|The study of Earth and planetary sciences encompasses a broad exploration and understanding of the origin and evolution of the Earth, its sister planets and satellites, and life forms found on and in Earth’s crust. Earth science has been unified by the theory of plate tectonics, which considers Earth’s surface to be broken into a number of interlocking plates. Plate movements result in ocean basin formation, mountain building, and plate translation along great faults such as the San Andreas, only 15 kilometers east of Santa Cruz. Most earthquakes and volcanic activity occur at modern plate boundaries. Energy, mineral, and water resources, geologic hazards, climate change, and earthquake hazard reduction comprise some pressing societal concerns of the Earth sciences. A large question in planetary sciences is whether Earth-like tectonics operate on other planets and satellites, and, if not, how their interiors and surfaces have evolved.