* Iron (Fe): This is the dominant element, making up around 88% of the inner core.

* Nickel (Ni): This is the second most abundant element, making up around 5.5%.

* Other elements: Small amounts of other elements are also present, including sulfur (S), silicon (Si), and oxygen (O).

It's important to note that the inner core is a solid ball of iron and nickel, even though the temperature is extremely high (around 5,200 °C / 9,392 °F). The immense pressure at the center of the Earth, exceeding 3.5 million times atmospheric pressure, is what keeps the inner core solid.

The extreme pressure and temperature make it impossible to directly sample the inner core. We infer its composition and properties through:

* Seismic waves: Studying how seismic waves from earthquakes travel through the Earth provides information about the inner core's density, composition, and state.

* Earth's magnetic field: The Earth's magnetic field is thought to be generated by the movement of molten iron in the outer core, which is influenced by the solid inner core.

* Meteorites: Some meteorites are thought to have originated from the early Earth's core, providing clues about its composition.