Probing the Interiors of Planets with Geophysical Tools

Abstract

Understanding the structure and processes of the deep interior of the planets is crucial for understanding their origin and evolution. As deep planetary interiors are inaccessible to direct observation, the most effective way to explore them is through geophysics, which provides tools for “remote sensing” of the interior. The four major classes of geophysical techniques that are used to probe planetary interiors are seismology, geodesy (which includes both gravimetry and planetary dynamics), heat flow, and electromagnetism. Seismology is the most powerful tool available for probing the interior of planets, and can provide detailed information on interior boundaries and clues about composition. Observations of gravity and rotation provide information on the distribution of mass within a planet due to overall structure (crust, mantle, core). Heat flow measurement provides information about the subsurface temperature structure and the energy driving interior processes. Electromagnetic techniques are primarily sensitive to temperature and the presence or absence of fluids or metallic phases.