The material in the outer core is a fluid. A fluid is any material that can flow, such as a liquid or gas. Within a fluid, differences in density can cause motion. The parts of the fluid that are denser sink to the bottom. The parts of the fluid that are less dense float to the top. Thus, differences in density cause convection in water being heated on a stove,
Answer: The outer core, about 2,200 kilometers (1,367 miles) thick, is mostly composed of liquid iron and nickel. The NiFe alloy of the outer core is very hot, between 4,500° and 5,500° Celsius (8,132° and 9,932° Fahrenheit).
