Theoretical planetology, also known as theoretical planetary science is a branch of planetary sciences that developed in the 20th century.
Theoretical planetologists, also known as theoretical planetary scientists, use modelling techniques to develop an understanding of the internal structure of planets by making assumptions about their chemical composition and the state of their materials, then calculating the radial distribution of various properties such as temperature, pressure, or density of material across the planet's internals.
Theoretical planetologists also use numerical models to understand how the Solar System planets were formed and develop in the future, their thermal evolution, their tectonics, how magnetic fields are formed in planetary interiors, how convection processes work in the cores and mantles of terrestrial planets and in the interiors of gas giants, how their lithospheres deform, the orbital dynamics of planetary satellites, how dust and ice are transported on the surface of some planets (such as Mars), and how the atmospheric circulation takes place over a planet.
Theoretical planetologists may use laboratory experiments to understand various phenomena analogous to planetary processes, such as convection in rotating fluids.
Theoretical planetologists make extensive use of basic physics, particularly fluid dynamics and condensed matter physics, and much of their work involves interpretation of data returned by space missions, although they rarely get actively involved in them.
Typically a theoretical planetologist will have to have had higher education in physics and theoretical physics, at PhD doctorate level.
Because of the use of scientific visualisation animation, theoretical planetology has a relationship with computer graphics. Example movies exhibiting this relation are the 4-minute "The Origin of the Moon"
One of the major successes of theoretical planetology is the prediction and subsequent confirmation of volcanism on Io.
The prediction was made by Stanton J. Peale who wrote a scientific paper claiming that Io must be volcanically active that was published one week before Voyager 1 encountered Jupiter. When Voyager 1 photographed Io in 1979, his theory was confirmed. Later photographs of Io by the Hubble Space Telescope and from the ground also showed volcanoes on Io's surface, and they were extensively studied and photographed by the Galileo orbiter of Jupiter from 1995-2003.
D. C. Tozer of University of Newcastle upon Tyne, writing in 1974, expressed the opinion that "it could and will be said that theoretical planetary science is a waste of time" until problems related to "sampling and scaling" are resolved, even though these problems cannot be solved by simply collecting further laboratory data.
Researchers working on theoretical planetology include:David J. Stevenson
Jonathan Lunine (University of Arizona professor of theoretical planetology and physics, and Cassini mission scientist specialising on Titan)