| General composition | Metallic |
|---|---|
| Outer part | Liquid |
| Inner part | Solid |
Definition and context
The core forms the planet’s central region and differs from the mantle in composition and properties. The basic description distinguishes a liquid outer core and a solid inner core. This structure is inferred from various observations, including the behavior of seismic waves.
It is not a direct observation made by drilling. Models must explain arrival times, paths, and other evidence in a compatible way. When studying a drawing, it is useful to distinguish the well-established general structure from details that are still being investigated. This fact sheet does not aim to resolve debates about deep dynamics: it presents the basic framework and emphasizes that an indirect inference can be strongly constrained by measurements.
What we know and its limits
Introductory reference sheet. Properties and applications depend on measurement conditions; consult the sources before making comparisons.
Follow the evidence
The original sources for exploring this explanation and its limits.
- The Interior of the Earth
U.S. Geological Survey
Seismic and experimental evidence about Earth's layers. - This Dynamic Earth · Inside the Earth
U.S. Geological Survey
Earth's crust, mantle, core, and mechanical structure.
Image credits
SciClue · AI-generated illustration (OpenAI) · Original source · Recurso editorial de SciClue · generado con IA