian Space Agency and Istituto Nazionale di Astrofisica, capable of delivering detailed images in 864 spectral bands.
Blue represents wavelengths of 438 to 653 nanometers, red represents wavelengths of 438 to 750 nanometers, and green represents wavelengths of 653 to 917 nanometers.
The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington. UCLA is responsible for overall Dawn mission science. The visible and infrared mapping spectrometer was provided by the Italian Space Agency and is managed by the Italy's National Institute for Astrophysics, Rome, in collaboration with Selex Galileo, where it was built.
More information about the Dawn mission is online at http://www.nasa.gov/dawn and http://dawn.jpl.nasa.gov.