A terrestrial planet is a celestial body distinguished by a predominantly rocky or metallic composition, unlike gas giants which are composed primarily of volatile compounds. Structurally, these planets typically consist of an inner core, often composed of dense metals, surrounded by a mantle of silicates, which in turn is covered by a crust. Their geological features frequently include impact craters, mountain ranges, and evidence of past volcanism, making them candidates for studying planetary formation models and the processes of geochemical differentiation. The internal dynamics of these bodies, driven by residual heat and tidal forces, are central to their geophysical study.