What term is used to describe the dense sphere of solid iron and nickel at the center of the Earth?

The dense sphere of solid iron and nickel at the center of the Earth is referred to as the inner core. This region, which is primarily composed of these heavy metals, is under immense pressure due to the weight of the overlying materials. The high pressures contribute to the solid state of the inner core, despite the extremely high temperatures that can exceed those found on the surface of the sun.

The inner core is surrounded by the outer core, which is in a liquid state and made up of the same materials but behaves differently due to lower pressure. The crust is the thin outer layer of the Earth where we live, and it consists primarily of lighter materials like silicates. The asthenosphere is part of the upper mantle and is characterized by its semi-fluid properties, allowing tectonic plates to move. Each of these layers plays a distinct role in the structure and functioning of the planet, but the inner core is specifically identified as the solid, dense sphere located at the very center.