What is the dense sphere of solid iron and nickel at the center of Earth called?

What is the dense sphere of solid iron and nickel at the center of Earth called?

• A. Inner Core
• B. Mantle
• C. Outer Core
• D. Crust

Answer: (A)

At Earth's center sits a dense solid sphere made mostly of iron and nickel. This inner core stays solid because the pressures there are enormous, keeping the metal in a crystalline state despite the very high temperatures. Surrounding it is the outer core, a liquid layer of iron-nickel that flows and drives the planet’s magnetic field. Above that lies the mantle and the crust, which are rocky and less dense. Seismic waves reveal this arrangement: S-waves don’t pass through liquids, which helps identify the liquid outer core, while changes in wave behavior mark the boundary with the solid inner core. The inner core’s radius is about 1,220 kilometers, making it the planet’s central, densest part.

At Earth's center sits a dense solid sphere made mostly of iron and nickel. This inner core stays solid because the pressures there are enormous, keeping the metal in a crystalline state despite the very high temperatures. Surrounding it is the outer core, a liquid layer of iron-nickel that flows and drives the planet’s magnetic field. Above that lies the mantle and the crust, which are rocky and less dense. Seismic waves reveal this arrangement: S-waves don’t pass through liquids, which helps identify the liquid outer core, while changes in wave behavior mark the boundary with the solid inner core. The inner core’s radius is about 1,220 kilometers, making it the planet’s central, densest part.