Astrogeology, the science that applies the principles of geology to the study of solid bodies of the solar system other than the earth. Using the techniques of geophysics, geochemistry, and other fields of geology, scientists can learn about the composition, structure, and development of such bodies as the moon and the various planets and their satellites. Scientific data and photographs transmitted to earth by space probes are important sources of information in astrogeology. Another valuable source of information is the direct analysis of meteorites and of rock samples from the moon.