[1][2] Although the geo- prefix typically indicates topics of or relating to Earth, planetary geology is named as such for historical and convenience reasons; due to the subject matter, it is closely linked with more traditional Earth-based geology.Despite their outermost layers being dominated by gases, the giant planets are also included in the field of planetary geology, especially when it comes to their interiors.Eugene Merle Shoemaker is credited with bringing geologic principles to planetary mapping and creating the branch of planetary science in the early 1960s, the Astrogeology Research Program, within the United States Geological Survey.[citation needed] Simulated interplanetary missions performed on Earth have studied procedures and tools for planetary geology.[11] The standard names are chosen to consciously avoid interpreting the underlying cause of the feature, but rather to describe only its appearance.
Surface of Mars in a false-color photograph by the
Viking 2
lander, December 9, 1977