Astrogeology, also known as planetary geology, is the study of the geological history and evolution of planets, moons, asteroids, comets and meteorites. It is a relatively young science that only began in the early 19th century with the development of telescopes powerful enough to allow detailed observation of other worlds. Astrogeologists use a variety of techniques to learn about the composition, structure and evolution of these bodies including spectroscopy, seismology and geochemistry.
The first step in any astrogeological analysis is to determine the age and composition of a body. This can be done through a variety of means including studying the light emitted by an object (spectroscopy), measuring its gravity (seismology) or analyzing its chemical makeup (geochemistry). Once this information is known, astronomers can begin to piece together the history of a body by studying its physical features. For example, craters are thought to form from impacts with other objects and can be used to date the surface on which they sit. By studying the distribution and size of craters on different worlds, astronomers can get an idea of how old their surfaces are.
Astrogeologists have made some remarkable discoveries in recent years thanks to advances in technology. In 2015, for example, data from NASA’s New Horizons mission allowed scientists to create a 3D map of Pluto which revealed a surprisingly complex surface featuring mountains up to 11000m tall! And in 2018, data from NASA’s InSight mission showed that Mars has an active interior similar to Earth’s – something that was previously thought impossible. These are just two examples of how astrogeology is helping us to better understand our place in the Universe.