Geology of solar terrestrial planets

Part of a series on
Geology
Science of the solid Earth
Index Outline Category Glossary History (Timeline)
Key components Minerals Rock (Igneous Sedimentary Metamorphic) Sediment Plate tectonics Strata Weathering Erosion Geologic time scale
Laws, principles, theories Stratigraphic principles Principle of original horizontality Law of superposition Principle of lateral continuity Principle of cross-cutting relationships Principle of faunal succession Principle of inclusions and components Walther's law
Topics Composition Geochemistry Mineralogy Sedimentology Petrology Structure of Earth Landform structures Geomorphology Glaciology Structural Geology Volcanology Geologic history Geological history of Earth
Research Branches of geology Geologist (List) Methods Geological survey
Applications Engineering Mining Forensics Military
Planetary geology Lists of geological features of the Solar System Geology of solar terrestrial planets By planet and body Mercury Venus Moon Mars Vesta Ceres Io Titan Triton Pluto Charon
Geology portal
v t e

The geology of solar terrestrial planets mainly deals with the geological aspects of the four terrestrial planets of the Solar System – Mercury, Venus, Earth, and Mars – and one terrestrial dwarf planet: Ceres. Earth is the only terrestrial planet known to have an active hydrosphere.

Terrestrial planets are substantially different from the giant planets, which might not have solid surfaces and are composed mostly of some combination of hydrogen, helium, and water existing in various physical states. Terrestrial planets have a compact, rocky surfaces, and Venus, Earth, and Mars each also has an atmosphere. Their size, radius, and density are all similar.

Terrestrial planets have numerous similarities to dwarf planets (objects like Pluto), which also have a solid surface, but are primarily composed of icy materials. During the formation of the Solar System, there were probably many more (planetesimals), but they have all merged with or been destroyed by the four remaining worlds in the solar nebula.

The terrestrial planets all have roughly the same structure: a central metallic core, mostly iron, with a surrounding silicate mantle. The Moon is similar, but lacks a substantial iron core.^[1] Three of the four solar terrestrial planets (Venus, Earth, and Mars) have substantial atmospheres; all have impact craters and tectonic surface features such as rift valleys and volcanoes.

The term inner planet should not be confused with inferior planet, which refers to any planet that is closer to the Sun than the observer's planet is, but usually refers to Mercury and Venus.